Rebuilding a Detroit Diesel blower from a 6N71 engine.

[@robertbowman3406]

Kindly correct me if I am wrong. There should be .003 play in between the rotors where that little tip sticks out from each rotor. I learned that when I was stationed in Germany 1961-64 with the U.S. Army. The sight of a brand new 6-71 blower is a sight to behold. They are beautiful. And if I am correct the blower rotors turn 1.1 turns for every turn of the crankshaft. They howl when they run at 1800 rpms. We had the 4-71s installed in the Huber-Warco grader which we worked on.

[@brunogervais7632]

Yes great job, there is longtime I could know how is inside the blower. Now I know thank.

[@stevenfoust1979]

Loved video, if you ever convert one of these blowers over to gas I would really like to see that one done. Thanks for the great video. Steve

[@firstname6208]

I witnesses an old timer set the c and cc clearances in a few minutes. tap the drive gears on far enough so they are straight. start measuring the clearances, first tapping one gear down then the other until you get the desired clearance. now measure with a depth mic from one gear to the other. that is exactly the difference in shims you need to install.. only need to pull the gears off one time. EH! btw, that ol' timer worked in a ddc rebuild shop. he could rebuild 8 blowers per day. those blower rebuild tools looked like it has been 40 years since they have seen the light of day. good stuff.

[@dykemamechanical]

I only do a handful a year now. not many 2 strokers around anymore.

[@ejdprice]

I'm not really following you as to where to measure with the depth mic. Are you comparing gear teeth comparison of which one is sticking up more than the other, once the C / CC clearance has been achieved? .......... I've never considered the gears as being perfectly the same thicknesses when manufactured to one another to begin with, but maybe they are?

[@JeffinTD]

Nice. Becoming a lost art I’m sure.

[@carytowncat]

Bad ass! A thing of beauty!

[@TheMatrixgod]

hi can you help me,recently my 692 detroit started to warm up at 1200 rpms,i had a mechanic do the injectors where it didnt do munch,next we opened the blower and turbo,he said the turbo looks like needs replacing but the blower rotors are moving when the engine is off they are moving like a quarter inch not the long way the long way is tight but side to side its moving quarter inch ,is that ok and also maybe you can rebuild this one as i watch your video and wow like that is very good workmanship,thanks

[@мишамишин-ч5у]

thank you !

[@GOLDENHALK37]

Wow great work I need to do the same thing I have a GM 4905 with an 8 v 71 leaking all out of the bottom of my blow a gasket on the intake

[@dykemamechanical]

arthur cofield remember it takes special driver tools to do this job! it is not a diy job, for the most part!

[@kevinhornbuckle]

Arthur, did you figure out where the oil was leaking from?

[@JoseRivera-mo9gz]

last end plate is in correct posision.

[@marlborodemoura1377]

Quantos hp e torque? ?

[@olsenbaliktad1569]

Hello boss, is there any specific liquid material to use for cleaning blower?

[@dykemamechanical]

olsen baliktad no. whatever you chose to use to clean aluminum....

[@luismanueltemixmarquez5380]

hello goodnight friend a question like I can get the key alex screw GMC 671 blower naturally (without turbo) that moves the water pump, you would have some video or something to support me greetings from mexico

[@dykemamechanical]

I am guessing that would have to come from a Detroit Diesel dealer, sorry.

[@Swerve61]

Luis Manuel Temix Marquez

[@willdiesel3909]

El soplador,tipo lobulo helicoidal.Interesante.

[@ThePaulv12]

Doesn't N mean for Naturally aspirated?

[@dykemamechanical]

no. 'N' means 'inline', vs 'V' is a V style, like a 6v71 is a v6, or 8v71 is a v8. 6n71 is 6 cylinders in a row, 71 cu in per cylinder. Hope that helps!

[@dykemamechanical]

there was a TTA engine that was not twin turbos, but some special fuel squeezer thing that didn't work well once. But you are correct.

