1981 Cadillac going in 8-6-4 mode

[@mitch9521]

Probably the last functioning 8-6-4 Cadillac lol

[@punker4Real]

my grandpa's lasted up tell my uncle blew the transmission :( in 2002 he had the VFD cluster that thing was cool.. back in the good old days it was like having a TV in your car

[@muchmore15]

I have one that runs beautifully 😁

[@brianchaplin9085BEC.]

I have an 85 Fleetwood limousine. My main problem is emmisson problems and nothing to do with the downfall of the HT 4100 .

[@thethomasj1795]

@@muchmore15 me too, once I disconnected the system. If that car had a 4 speed w/OD it would have been perfect.

[@forlornhope1116]

@@thethomasj1795 4.8 or 5.3 LS and 8 speed 8l90 from a wrecked later model GM pickup, you won't have to worry about reliability and you'll be shocked what kind of fuel economy you can get from a car with 2.43/2.73 highway gears with an 8 speed. Driveline can be had for under a grand from many salvage yards.

[@plap.]

I'm old enough to remember when they were new. This system was known to suck when they were still in the showroom. The fact it still is there and/or works is amazing

[@kirbywinters1291]

They still suck even in newer cars and trucks that have it

[@leadfoot8593]

Sips fuel and slurps oil! Plus the lifters not pumping back up and so on.

[@johnnymitz]

I'm old enough too. I remember when these came out. They truly never worked as promoted. When the engine went into 6-cyl or 4-cyl mode, they sounded like old John Deere tractors. And it was never seamless when they transferred from one mode to another. So yes, it is amazing that we see one here that still works. Well done.

[@AFellowDoktuh]

@@johnnymitz weren't they also known to shorten the lifespan of the motor?

[@bigman7293]

@@AFellowDoktuh most definitely. Even newer engines that have this do. Newer DOD systems in GM engines still have that issue. I just replaced a DOD 5.3l with 120k miles in a 2013 Sierra because there was metal in the oil and it was clacking/knocking.

[@isaakwelch3451]

I'm glad you saved this car and are preserving its cylinder deactivation

[@kobra6660]

To bad you can't get ahold of one of these engines and bring back to its original 8 6 4

[@isaakwelch3451]

@@kobra6660 they're out there, it certainly could be done

[@kobra6660]

@@isaakwelch3451 I wonder if there's a way to make this work properly like it was supposed to with how far tech has come

[@isaakwelch3451]

@@kobra6660 through an external ecm I dont see why not

[@kobra6660]

@@isaakwelch3451 maybe one day I'll find out if I can get one

[@michaelhungate2047]

It's absolutely amazing that 8-6-4 still works. These were famous for not holding up past 30,000.

[@Schmuly]

I hope they at least broke on 8cyl lol

[@lucyfan1976]

This car was working just as it intended. Unfortunately with GM they come up with some great ideas and designed but the quality and putting the plan in action always fell apart. Plus the computers were not yet there. They were however ahead of their time with this car. Years later now Chrysler, Honda is doing cylinder deactivation and it works great now with the advancement in computers.

[@imzjustplayin]

It functions but long term, cylinder deactivation damages the piston rings requiring an engine rebuild.

[@austinsmith6714]

GM is still doing DOD (displacement on demand) to this day and it's still awful. Engines equipped with the technology are very prone to valvetrain failure.

[@tbah9402]

GM tried it again and now there engines struggle to get past 50k without destroying the camshafts and totaling the engine

[@tbah9402]

@@imzjustplayin no it doesn't if a mds solenoid goes out a lifter will collapse but if you replace it right away then no damage occurs but most people just delete the system it only saves 1mpg on a good day

[@imzjustplayin]

@@tbah9402 the solenoid has nothing to do with piston ring failure/gumming up. ALL vehicles with VCM have this problem so anything that has to do with the solenoids or valvetrain is a completely separate issue.

[@ChevyBM]

These are really interesting cars, the problem with the 8-6-4 is that they relied to much on electronics that was not so reliable at the time it was made..

[@RADIUMGLASS]

Yeah I agree the technology was new at the time and you just don't know whats going to fail until it fails. A lot of electronics were put in cars in the 80s many failures.

[@ChevyBM]

But it would be cool to own one that works!

[@gillesdouaire6616]

Actually, after changing a couple of sensors (TPS and O2) the car runs much better. The two were bad, but did not get error codes for them.

[@GaryJRanno]

i worked for Cadillac in 1981. they were far aheaf of there time. the shut off the valves to eliminate the skip of a dead cylinder. the Tps was an issue and the 6 cyl mode was alittle rough. coupled with a brand new converter clutch transmission it felt like it was skipping.

[@motor-werner1989]

But with todays electronics, you could make this System reliable... ;)

[@LMacNeill]

Way ahead of its time. The computers just weren’t smart enough to deal with this properly in 1981. Most folks just disabled the system and lived with the poor fuel economy. Very surprised this one still works!

