Speaking of Detroit's

[junkyardjeff]

What makes those motors so prone to leaking oil,I remember them sitting at traffic lights leaving a few big puddles of oil.

[redneckrigger]

Not all Detroits leak, but so many did, they got the rep as one that marked it's territory. They CAN be made oil tight, but there are LOTS of places that they CAN leak. I had a 6V-92T in a 9500 GMC rollback that ran like crazy, but it leaked in places that I never even heard of. It was a MESSY beast. So I simply kept oil in it and ran it's heart out. Ran it into the ground and sold it to a fellow that put a rod through the block about a week later. Guess she missed me! Loved that truck, and it is only one of maybe three vehicles I have owned that I really miss. Also had a 4-71 in a 750 CFM air compressor. That old girl never leaked a drop. It was owned since new by the State of New York State Highway Dept. I got it VERY used, with about 12000 hours on it. And, it was dry as a bone on the outside, and stayed that way for about another 3000 hours, until it decided to run away one day, backwards, and made itself into tiny little pieces of Detroit. LOTS of them. BUT, I STILL love Detroits and the way they sound. Tiring on a long trip, sure, but mesmerizing none the less.

[DRIPTROIT 71]

My Dad went to school to work on Detroits, and was a Detroit mechanic for years. He always told me that he could make a Detroit "drip free."

[guitarsam326]

My Dad went to school to work on Detroits, and was a Detroit mechanic for years. He always told me that he could make a Detroit "drip free."

i wonder if its because they built up too much crankcase pressure?

[cappy625]

back in '89 I drove a international 4200 with a 318 DD/ 10spd.   hauling steel coils with it out of US steel  in fearless hills pa.   I remember the owner of the truck always telling me to keep it wound up tight and run it like your mad at it.  she would use about a gallon of oil every 4 days.  I always thought because they were 2 stroke engines that they were  just vibrating parts on the engine loose.  I also remember the air compressor leaked a lot of oil on that truck.  but  I think Sam is right a 2 stroke engine would build up a lot of crankcase pressure and that would definitely cause leaks.

[DRIPTROIT 71]

i wonder if its because they built up too much crankcase pressure?

That's what I always thought Sam, and there is probably some truth to that. Daddy always said it was because people wouldn't take the time it required to fix them. There may be some truth to both. What I do know is that in 1983 the company that my dad worked for bought over 40 new 3406 powered Freightliners, and sent the 5 remaining Detroit powered trucks to the shop in Alabama (where I think that they were treated as spares). I remember one Saturday the 1978 Cabover Ford pulled on to the yard to the fuel pump for fuel. The driver got out, opened the side box, pulled out a gallon of oil and started pouring it in the access on the front. Someone had lost the oil cap, (driver said it was because it was off more than on) and according to the driver no one else would drive that truck. The funny thing is, when it left Lexington it was probably the best of the 5. I said all of that to say this: I think Detroit 2 strokes much like steam engines have a lot of character, but also require a little more constant maintenance (as a general rule) than say a Cat or Cummins did.. Keep in mind most of my experience with Detroits was helping my Dad. My personal experience was mostly with Mack and Cat. So my observation may not be 100% accurate. But,I do love the sound the 2 stroke Detroit makes though. I road many a mile listening to one hum. That makes them my favorite old diesel.  I would like to put a 4-71 on my M Farmall one day.

[Aaronw]

The first engine I was assigned to was a 1971 Duplex / Van Pelt with an 8V71T under the cowl. That truck was 22 years old when I started driving it, but I don't remember any issues with leaking oil, it was no worse the 1976 Mack CF600 or 1970 Ford C800 it shared a station with (volunteer department so everything we had was second hand).

The inline 71s came out in the 1930s and the v71s came along in the 50s, both types sold well into the 90s so obviously Detroit Diesel did something right when they built these. Perhaps the reputation came about because they would keep going even if poorly maintained? Not so much that they had to leak oil, more that they would run while leaking oil from every joint and seal. Just a thought, I can't see an engine that leaked oil like a sieve as "normal" staying in production for almost 60 years.

 

I'm with Driptroit, there are other good diesels, but nothing sounds like a Detroit 2 stroke. I grew up riding GM New Look buses most of which were running some form of Detroit. Just hearing that sound takes me back.

 

I wish I had room for one of these, mobile hobby room.

[redneckrigger]

The Detroits that I had all had crankcase vents that worked well. Built up pressure was not a problem, from what I have been told by a friend who still turns wrenches on a few of them. But, compressors, alternators, crossover tubes, o-rings, and about every other place that could leak did. We had a 1971 Seagrave/FWD pumper in our fire department. We bought it second hand with an 8V71 in it. That truck ran super and didn't leak anything at ALL like my 6V92T. But it took a special type of driving to get the best out of it. The problem was the other four trucks we had were 2 Cummins 250's, a Mack ENDT 673 and a gas Waukesha 817 C.I. in a Thibault/FWD. None of them needed to be run as if you were mad at them as did the Detroit. The Seagrave eventually died a slow death because no one drove it correctly. You CAN'T drive 'em like a Cat or Cummins, or even a Mack. 'Twas a pity, as the was a sweet machine!

[junkyardjeff]

There is another two stroke diesel that sounds just like a Detroit but its a British motor,its a opposed motor but not like you would think and would be hard to describe but I would like to have one in a mid 50s Commer cabover.

[guitarsam326]

Ive never had the privilege of working on or driving an old Detroit, but i have been told that if you lugg it, you can blow it up. As far as the crankcase pressure, it all comes down to who services it, if it gets clogged, it wont work, and it will find a way out elsewhere.

Edited December 31, 2015 by guitarsam326

[Force]

Yes the two-stroke diesels has a distinct sound, it's hard to tell them appart from the sound and I have difficulties hearing if it's a 6-71 8V-71 or 92, or 12V-71, they all sound very similar to me.

Edited January 1, 2016 by Force

[redneckrigger]

They are ALL music to the ears!

[gino]

They are ALL music to the ears!

yup they sure are !  I remember riding with my dad in his freightliner screaming up I95.  people used to roll  their windows up in cars when we passed them.

I used to get a big kick out of it. my dad always told me : keep your foot right into it, they love it !

Edited January 1, 2016 by gino
can't spell today