Cadillac HT4100 Engine Assembly - Service Roundtable Laserdisc

[@saganich74]

The old Hook and Tow 4100

[@joe6096]

Oh my gosh! it's the HT4100!!! The nightmare of the 1980s Cadillacs!! GM will never recover from the perfect trifecta they released in motors from 1979-83...... the Olds 350 Diesel, Cadillac V8-6-4, and HT4100. Came this close to destroying the Cadillac brand forever. Thank you to whomever uploaded this video. Might be the most prophetic video on youtube. 0:37 - "This system is responsible for catching any possible substandard conditions" GM started this comedy show with a great line right off the bat!

[@yamajammer76]

Yeah and for the opening act they gave the world the Vega 4 in the 70s. Lol

[@SnepperStepTV]

LOL you have no idea what you're talking about, just sensationalist gibberish.

[@allentoyokawa9068]

Best engine ever! Powerful, smooth, quiet, fuel efficient and most of all extremely reliable! Fun Fact: It is so good, that all of today's best engines are based off this exact platform! Thank you GM!

[@edwardpate6128]

I am sure glad you have a sense of humor!

[@Toolaholic7]

It was a pos,headgasket and camshaft failures

[@johneckert1365]

You are insane

[@allentoyokawa9068]

What??! This is a HAND-BUILT MASTERPIECE! 🤯

[@Toolaholic7]

@@allentoyokawa9068 The camshafts in them were too soft.My dad has replaced one because of headgasket problems

[@neilouellette3004]

Owned a gorgeous 1983 Fleetwood Brougham d'Elegance Coupe w/only 30k miles back in 1985-86. That Hook & Tow 4.1 motor was junk. Broke down non-stop all the time. Got rid of it after 6 months. Never went back to Cadillac after that.

[@RhYmEnRyAn]

I have a 30k mile 83 fleetwood brougham de elegance with 4.1 and runs perfectly in 2024

[@johnfranklin5277]

I ha 5:46 ve my Dads 83 Eldorado, these were beautiful cars inside and out. It has its original Ht 4100, 147.000 miles, no problems with the engine, runs smooth, sounds very good. 3000 mile oil changes, and coolant exchanges every 2 years, and coolant tabs ALWAYS at every coolant service. The engine has never been touched.

[@LowEnd31st]

You’re the only one with the original 4100 trust me 😂

[@Beechboy68]

​@@LowEnd31st no one gonna trust you. My 83 Brougham still running strong 41 years later. Now what

[@auntbarbara5576]

These engines were so smooth and quiet. Especially when they were dead in your driveway.

[@charlespierce3647]

Owned an 84. While in warranty 2 engine replacements, rack and pinion replacement and it was knocking again when I got rid of it.

[@askjeevescosby2928]

I get this is a bad engine. But I can't bring my self to swap it out of my seville. The engine is the heart of a car. This video made me want ti get it rebuilt and get all that polished chrome on it. I would most likely have some company machine me new heads.

[@AJ-170SkyStriker]

I have an 85 Seville and while the video showed how intimidating this rebuild would be due to modern supplies being different, I still want to rebuild my 4100 too. Maybe even change some parts to make it more reliable if possible.

[@patrickmcgoldrick8234]

This was a gate way to the Lincoln Town Car,it was nice of Cadillac to help Lincoln,or any other luxury car maker at the time that sold a car that had an engine that exceed the durability of a soaked donut.

[@303nitzubishi4]

Like so many other GM products, this one was actually decent just before it ended production. My dad put over 300k on a '91 4.9 with nothing more than regular maintenance and main bearings every 50-70k. The only time it left him stranded was due to fuel strainer desentegrating and destroying the fuel pump. Neither the engine or trans were ever out of the car. That said, most of the interior was held together with long self tapping screws and duct tape by the time he gave up on it

[@mrflamewars]

Main bearing are absolutely not supposed to be a "Wear Item" - if they need replacing that often someone has seriously fked up.

[@robertcraven1771]

I’ve known of more than a few 200-300k + 4.9’s I’ve never seen that many on a 4.1, but my 85 Brougham has ~130k and to my surprise has given me very little trouble. We’ll see if that last…

[@fixinstuff9662]

Thanks for the video. Interesting!