[@dirtyaznstyle4156]

I dunno if it’s ahead of its time, I don’t think cylinder deactivation is a great way to improve gas mileage to begin with.

[@friendlypiranha774]

LMacNeill - Yes, 1981 was a long time ago, and also just yesterday. When these V8-6-4 Caddy's came out, IBM was still getting ready to introduce the 4.77 MHz IBM PC to the world. And that is a whole lifetime ago.

[@MrSpacelyy]

@@friendlypiranha774 4.77mhz is fast enough for this

[@bubba99009]

The constant switching between cylinder counts at that speed reminds me of the old days when some cars just couldn't decide whether to stay in overdrive at certain speeds or not and would just keep going in and out.

[@Darrell1981]

Especially come across a hill, I got my but chewed for down shifting " hey this isn't a standard let the transmission do it's f***ing job".... Eventually I figured out 76 mods was a lot different than 90's.

[@tostadatheviking7828]

@@Darrell1981 Actually, you are supposed to get out of overdrive when you're on a steep hill because the transmission will keep switching between gears especially at higher miles

[@Darrell1981]

@@tostadatheviking7828 seen someone do that in a older Caprice, but it was three speed. He would shift down going into town where it was 25 mph, something to do with not wanting to lug the engine. The 76 Ford was really screwed up thanks to my dad🙄, he acted like touching the shifter would blow the transmission.

[@Jo_Wick]

My late 2000's toyota still does that when it climbs a hill. Really annoying, but at least I can force it into overdrive so it doesn't switch fast like that.

[@engihere5434]

If I'm going 40 or below in my truck, I set it in drive, if I'm expecting to go faster, I set the shifter in overdrive

[@fuji302]

I remember in my college (trade school) class we were talking about emissions and CAFE and our teacher started talking about this because GM would be doing it again. He said it failed miserably because the engine technology at the time couldn’t handle these misfires and it would ruin these engines. My class was run by Ford and he had talked to some of their engineers and they said they considered it but they figured they in the long run that building more efficient engines with smaller displacement would be a better route than big engines running poorly. A modern solution rather than the late 70’s 80’s bad idea. That was back in the early 2000’s. It is neat seeing one still working today.

[@TheWallsocket]

Funny cause 20 years later Ford is now doing cylinder deactivation on their 2021 5.0 v8

[@DesertSessions93]

@@TheWallsocket and foreign markets already had turbo low displacement high efficiency engines in the 70s/80s

[@tombstone5860]

CAFE in my honest opinion was a shit government policy. Pollution control is something I can get behind, especially when you look at old photographs of Major cities covered in smog. CAFE is stupid because I believe that the Market should decide whether or not to buy something fuel efficient. They were already competing with foreign cars anyway. Besides, the Ford F150 pickup truck was always the best selling vehicle in America for decades regardless of the price of gas.

[@punker4Real]

my LARGE v8 6.0L (AFM disabled)can get 31mpg but gotta be feather light on the gas and that is at 38mph

[@tjwatson0403]

@@tombstone5860 the market doesn't consider effects like climate change so a market based solution doesn't work

[@mbarker_lng]

This idea was too far ahead of its time. The technology was faulty and major engine problems were common. A co-worker of mine told me he worked in a building behind a Cad dealership and from there you could see the dealer's backyard. It was a sea of these failed engines strapped to pallets awaiting shipment back to GM.

[@peterrivney552]

They went back to sea as boat anchor's just another way GM riped people off with junk and the sad part is they are still doing it today ...

[@scdevon]

Yep, and after that it was the era of HT-4100 failures. HT= "Have Two".

[@subvertedworld]

The cylinder deactivation now is absolute junk as well. Nothing has changed. GM engines with AFM will choke and destroy themselves because of the lifters. Cost me $10,600 for a new engine in my wife's 2018 Silverado with 95,000 miles.

[@iluvcamaros1912]

Perhaps it's true, but the V8-6-4 was in reality a reliable old pushrod Cadillac V8 once that system was deactivated. It would have made more sense for those to be Olds diesel V8s or early HT4100s. Those were properly "bad" engines.

[@davidduplessis7800]

Those failed engines were undoubtedly the HT4100's that came out in 1981-1982 (replacement for the V8-6-4 and the conventional 368 V8). The HT4100 was the worst engine Cadillac ever made. The V8-6-4 was mechanically a bulletproof engine; most of them simply had the multi displacement systems removed and ended up running trouble free forever after that.....

[@Torch4Life]

My 2014 c7 z51 gets 32.5 mpg at 70 on the highway, calculated. In 4cyl, entire tanks calculated. I had no idea the tech was here in 1981, thanks for this video Gilles Dousaire. Cheers.

