detroit diesel

Covers engines and transmissions
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demingboy
Posts: 7
Joined: Thu Dec 15, 2022 11:01 am

detroit diesel

Post by demingboy »

Does anybody in this group have a detroit diesel in their RV? And if so how is it doing?
wolfe10
Posts: 176
Joined: Sun Oct 27, 2019 4:12 pm

Re: detroit diesel

Post by wolfe10 »

Probably need to ask about a specific Detroit Diesel series.

A 4 stroke 8.2 liter is very different from one of the 2 stroke DD's or a 60 series DD.
Brett and Dianne Wolfe
Ex: 2003 Alpine 38'. Ex 1997 Safari Sahara. Ex 1993 Foretravel U240
Moderator, FMCA Forums 2009-2020
Chairman, FMCA Technical Advisory Committee 2011- 2020
Moderator, http://www.dieselrvclub.org/ (FMCA chapter) 2002-
demingboy
Posts: 7
Joined: Thu Dec 15, 2022 11:01 am

Re: detroit diesel

Post by demingboy »

omg I guess you are correct about which engine not specified. I had thought the 2 stroke was never used in Safari. Yes it is the 8.2 Detroit
Joeoren
Posts: 23
Joined: Wed Nov 11, 2020 6:08 am

Re: detroit diesel

Post by Joeoren »

which 8.2 do you have what horsepower rating is it?
1990 safari serengeti High Tech editon 8.2T Detroit AT545
2009 Subaru outback xt - Toad 1
1999 mazda miata - Toad 2
wolfe10
Posts: 176
Joined: Sun Oct 27, 2019 4:12 pm

Re: detroit diesel

Post by wolfe10 »

210 was the standard HP of the DD 8.2 four stroke.
Brett and Dianne Wolfe
Ex: 2003 Alpine 38'. Ex 1997 Safari Sahara. Ex 1993 Foretravel U240
Moderator, FMCA Forums 2009-2020
Chairman, FMCA Technical Advisory Committee 2011- 2020
Moderator, http://www.dieselrvclub.org/ (FMCA chapter) 2002-
Joeoren
Posts: 23
Joined: Wed Nov 11, 2020 6:08 am

Re: detroit diesel

Post by Joeoren »

Mine came with 225hp just was wondering if he has the same as me since mines an oddball that was actually a marine engine fitted with a non truck water pump and uses a couple different unavailable parts such as special valve covers. I have only seen 1 other safari 8.2 chassis was in a junk yard and the engine in that one was way different than mine I believe it was a nonturbo variant which was really strange.

I have access to a detroit database with all part numbers etc if you want to provide your engine serial.
1990 safari serengeti High Tech editon 8.2T Detroit AT545
2009 Subaru outback xt - Toad 1
1999 mazda miata - Toad 2
Joeoren
Posts: 23
Joined: Wed Nov 11, 2020 6:08 am

Re: detroit diesel

Post by Joeoren »

Forgot to add: don't believe the nonsense on this engine most is just because mechanics don't like anything not standard and this 4 cycle engine in the 80s was not standard
and needed alot of specialty tooling. Did a 10k mile trip in 2021 and had literally zero issues with my 8.2. Warning at this point of life in your 8.2 this is basically an engine you will most likely need to work on yourself because most mechanics won't. I consider myself the warranty at this point.

I do oil change every 4k. Use high quality oil such as rotella t6. All filters at oil change.
Every other full tank of diesel - Stanadyne Performance Formula Diesel Injector Cleaner - 32 oz Jug - 43566.
I'm no snake oil expert but this stuff has consistently made the engine run better and better.

You will struggle pulling a vehicle on steep grades just remember how fast you make it up is the max you want to go down. You should have an at545 like me meaning this transmission will NOT save you so be very safe and not mess around.

At545 I used transynd and let me tell you it shifts buttery smooth now my wife said first time in it after the fluid change did you replace the transmission or something? Without me mentioning I did it.