[@mattshane1993]

I'm very excited to find this ☺️ I currently have a few of these, and they are excellent when running and kept up. Luckily for me, they are just weekend cars and in amazing shape, but this video answers questions

[@Greatdome99]

In my experience with GM engines, there's too much dependence on RTV (Room Temp Vulcanizing) sealant instead of good old gaskets.

[@johnfloyd2551]

A good quality RTV such as grey greay or ultra black.. has excellent sealing properties.. better than gaskets... A lot of modern engines.. have their timing chain covers oil pans. Sealed Solely with RTV.. when applied properly. It seals much better than rubber or cork gaskets

[@JoeMama-j7s]

@@johnfloyd2551Yup

[@avioncamper]

How many times did we hear 90 degree V8?

[@manonmars2009]

I had an '83 Eldorado with this engine and what a nightmare it was. On the plus side, the car got 26.5 mpg on the highway and purred like a kitten. Is there any place on that engine where GM did NOT use RTV? I got rid of the car and bought a new 1993 Volvo 240 which I still drive today 30 years later.

[@Bostonharborwater]

My buddy had an 83 coupe deville. Was a cool car. Smooth ride. The 4100 was such a dog though.

[@gregkellow4723]

Let's see. Oil leaks. Coolant leaks. Intake gaskets. Main bearing knocks. Sludge. Worn camshafts. Broken oil pumps. Broken rocker supports. Sticking valves. And more oil leaks. Did I forget anything? I cut my teeth on these boat anchors in the 80s starting out in a Cadillac dealership.

[@Toolaholic7]

Left out headgasket and camshaft failures

[@joe6096]

Oh, yes, you forgot the porous block castings which let coolant "bleed" right through the block lol...... don't forget your coolant pellets when changing the coolant to keep them nicely blocked (and clog the water passages it DID need in the process)

[@gregkellow4723]

@@joe6096 yeah, we called them Cadillac aspirins

[@303nitzubishi4]

I cut my teeth in the mid 90s after most of the bugs had been worked out of this design and Cadillac started all over again with a new one. Doing main bearing service or even an intake on the 4.5/4.9 engines was a treat compared to all the headaches that came in on the Northstar Sevilles/Eldorados. Ugh I'm glad those days are over

[@eddiestanley135]

Same here started at a Pontiac Cadillac dealership. Cut teeth, hands, fingers, arms and assorted other body parts!😁 Parts department had a half dozen or so long blocks in stock! Now that is quality 😅

[@airconditionerfan2283]

Thanks.

[@Athingmaybe123]

I like that there's one comment so far and for once it's not someone screaming 1st also excited to see all the comments on how good or bad the engine actually was curious if it has major failure points

[@jayson657]

It was one of the worst engines ever made. It was rushed into production in 1982 when Cadillac’s 6.0 liter V8-6-4 cylinder deactivation system ended up being a catastrophic failure in 1981. The HT4100 wasn’t meant to debut until 1985 in the much smaller downsized line of cars. But it was hastily placed into large, heavy full-size Cadillacs to meet government mpg CAFE standards. The various metals used in the engine were not compatible and caused the head gaskets to leaks and fail, head bolts would tear out of the soft aluminum threads in the engine blocks, oil pump failures and the engine was just too small and underpowered for the large cars they were being placed in.

[@Athingmaybe123]

@@jayson657 y does this not surprise me lol good ol gm it's like VW but american

[@sbechris]

10:54 Water Pump Info

[@willg.5168]

I found a cherry '87 DeVille with a 4100 in it @165,xxx miles. Im sooooo curious as to wonder what was done to it to have reached those miles(rebuild, maintenance, etc). Started out asking 5500, but now its down to 3995. If ut creeps down to about the 3500 mark, i just may get it at least for the body/interior. I can always replace the motor, right?

[@LowEnd31st]

There’s a good chance it’s been replaced or rebuilt already, even though the 87 version is allegedly “fixed” (it wasn’t). Problem is it’s getting hard to find replacements.

[@jamesb8305]

RTV instead of gaskets, straight from the factory? Really??

[@jason3fc]

Bud Haggart, nice!

[@SnepperStepTV]

What carries over to the later, refined 4.9L? The build in particular is moving in a RWD reorientation but the engine and transmission are very interesting to me, and I'd like to utilize the pulled drivetrain in something else down the line.