[@VitoVeccia]

These where unique engines. I have only worked on one of these, and that's the way I want to keep it. The electronic solenoids under the valve covers used to go bad Alot. People would unplug a connector on the transmission to disable the 8-6-4 system. They also use a vacuum pump from the diesel engines. This was to supply vacuum to accessories like the brake booster, when in deactivation mode. And the oil filter screwed directly onto the oil pump, which was external to the engine. To my surprise, the car I worked on still had the plastic timing gear for the camshaft ( they used to go bad Alot in the 80's).

[@williscurry6557]

Thats alot of car (& strain) with a 2.41 in the rear for a plastic timing gear. (gasp)

[@longbow6416]

That thing had to be a marvel of (over) engeering.... and complexity!

[@TeeroyHammermill]

@@williscurry6557 : Lots of engines had plastic cam sprockets back then.

[@aspecreviews]

Solenoid-actuated disconnecting rocker arms definitely sound like a better idea then hydraulically actuated collapsible lifters that always fail.

[@TeeroyHammermill]

Nice work. I've never seen the V864 in action like this. Great Job!

[@peterrivney552]

That because all the rest are in the scrap yards the guy that had this one parked it in a garage and just brought it out to wash it has less than 2500 miles on the odometer

[@jmmjjmmjjmmj]

i think adding 864 cylinders is a bit much

[@michaelhorn4540]

I just started out as a mechanic at a Cadillac dealership in 1982 and I remember these cars. They weren't that bad and the engines were far more reliable than the ht4100 engines that replaced them

[@mcrowley8460]

yep the 4.1 struggled to go up a bridge span without gearing down.

[@choppersports]

I call the 4100 the high technology turd lol

[@LakeNipissing]

The Cadillac 368 V8 was actually a very good engine, I believe it was based on their 472, but maybe I am wrong. The problems with the V8-6-4 system weren't due to the engine itself.

[@reginaldbowls7180]

The “high tech” 4.1 was the worst!!!

[@messemphanger]

Ahh yes, the ol'e 4100 hook and tow.

[@LakeNipissing]

One of my teachers in high school had a 1981 Eldorado with the 368 V8-6-4 engine. He had the mechanical service manual and the electrical manual, which he stated was the thickness of a large phone book! It was a great idea (and essentially what Chrysler uses in their Hemi MDS system today), but the technology was far too advanced for the reliability of 1980s electronics and mechanical cylinder deactivation.

[@alexl.4170]

"It definitely needs some tweaking still. I'm not sure how this is supposed to work." It never worked. Not in 1981. Not in 2020. XD

[@JeffDeWitt]

Oh it DID work, just not all that well, and not all the time.

[@waltbullet1287]

Its still crap got it on my vette and try to bypass it

[@ArthurBrinkman-c5z]

Most had to be set to bypass the 6 and 4 and run on all 8 full time. They drove like a dream though.

[@gillesdouaire6616]

indeed. and from a technical standpoint, the 6 mode does not make sense - it's unbalanced and vibrates. seems like 6-cylinder mode was there to please marketing :)

[@williscurry6557]

& drank lots of gas. A money-green 81 fleetwood was parked back at the buy here pay here on its 2nd wk out. Fuel econ was 8 mpg at best but it was soo smooth!

[@punker4Real]

@@williscurry6557 6.0 LS2 swap is in order I know they got a 5.3L short block in the impala SS, caddy this was FWD correct?

[@cliffordkiehl3959]

I'm glad Gilles made a clip of this working. I think it's the only one that ever worked. Needed more advanced sensors, the computers of the day were probably OK.

[@Phos9]

I don't see why they bothered with the six cylinder mode, a v8 fires every 90 degrees and a v4 fires every 180 degrees, but in v6 mode it's going to be firing odd.

[@gillesdouaire6616]

Phos9 Indeed. There's probably a marketing reason behind the 6-cylinder mode :)

[@thethomasj1795]

That's why it runs rough.

[@notsure9079]

@- Ashai - odd fire buick v6, was replaced by the even fire lol

[@pcno2832]

@- Ashai - Yes, that was the easiest way for Buick to cut its "nailhead" V8 down to 6 cylinders and it stayed odd-firing up to mid-year 1977 when they used split crank pins to make it almost even firing. I say almost because you can't get perfect balance and perfect even-firing from a V6, so most such engines are a compromise between the two goals.

[@keegenm.6154]

@@pcno2832 wrong, the buick v6 was built off of the design of the aluminum 205 v8, which is not a nailhead

[@guerrillaradio9953]

I'm glad yours still works! Mine was disabled long ago, and still runs really great. Still manages about 23-24mpg highway at 70mph with cruise control on. The very high gears in these cars really make the system unnecessary, honestly. My v6 Impala gets the same economy... and it's much less comfortable 😊

[@cardinaloflannagancr8929]

That's a good point even on the modern versions of this by various companies they overlook all the logistics. They overlook the likelihood of decreased engine life, making, maintaining and replacing those extra "mileage saving components" Instead designing their systems more around how the epa tests and theoretical not actual driving styles which vary. Then add stop start which uses several methods to operate. Some use a primary then a secondary starter for the stop/start function. Others use transmission pressure to help turn the motor over easier. They virtually all ignore the drain on the battery which starter batteries dont like. That most engine wear happens, at startup which now doesn't only happen when say you leave for then return from work. Rather anywhere your stopped for more than a few seconds so not 2 starts now maybe 8 or 10 even on a short drive.