[@rickmcbride2980]

N does stand for naturally aspirated the engine would be called 6 l 71 n six cylinders in line configuration 71 series naturally aspirated

[@TriniRogue]

i didnt think that these blowers did more than push air through a detroit diesel, hearing that people used em to hotrod sbc is interesting, how much psi do these push?

[@dykemamechanical]

+TriniRogue that depends on how fast you spin it and what kind of fuel you are going to burn.

[@TriniRogue]

Rob D thats a good point, always thought blowers had one set psi based on the belt gear size regardless of engine etc

[@dykemamechanical]

+TriniRogue even camshaft profile can make a difference in boost. we had a 8v71 making 40psi in the air box once. it ran pretty good.... for a while.....

[@kevinhornbuckle]

This is why upgrading a naturally aspirated Detroit to a turbo involves changing the cam shaft.

[@krillin63]

Detroits don't naturally aspirate... thats why the blower.

[@mackohernandez9573]

Did you use a petruleum base liquid to clean all those parts?

[@dykemamechanical]

No, hot water & detergent.

[@gregstone6374]

Come on. Show timing the rotors and checking clearances and how many times you have to pull the gears and change shim thickness to get it right.

[@dykemamechanical]

Greg Stone you mean the easy stuff.....

[@pietrorizzo8627]

the seal down 2-3 millimeter respect to face ??

[@dykemamechanical]

I don't know the dimension as it is done with the seal driver. but it has to be deep enough the seal lips don't drag on the rotor and down fall off the wears leave on the other side.

[@pietrorizzo8627]

@@dykemamechanical ok tank's, another questions please, the teflon seal that you used is for turbo engine or not ?

[@dykemamechanical]

I don't think there is a difference. This was a non turbo, but the seals I have been using look the same for turbo engines...

[@dakotareeves5007]

where do you usually get your new bearings and seals from?

[@dykemamechanical]

look up ASC Warehouse

[@kevinhornbuckle]

Very nice work. Did it take the same number of shims going back together?

[@dykemamechanical]

I don't remember but they usually do if they were assembled correctly before.

[@nottypinoy]

Hi Rob, direct email address? I went to the link but did not see any parts for the 71 series. I need to rebuild 2 blowers for my 6-71's. They appear to dumping oils slowly into the airbox. I have many questions regarding this process. One engine was a 671 T but I want to verify the blower, if it is the same as a non T 671. As I recall a dealer (Pacific Power Products) told me that the T engine has a different gearing for more air?? Also, is there a way to install the seals without the special tools? Any info you can provide would be greatly appreciated. Salamat, Jonathan

[@dykemamechanical]

just call them. they have parts. Thats where I most of my two stroke parts. As for oil in the air boxes, it is usually from rings not blower seals. So inspect your blower before you condemn it. there is no gearing in a blower other that to turn both rotors the same speed. Any actual speed change would be in the drive gear on the rear gear terrain. You could have seal tools made if you know someone with a lathe.

[@dykemamechanical]

I will get you a drawing for the seal driver

[@nottypinoy]

disregard.I just used a socket and drove it to the depth described in the DD manual.

[@thevacuumtubejunky9774]

I have a question. I hear both positive and negative results regarding turbocharged Detroit's. Will a turbo increase or decrease the fuel efficiency when applied to these engines in a bus or truck application? Thanks for sharing your video, your work looks awesome. Kind regards Eric Dee

[@dykemamechanical]

A turbo will increase efficiency only if you don’t add more fuel to make more power. Any time your engine is making black smoke you are wasting fuel. A turbo will add more air to allow better, more complete combustion reducing waste in black smoke, making more power, doing more work

[@thevacuumtubejunky9774]

@@dykemamechanical thank you for your reply. That makes sense, I have heard a lot of the opposite from many searches, but as you stated in a nutshell, if your not adding more fuel, than the only thing left to do is gain power out of what fuel was initially added. Thanks for sharing your video and knowledge. Kind regards Eric Dee

[@firstname6208]

on these 2 cycle Detroit's the turbo can only do so much before the supercharger gets in the way of the turbo boost. Detroit changed the endplates on the turbo versions to allow boost to go around the end of the roots via a special BYPASS port. not sure the model but the silver 92"s had them for sure. I drove an old 9500 we converted from 318 to 350 with big injectors and a turbo. that old girl would really roll if you kept the rpms near the top all day long. she would sing the song.