[@octenol9760]

A lot of it carries over directly. Really the only major differences are the timing cover and thermostat housing adapter. The 4.9 seems to use proper gaskets in place of RTV slathered over everything, as well.

[@oldguy2082]

Good grief, I hated this motor. Worked in multi-line dealership service department and when we saw one of these it was usually for blown headgaskets/overheating or leaking oil. I'm not certain which was worse, the Northstar with constant blown headgaskets/bad heads or the 4100 motor. Along with V8/6/4, not one one of Cadillac shining engineering achievements.

[@jeffsmith-ze6wb]

Your right ex Cadillac mechanic here also

[@herrbela84]

They are using speed handles there.

[@NoNo-iz8hd]

Coolant leaks, bad camshafts. Great quality control.

[@killercan10]

I can't be the only one that hates RTV...can I? What was wrong with good gaskets? Now we have plastic oil pans with RTV that leak and warp, RTV that sucks even though robots apply it at the factory, etc.

[@dwainekahicks]

Cadillac Remedy Was An Oldsmobile V8

[@gsm19911]

Followed by a Chevy V8 in 91

[@Dannyboy-nj4wh]

Late 1984-1985 Were improved Notice the Badge "HT-4100 High Technology" was removed in between that time period from the fender on those cadillac years.

[@markschlotter1282]

I had 2 of these and had crank break, rocker bars crack, oil loss, they are junk

[@Goldmouth020]

❤

[@sil80d]

This is the engine that had the V8-6-4 thing correct?

[@cadmanist]

You're thinking of the '81 Cadillac. Clip a single wire and it goes back to being a dead-reliable cast iron 368 like the '80 version. It was the '82-85 HT4100 that was the disaster.

[@jayson657]

No this hunk of junk was hastily rush into production to replace the failed V8-6-4.

[@yamajammer76]

Go listen to what Adam at Rare Classic Cars and Automotive History has to say about this engine. It's not good and he has a lot of experience with Cadillacs and other cars of this era. He says if you want an older Caddy avoid this engine and anything with an Oldsmobile 5.7 diesel. Both are probably the worst engines ever sold to the general public excluding the original Vega engine which was even worse. The V8-6-4 was also terrible, but if you disconnected the system and just ran it as a V8 it was fine.

[@V8Power5300]

The Olds 350 diesel can be made reliable fairly easy and is simple to work on. Headstuds and a water separator and suddenly you have a 30MPG cool highway cruiser or daily

[@yamajammer76]

@@V8Power5300 This might be correct, but as a stock design it was terrible.

[@realgone222]

Adam brought me here.

[@joshuac4772]

Did this engine, or it's variants, ever get proper aluminum heads?

[@owenhunt6796]

no

[@dwainekahicks]

Whoever Had Stock In BARS Stop Leak, Grandchildren Have Wealth

[@noscwoh1]

Such a shame. Small, light, smooth, replaceable wet liners, so much about this engine should have worked well. It was just rushed out before it was properly fettled. Too many odd mating joints, too much RTV, too much differential expansion, not enough torque in the equation. All Caddy engineers needed were another two model years of troubleshooting the design.

[@Alexs23743]

Here's something positive: Cars with this engine qualify as zero emission vehicles! (They can't emit any greenhouse gases when they're dead! ;D)

[@g2skinny]

Can you say junk I remember these things from years ago main bearing rattle every one I ever heard

[@aaronbayus3110]

This was the worst engine in the cadillacs 4.1 noted for coolant leaks if you didn't add a additive in the Radiator. The headgaskets Would leak because the block was aluminum with cast iron heads. If you've got 30000 miles out of the engine with no problems you were doing good.

[@geneo317]

This engine was underpowered and plagued with issues. This engine should have had aluminum heads. This engine was intended for the FWD models. They should have never put them in them Full size Cadillacs. I own a 1984 Coupe DeVille with this engine. It’s smooth running however with the listed problems I make sure it’s maintained.

[@6mtzhp55]

Back in school a classmate had this engine in a hand-me-down Cadillac. I remember it being pretty slow, but got slower and slower until finally it could hardly even sustain 35mph and they junked it. I can't be sure this is true but supposedly the camshaft lobes literally wore down flatter and flatter until the valves hardly lifted!? Seems like an impossible mistake after properly hardening camshafts for decades, but I've overestimated 80s GM before.