[@guerrillaradio9953]

VERY good points! Cars stopped being about delivering any sort of value to the buyer and ONLY about delivering to the board of shareholders a long time ago. It's just as well that newer cars cost an exorbitant amount of money, because with how overly, needlessly complex and unreliable they are (not to mention they all look exactly the same and are HIDEOUS), I wouldn't drive one if you gave it to me.@@cardinaloflannagancr8929

[@aspecreviews]

@@cardinaloflannagancr8929 there are 24 year old hybrids that still run perfectly.

[@MBVTemjin]

I really dig the luxury boxes of the 80's and I honestly want one of these now, even if it is a nightmare to deal with.

[@erickricharson5196]

I had one. The cylinder deactivation crap was disconnected and it was a strong engine. Great car

[@RussClarkRocks]

My old man had one of these Caddies when they were new. Black Fleetwood Brougham with tan leather interior. Beautiful car. He always had great cars.

[@midway27272727]

We had a number of Ford V10s that would deactivate cylinders. How Ford accomplished this was the valve keepers would fail, the valve would collide with the piston. More of a permanent de-activation but it worked. When you wanted to go back to all 10 cylinders you'd order a long block and do an engine swap

[@rickylexy]

😂😂

[@kimberlyx4060]

Thanks for showing this. I drove this model once and a while as a teenager. I enjoyed it, and it was ahead of the times.

[@Marshallmiracles]

That was fun watching the cylinders deactivate. That hot good gas mileage, too! If you were coasting down hill on the expressway, the mpg would jump to 60 or so.

[@mosmotorcyclejourney9067]

Yep it's working properly. The way it was made too. And it didn't stick around long because they never perfected it. Like you said it runs rough in 6 cyl mode. So they did away with it. However I believe they have the technology to bring it back and perfect it in today's world. Be safe and I haven't seen one of these in a long time. Thanks for sharing

[@Tex777_]

Really cool to see. I love car tech that was ahead of it's time

[@sirspamalot4014]

Everyone saying the computers were the problem when it was more likely the sensors. These would've been analog sensors for everything, some stuff is still analog in modern cars, but the way the signals are carried is super important in a car, and if the sensor power feed isn't filtered from the electrical noise generated by the alternator and ignition coils everything's going to get wacky quick. Analog doesn't like small interference, and cars are one of the best generators of electrical interference out there. really cool to see this running, and working, I'm sure there's tweaks that could be made to the system with modern knowledge to make it work how it was intended.

[@JoeHynes284]

you are probably right. Most commentors here get all there info from wikipedia

[@noscwoh1]

The 8/6/4 was a brilliant design. It was a simple work around for the legendary Cadillac big block that might have kept it in production until the 21st century. The cylinder deactivators were solenoids that decoupled the rocker arms from their pivots. Rugged and simple. There were only two factors that let the system down. One was trying to make it seamless from the driver's experience. It would have worked MUCH better as an 8/4, with an obvious sense of "you are now in MPG cruise mode." As it was, it spent too much time hunting around 6 cyl mode, which is inherently odd-firing and "feels wrong." The second factor is the lack of computer processing speed in 1980 to make the number of corrections per second that the 8/6/4 needed. With an 8/4 as previously mentioned, there would be fewer transitions, and there would be a little lag, but no worse than a turbo of the era. In just a very few years, certainly by '87, with the addition of direct injection, lean-burn, and faster processor tech, the 8/6/4 would have been completely amazing.

[@cardinaloflannagancr8929]

Very true they were trying to do too much and rather quickly as well. Similar to how annoying the 8 and 10 speed transmissions are, constantly hunting gears. The first time I drove my brother's new 10 speed suv I thought the transmission was broken.

[@brianethridge208]

I was a mechanic around '91. worked on lots of used cars for the lot next door. I dont remember EVER seeing one of those things that still worked!

[@HIDHIFDB]

All of them hacked to be in 8 mode always just like the new silverados GM never changes

[@MichaelFlatman]

Main issue is the EGR on these i think, it's a simple backpressure type valve (no computer control), 4 cylinders at higher load requires more EGR than 8 cylinders running at lower load, but unfortunately 4 cylinders produced less backpressure than 8, causing less backpressure & less EGR than intended. This caused a 'slight misfire' as the air mix wasn't quite right, unfortunately with this type of valve & the technology at the time, it could never be right (until more complex computer control was a thing) Wikipedia article is interesting about this engine, apparently you can use the climate control display to view fault codes & do self test, pretty cool for 1981!