[@firstname6208]

@Mr Sunshines not sure how much advanced a person has to get but I worked on Detroit's for 43 years including 238 and 318 and 350's, 92's, series 60 of which I personally overhauled HUNDREDS, and the new DD engines after having SCHOOLING AT THE DDC TRAINING CENTER. did I quote anything incorrect in the above paragraph? possibly YOU did not interpret correctly what I was communicating. a supercharger is a device that mechanically driven moves air, either roots, screw or turbine vanes. in the early days of drag racing they took superchargers off Detroit's and put them on hemi engines to BOOST air into the engines.

[@ThePaulv12]

@@firstname6208 Yeah they saved 30hp those bypass blowers.

[@ryotaryuu]

pictures?

[@JoseRivera-mo9gz]

I fixed many of that one.

[@JoseRivera-mo9gz]

The tools for the seals and sleeve are obsolete. you need is the correct.

[@nottypinoy]

Any idea where I can get the tools and or buy a rebuilt 6n71 blower?

[@dykemamechanical]

look up Asc Warehouse... here is the link www.dieselenginepartsandcomponents.com/

[@ThatRandomMan1]

You forgot to fill it with oil and oil the bearing lmao that supercharger won't last long

[@dykemamechanical]

oil will not stay in the blower, it is pressure fed from oil pump. it is up to installer to pre-lube before install.

[@ThatRandomMan1]

@Mr Sunshines have you ever heard of prelube? Prelubing bearings? Whoa WHAT DOES THAT MEAN!? I know 😂 dumbasses on youtube

[@briananderson3801]

Yea and if you don't time the timing marks right it will turn about 30 times then blow all to prices I know this from sperience. Lol

[@lobmin]

Lol what a bummer

[@hebmacman3788]

Sorry but I believe the "N" designator stands for "Naturally (Aspirated)"... I know, you're now thinking how can a supercharged engine be considered naturally aspirated... But, remember, this is a 2 stroke engine... 2 stroke engines are either aspirated by crankcase pressure (common in small 2 strokes) or by a blower/turbo... In these cases the function of the blower/turbo isn't as much to push more air into the cylinder (so as to allow more fuel) but rather to provide sufficient scavenging and charge air... In fact, ALL Detroit Diesel 2 strokes are equipped with a blower... Without the blower/turbo these engines would barely function... Some Detroit Diesels have a turbo (or two or more) in addition to the blower... The function of those IS to allow more air (so that more fuel can be burned)...

[@ThePaulv12]

Yeah I asked that. The turbo blowers have a bypass flap to reduce blower pumping losses and are different to the naturally aspirated blowers. No doubt some moron will read this and tell us we're both wrong and that they pump .5psi-1psi and are therefore a supercharger ignorant of the fact they take 100hp to drive and are a direct pumping loss on the motor causing high specific fuel consumption contributing to their demise in mainstream automotive use - but still what would we know? ...

[@ThePaulv12]

@super pickle Where did I say N stood for inline? Yep it is possible you're correct N stands for what you say it does. I can't be bothered arguing. [send abuse]

[@ThePaulv12]

@super pickle No probs. It happens on phones. Of course I'm an angel and nothing like this has ever happened to me ... - One time when I had ~150 tabs opened on my computer in about 11 instances of Firefox I posted a reply in the wrong vid comment and when I realized I tried to explain my error which only made it worse because it looked like I was backtracking which I wasn't because I got cross and opened the wrong tab trying to hammer out a quick response. Oh dear! Anyhow, all's good : ) Cheers man!

[@robinsontovar3207]

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