[@owenhunt6796]

i mean they still cant get it right with the ls. they have problems with camshafts aswell. I've sceen one taken out of a 2012 or 14 i cant remember which and the lifter and 3 lobes were just completely fuckered

[@JoeMama-j7s]

I gotta fever….and the only prescription is more RTV sealant.

[@TristanSpeno]

i’ve got an 84 fleetwood brougham with 140k miles on the original engine, probably the worst engine i’ve ever had to deal with

[@johnnybobgoldstein2823]

Did you have to do quite a bit of work on it?

[@sbechris]

They should have not used sealant 😂

[@brickkkkk2gr]

lol, does anybody want one of these I have a spare 😂

[@charlespierce3647]

One of the worst engines ever manufactured.

[@gsm19911]

A bean counter engine…To save money, GM should have just switched to sharing engines by then. Say a Chevy 305 that was found in a Caprice as they were slow but good engines. Better to piss off customers by not having a “true Cadillac engine” than having one of the worst engines in history ruin their reputation. They finally got smart an eventually put Chevy derived engines in their full size RWD cars. Unfortunately since 1981, there hasn’t been a good Cadillac engine the write home about. The 4.9 was OK but nothing like the small block Chevy engines. As a GM guy, Ford had it right by sharing the 302 and later the modular engine.

[@cadmanist]

Unlike the diesel debacle (which was bean counter related), the HT4100 was an expensive engine to design and produce. Tighter tolerances, new design methods, exclusive assembly line, lots of aluminum. It was engineering that dropped the ball on this one. But Cad was in a real jam at the time. The Chevy stuff is out (not-compatible with Eldo/Seville FWD). And the big B/C cars were going to be dead after MY85. They also couldn't go back to a carb, being the poster child for advanced tech and focusing on it as a market differentiator. They had just released the industry first DEFI system in '80, with onboard diagnostics, digital climate control, trip computer, and other goodies you couldn't get from Buick, Olds or the imports. Best of all, the system was both reliable and well received. The whole impetus of the decision to pull forward the 4100 was that NHTSA could not come to terms with an MPG figure on the '81 V864 system that Cad was banking on to get them to '85. That's why it only continued on in the commercial chassis which was exempt. Cad did offer the Buick 4.1 V6 (carbed) in parallel with the HT4100, but there were few takers.

[@traderdan85]

One of the worst engines of all time ..I think mainly to poor quality materials , And just plain dumb engineering . I have worked on these for decades now .. was part of a line up of losers in 1982 , the Buick v6, Olds Diesel , or the 4100 .. All instrumental in destroying the name and opening the door for the imports , now the Chinese own GM … sad

[@jayson657]

It’s just a shame Cadillac took until 1990-92 to finally put fuel injected small block Chevys in their full-sized cars. If they would have just done that in ‘82- while the other GM V8’s were still carbureted they probably wouldn’t have tarnished their reputation very much. Lincoln got away with it with the Ford 302.

[@gsm19911]

@@jayson657They did in the 1993-1996’s as well on the Fleetwoods. I had a 1993 Cadillac Fleetwood with a TBI 350 Chevy engine. The same engine you would find in a pickup. GM should have used common engines across all their brands like Ford did. The 4100 was a result of bean counters rushing engineers into coming up with this engine. Maybe if GM shared engines, they could have saved money that way and concentrated on building a reliable engine. They should have just but a Chevy 305 with the 350 as an option in all their full size cars. I had an 80’s Caprice several years ago and while gutless, it was reliable as can be.

[@geneo317]

Great video for a horrible engine.

[@MarkWG]

"Provides years of dependable service."😂😂😂😆😆😆🤣🤣🤣🤣.......... AKA........The engine that almost killed Cadillac.

[@matthewbucher8954]

Not cadillacs best engine

[@adamgutierrez8680]

Just trash engines my grandparents have a Cadillac from Simon motors.

[@johnfranklin5277]

La Quinta California.

[@jeffsmith-ze6wb]

This is one of the worst engines GM ever produced I was a mechanic at a Cadillac dealer they were nothing but trouble