[@gregorymalchuk272]

I wonder if you could lock it into 4 or 6 cylinder mode. I know you could force it into 8 cylinder mode.

[@DavidPysnik]

Very interesting as I've never seen the V8-6-4 in working order before, so thanks for sharing!

[@RupMan84]

Thanks for the nostalgia. My parents had an '81 Caddy with the 4-6-8. It was and still is the smoothest riding car I've ever been in.

[@420architecMindNDesign]

This is very cool to see still working

[@brendanzio]

wow, thats really neat that they had systems like that in the 80s, I never knew about that

[@ryanjohnson8821]

My dad had an '81 Coupe de Ville with the 8-6-4. He was a mechanic and deactivated the system shortly after getting the car. He drove the car for about 10 years, then handed it down to my brother and he handed it down to me. All on the original engine

[@davidmacpherson857]

Wow, super cool to see this tech so long ago. Thanks for taking time to share with us

[@gillesdouaire6616]

My pleasure. Before owning the car, there was no video of this in action on youtube, now there's a couple :)

[@wilsonle61]

I agree with Michael K, computers and solenoids, etc just were not there yet. Thanks! for sharing this wonderful and unique old piece of technology! I remember them being advertised on TV but never saw one in action!

[@jasonmurdoch9936]

Actually the solenoids were fine the computers were not

[@jamesadams2333]

That’s amazing watching such a classic system work like that. They should’ve went with sequential injection for this system I always thought. If I recall it was throttle body injection and they had problems with fueling or something like that being another thing. It’s still amazing it worked and I’ve always been curious about these cars! Computers have come a far way. Especially for the deactivation technologies of today. Well done!

[@mikevan5219]

I was in my early twenties as an technician. This system and the crossfire injection in the berlinatta and corvette were new systems. On paper they worked in relatively they didn't. But it was a whole new body style. It was an education curve for the engineering department ov general motors.

[@misters2837]

One Major problem with early 80's American Automobiles is, when they did the fuel economy testing for these they used a Dynometer and Calculated the economy in unrealistic ways...and one of the ways to get Fantastic numbers were to install very high speed (Numerically Low like 2.4:1) axle gears, which wasn't really a problem when combined with 3 Speed Transmissions, but sometimes the manufacturer would get so greedy that they would put those gears in combination with Overdrive Transmissions...It would be fine on the Dyno, but in the real world it makes the engine run at a speed that is under its optimal speed for Mileage... A Good Example of this, I had a Low mileage (55,000 Miles) 1987 Chevrolet G20 Conversion Van, it had the 180 horsepower, TBI 350/700R4 Automatic Overdrive Transmission, Not a bad combination in the Days of 55mph National Speed Limit, it had a 3.08:1 Gear Ratio...and if you drove it 55-60 on a windless day (any headwind and forget it!) the van would get 18mpg with the A/C cranked, lumbering along at 1500RPM...Not Bad for a 5000lb brick...Now Fast Forward 15 years and we have 70-75mph freeways, now try to take that Van up to 75mph on the freeway, and you find it didn't have QUITE enough horsepower/torque at now 1900RPM to push that same brick 15-20mph (25%) faster because it now requires almost double the horsepower...And with 400RPM increase, it's not even close, So then the throttle setting is calling for the transmission to hunt between Lockup of the Torque Converter and or 3rd (Direct) gears, eventually that hunting will destroy the transmission...Now had that van had 3.73-4.11:1 Axle Gears the engine would have been turning 2300-2500RPM At 75 in Overdrive, and making much more torque and Horsepower...and would have handled the wind resistance much better, and while in 3rd (Direct) it would have made the Van a much more capable tow vehicle. See what happened was when the transmission shifted into Overdrive with 3.08:1 Axle Gears it was changing the final drive ratio to 2.16:1 crazy highway speed gears...whereas the 4.11 ratio in Overdrive would be an acceptable 2.88:1 (Many Ford Vans Made thru the 70s-80s did not have Overdrive Transmissions and therefore came with 2.75:1 Axle Ratio as a compromise for HWY MPG...) I suspect your transmission and axle ratio is just at the point where there isn't enough horsepower/torque in 4cyl mode to maintain a speed even of 80kph on the flat, I doubt it would even at 100kph as the wind resistance on that big boat of a car is going to require too much power... It's interesting that the 6.0L engine is related to the 8.2L I wonder if they hadn't had a better computer system and used the 8.2L engine short block, with the 6-V8-4 heads, if it wouldn't have worked better? After all the 4.1 V6 was notorious for decent MPG in those Caddy years, but overall Gutless!

[@alexandermoore2982]

good read, this is something I hadn't considered. you always hear older folk talking about 'how comfy those old cars were!' for highway cruising but it's easy to forget we all drive way faster now.

[@SUPRAMIKE18]

My grandads 1979 Chrysler Newport used to do that around 70mph the transmission was constantly going back and forth, you either had to trundle along at 55 in the right lane or (what my grandad usually did) gun it and cruise at a comfortable 90mph.

[@alexandermoore2982]

@@SUPRAMIKE18 that also answers my question of why my grandfather primarily drove his B-body Impala above 85 mph

[@SUPRAMIKE18]

@@alexandermoore2982 yeah as strange as it sounds driving cars of that era faster is actually better for them (the transmission anyways, the fuel mileage is another mess lol)

[@punker4Real]

a few aero mods on the brick would take care of the issue

[@michaelbenardo5695]

Amazing that you have it working as intended! My hats off to you!

[@tavi9598]

This is amazing. Most of the cars featuring the 8-6-4 system had it hard set to permanent 8 cylinder mode back in the 80's. The computers of the day simply weren't up to the task of on-the-fly engine management like that. The processing power was just too slow. The idea was way ahead of its time.

[@93sundance]

I had one come into my shop a few years ago. It had been deactivated but all the parts were still there, never thought I would ever see one.

[@gillesdouaire6616]

They are becoming scarce by the minute :)

[@DJBiv788]

Wait…active fuel management was around back then?

[@HamiltonMechanical]

my friend had one, but he never got it back together. I had never heard about it until then. Its not well known, but the chrysler 5.7 hemi is a 4 6 8 motor. 28 out of a Caddy? that's awesome man! Great job :) It may not have been successful when it was new, but if everyone ripped it off and stuck a regular carb on it, there wouldn't be any left for us to appreciate.

[@charlesbutler4646]

I bought a 1981 Cadillac.. After a month I had it fixed so fixed so that it stayed on 8 cylinders 8 cylinders it was a fantastic engine . Answer is yes it is supposed to shift In-and-out of Four and 6 and 8 mode Frequently. Several times a minute . For a while it was a novelty and then it drove me crazy and I had it straightwired to stay at 8 cylinders . I still got excellent gas mileage And the car ran beautifully. I wish I had it back.. I Traded it for A jaguar.

[@gillesdouaire6616]

I have always felt that cylinder deactivation on this engine feels the same as misfire/near-stall...

[@cardinaloflannagancr8929]

Yeah the electronics were an issue but if nobody tries anything new there's no progress. It is still a good idea and it was decades before being tried in a production car again. Another thing starting this year as well maybe 1980 was the built in code scanner, many owners don't even realize it. One nice thing is the ability to clear the codes when your diagnosing a problem. When I bought my 03 there was an engine light on for crank and cam sensors. It turned out to be a known issue and they had been replaced but the seller thought only a dealer could clear the fault code.

[@bruschmidt9943]

Wow, yours functions better than the brand new one I drove at the Dealership back then. Mine was usually in '8' & VERY seldom in '6'. I never saw '4' come up on the gauge.

[@kobra6660]

I wonder if there could be a way today to actually fix the 8 6 4 cylinder deactivation and make it work perfectly like putting a button option to choose which mode you wanted

[@TOBYH]

I am not sure if they still do the cyl deactivation, my friends 2005 Honda Odyssey had it it would deactivate 3 of the 6 cyls

[@samstrolia]

My coworker told me about this and i couldn't believe it! Very cool!

[@goldenboi7685]

When his miles per gallon dropped below 13 I felt that. My 86 Fleetwood Brougham de Elegance average about 12.7 mi to the gallon. Unbeatable ride quality though

[@kenbowser5622]

I had an 80 coupe DeVille that got close to 20 mpg. Had a Chevy 350 in it. Also had a 93 sedan DeVille that got 24 with a 350. Both were overdrive tranny's and great cars. My 77 DeVille with the 425 got like 10.

[@goldenboi7685]

@@kenbowser5622 best I got was 15.5 in a '96 Fleetwood Brougham with the LT1

[@kskip4242]

@@kenbowser5622 you're full of s*** I don't believe you. The 93's we're still front wheel drive with a 4.9 v8,no way it had a 350 in it. Try again.

[@altacat9702]

Thanks for posting this and real fun to see it work !! ...as you know it didn't work out but way cool to see it in action : )

[@JCCruising]

Awesome technology for it's day. Cadillac always seems to be ahead of the curve for new stuff. I love my Caddy that is also an amazing car,

[@zacharyk7225]

This is amazing. You have an awesome car my dude.

[@bencebaumgartner1320]

Nice job sir! Yes it is important to save these cars for the future. Do not bother with trolls.

[@tomwebber9377]

Mr. Anderson, I agree! What did it cost to get that system up and running again? Of course there would be shake, the engine is operating all over the map with activation and deactivation. They just didn't have the technology then to pull this off. Today they just gave up displacement and turbo charge the smallest engine possible and drop it in. I have gone plug in hybrid and thrown in the towel on every owning an actual basic performance car.

[@InnercityHillbilly]

I used to have an old slope back Seville with this system. The computer was messed up and it ran on 4 cylinders at all time. Sounded like a choo choo train and was from 0 to 100 kph in 4 minutes LOL

[@gillesdouaire6616]

I bet running on 4 cylinders while accelerating (or trying to accelerate) also resulted in very poor gas milleage :)

[@InnercityHillbilly]

@@gillesdouaire6616-HA! I don't ever remember recording any fuel economy records. I member inside it said it was getting 18 and 21 miles per gallon. I said kph because that's the way that you guys are registering your speedometer in this video. I think it's funny that here in the US we say 0 to 60 time and in the UK they say 0 to 100 time

[@InnercityHillbilly]

@@gillesdouaire6616- I thought it was a throttle body problem whenever it turned out it was a computer problem

[@gillesdouaire6616]

computer, wires, sensors --all terribly fragile on this car. wonder if the older Bendix injection on Sevilles was more reliable?

[@InnercityHillbilly]

@@gillesdouaire6616- everybody that I've known that has had the coveted box body Seville and 442 Oldsmobile with the same system has replaced them with an aftermarket throttle body injection and intake

[@pcno2832]

I read somewhere that there is a way to make it skip the 6 cylinder mode, since the 4 and 8 cylinder modes are both smoother. I'd expect that to reduce the number of mode shifts too. But I have no idea how the modification is done.

[@gillesdouaire6616]

That would be great to skip the 6 cylinder mode! :)

[@vilefly]

This is fairly normal operation, but it might be helped by adjusting the transmission's vacuum modulator valve to keep it in 3rd gear instead of allowing upshift to 4th gear at part throttle. I remember installing the two prom chips when updating the computer. There was an A and B chip. Many people simply override/unplug the computer with a switch that switches it to 4 cylinder mode and skip the shaky inefficient 6 cylinder mode. The computer simply wasn't fast enough to adapt to changing load conditions present when going up and down hills. Basically, they wired up all the valve cover plugs to a switch, and unplugged the computer from them. What most people don't know about the cadillac engines, is that you can bump base timing to oldsmobile specs without detrimental effects. Setting the base ignition timing from 10 deg. btdc to 23 deg btdc made a huge difference on power and economy. Quite a leap, especially on the 500 cubic inch motors.

[@kingofthepod5169]

Well preserved ride. Thanks for keeping it running.

[@chadhartsees]

That's amazing. I didn't know anything like this existed in 1981.

[@peterj5751]

Does anyone know how this was implemented by GM at the time? Did it just cut fuel to cylinders? The problem with being first is that you find out the problems first too.

[@CH67guy1]

When did Cadillac go with P R N D 3 2 1 on the gear indicator? I thought it was always Drive 1 Drive 2?

[@jerrysgardentractorsengine2243]

No idea why this was recommended to me, but I’m glad it was

[@gillesdouaire6616]

the mystery of the youtube algorithm...!

[@jerrysgardentractorsengine2243]

@@gillesdouaire6616 real talk man, it’s amazing that there’s still fully functioning 8-6-4 Caddy’s out there.

[@shaneschlievert5492]

In the US people didn't like the 864 system because of the rough engine operation in 6 or 4 mode so almost every one had it disconnected. It's just a plug at the distributor to disconnect it.

[@MikeNebgen]

I appreciate the video. I always wanted to get one of these cars and mechanically restore it just to see how it feels when it switches modes.

[@zeon5323]

Back in the day, we had customers with these cars and they wanted that system disconnected. Just unhook the brown wire at the transmission and the car will stay in V8 mode. Remember in 1981 people that bought these cars were not concerned with MPG they wanted smooth.

[@michaelbenardo5695]

AMEN.

[@prosperity4444]

Its 2022 and gm still can't get cylindrr deactivation right

[@TonyFleetwood]

a euro model 8-6-4 at that must be very rare! i wonder if a modern arduino or something could be used to replace the original computer to add better reliability?

[@mjobermeyer09]

Cylinder deactivation is a bad idea in general. It causes uneven cylinder wear and tear.

[@readthebible1958]

I worked on these engines at Arnold Palmer Cadillac in the 80s. They were good engines. They had plastic valve covers which always leaked oil.

[@gillesdouaire6616]

Yes, these plastic valve covers are very hard to find these days. I had to patch a big crack on mine using fiberglass... worked well!

[@readthebible1958]

@@gillesdouaire6616 Yes, fiberglass works well. I also worked on HT 4100. Seems like I replaced 4 to 5 camshafts every week. This engine along with the 200c and 200 4R kept me busy. Good day to you.

[@3picmotivation]

Yes it's deactivatibg the cylinders as frequently as needed, it runs quite well. Good find.

[@Taydrum]

When it's in 6 or 4 cylinder mode does it skip every other cylinder? how does that work? Does it fire the only same 4 cylinders?

[@87fordmustang]

You win today's KZbin lottery; not sure why this was on my feed, but have a like anyways!

[@gillesdouaire6616]

I am not sure why this video gets so much traffic, the algorithm is mysterious!

[@ghazibagazi9687]

Sir how can I do such this action on my car fleetwood 1983 4.1L .please axplen?

[@jimmypage4162]

I’ll hold out for the 5.0/5.7liter cars. Yes they shift through V4-6-8 quickly through back and forth. Seriously probably the last functioning one in existence! My first car 1992 Cadillac fleetwood brougham 5.0 one owner 76,000 miles I’ll miss that girl till the day I die.

[@jessemazo4791]

i love these old caddilacs ..keep her runnin for sure

[@TheMW2informer]

I have a 2007 LTZ Z71 Silverado and I’ve always liked its “V8 Mode / V4 Mode” who else can say they drive a V4! I have a question about that display that shows the current mode and MPG, is that all it displays and when driving how noticeable is a change if your not paying attention to what mode it’s in? In the ‘07 reincarnation of DoD it’s just about unnoticeable except for rare highway situations and it’s never a problem, for instance I can step on it and no delay it’s launched.

[@gillesdouaire6616]

The changes between cylinder modes is very noticeable - almost like the car is downshifting or hesitating. But I am not sure if this is per-design, or if this is because my car needs more tuning and tweaking.

[@WymiataczPlays]

My uncle had a ZAZ 968 Soviet car with a V4 :)

[@apl175]

It's so interesting that in the USA they called the little computer the "MPG SENTINEL" but this would not sound right in metric countries so it became the "ECONO MINDER". When the HT4100 was introduced, it changed again to "FUEL DATA" - which presumably worked for either standard of measure.

[@davidaix5771]

What is he talking about what's 864 mode and what's that little Display with 4 buttons that hes touching

[@Hansengineering]

Amazed at the feature set they had there in the 70s!

[@GGwasEZ]

I know it's been 5 years since you put the vid up, but if you've been in a modern Chevy Silverado since this, they do the same thing. They shift just as fast depending on the power you "need". (What the computer determines is needed based on multiple factors, including if you are towing and hauling, if your tires are spinning, how much you depress the gas pedal, many many things, and there are sensors for everything now, so the computer knows and it trying to accommodate to what you are doing) This is early 80s tech trying to send power to the engine based on how you drive. It wasn't good tech to begin with, and you've had it for longer than it's due date lol

[@CEOkiller]

When does it go into Breakdown Mode?

[@gillesdouaire6616]

When not maintained properly 😅

[@wincrasher2007]

there is a way to manually change the modes and have them hold in them.

[@gillesdouaire6616]

yes, with the special diagnostic feature, you can force any cylinder mode. but it's really made for troubleshooting, using it as a standard feature would be pretty unconvenient - holding buttons while you drive, etc...

[@FuquarProductions]

6 years later, how is the car doing?

[@__chevytrucks__]

Oh, so it changes the amount of cylinders being used? That’s kinda cool, but what would be the benefit of that?

[@artlife6210]

wow, just wow, thats impressive it still works!

[@CheesusSVT]

Very neat. Thanks so much for sharing this with us.

[@SPEXWISE]

That old stereo brings back memories. Symphonic Sound System. I think my dad had one in his old Ford Grand Marquis, thing was a boat on wheels and the stereo was shit.

[@gillesdouaire6616]

I think Ford even pushed for the Quadraphonic 8-track players...!

[@fredcloud9668]

The temperature fluctuations were hard on the engines.

[@mikemintun1587]

This should have been called the 8-6-4-0, as it spent most of it's time at Zero. This was typical General Motors. Under engineered, rushed to market and road tested by the consumer. What junk.

[@kskip4242]

Only the technology on this motor was bad the motor itself was good. The 368 just a destroked big block v8 caddy. Stop acting like all the other manufacturers during this era weren't pumping out total shit, because they were.

[@mcrowley8460]

I bought a very nice 81 brougham coupe white with drk blue velour int astroroof the 8-6-4 worked fine on my one hour drive home. After that it never went out of 8 cyl ever again till i sold it.

[@wannabeetiger]

And GM still has not perfected the Cylinder deactivation feature!

[@richb.4374]

An idea ahead of it's time. Now the modern engines have displacement on demand and it's smooth and seamless in operation.

[@fargeeks]

I heard that for the non firing cylinders in the engine they wear unevenly

[@gregorymalchuk272]

This is a really cool car and a cool example of technology that was ahead of its time.

[@user-bc7nx7nr8o]

I would want to try this out and see where I can cheat the engine into 4-cyl mode more often.

[@nlpnt]

Is the mpg readout in Imperial gallons since this is a Canadian-market car or is it still in US gallons?

[@gillesdouaire6616]

US, because by 1981, it should have been metric in Canada / this is clearly an all-US system adapted "as is" in Canada. They just changed the name on the bezel, in the us it's "MGP Sentinel", in Canada it's "Econo Minder".