I have recently just deleted my muffler and have it straight out the side, honestly it's not much louder and I have not tested driving yet but it sure seems like the turbo is a lot less restricted plus my 30 year old 30k mile muffler was completely caked/clogged. I will be taking a trip through the mountains in next couple weeks I'll let you know if the effort is worth it.
I pull an 09 subaru outback.
1990 safari serengeti High Tech editon 8.2T Detroit AT545
2009 Subaru outback xt - Toad 1
1999 mazda miata - Toad 2
demingboy
Posts: 7
Joined: Thu Dec 15, 2022 11:01 am

Re: detroit diesel

Post by demingboy »

Hi there
Thank you very much. Will follow all your recommendations. Makes sense to me. I have noticed the no back pressure on downhill for sure.
Thank you for info
Joeoren
Posts: 23
Joined: Wed Nov 11, 2020 6:08 am

Re: detroit diesel

Post by Joeoren »

heres a reply when i first got my rv from a BIG name in the used school bus community that has bought and sold thousands of school buses and much experience in 8.2 detroits.

its a bit of a read some information may not be relavent but may help other safari 8.2t owners understand their driveline better:


The 8.2T was a good engine, but most people on the internet hate it. Of course, most people on the internet have never owned one, have never been around one, and never will be.

First of all, I am surprised to hear that you have an AT545. Every 215 hp or larger 8.2L that I have ever had was attached to an MT643. The difference, when driving them, is that the AT545 has some slippage in the torque converter, whereas the MT should (and they even sometimes work) lock up the torque converter. While running down the road, if you let up on the throttle, does the engine lose any rpms while the bus is still traveling the same speed? If it loses maybe 300 or 400 rpms, at the most, it probably has an AT545. If it doesn't lose any rpms when you let up on the throttle, it has a locking torque converter and an MT643. If it drops almost to idle when you let u on the throttle (free wheeling as if you pushed in the clutch on a stick shift), you have an MT643 with a defective torque converter. This is, by far, the most common way these old Detroits went down the road. Again, the internet hates the AT545, but loves the MT643. In reality, we worked on an AT545 very rarely. In 49 years, I believe we have lost 2. There was a 3rd one years ago that lost reverse, but it was actually an AT540 hooked to a 4000 rpm gasoline engine. About half of the MTs we ever saw had defective torque converters. Just last month, I had two different people stop in with their skoolie conversions, complaining about their AT545 free-wheeling and giving them no engine braking. In both cases, they had MT643s.

If the torque converter is failing, it takes a lot of rpms to move the bus. If you are running a steady 2900 rpms at 70 mph, and the rpms do not vary as long as you are maintaining 70 mph, then you have an MT643 with the torque converter working properly. A 545 would have about 10% slippage. You would sneak up to 73 mph or so going down a hill, and drop down to 66 mph or so before dropping rpms. What is the GVWR of your motorhome chassis??

It doesn't matter if you have an MT643 or an AT545. They are, both, basically the same transmission to keep serviced. The AT545 holds 28 quarts of oil. The MT643 only holds 18 quarts. The AT torque converter slippage creates heat, so the engineers compensated for it by adding 10 quarts of fluid. If you have an MT that the torque converter is not locking up, you are creating heat like there is no tomorrow. With either transmission, I would want a temperature gauge so I could see how it was doing. IF you do not have one, I would suggest getting one. That way, when your transmission is not happy, it can tell you.

Are you running Dexron III transmission fluid? If so, you should be changing it every year. There is an internal filter (screen) inside the pan that should be changed every year, as well. If the fluid ever reaches 300 degrees, you should change it as soon as possible. It has cooked out all of it's protective additives. You also have a spin-on filter in the line running to the radiator from the transmission. I change this every six months on my own vehicles. Allison said to do it annually. As this filter gets dirty, fluid flow is reduced. This means less fluid is getting to the radiator to be cooled. You need a good volume of fluid passing through the radiator in order to keep the transmission cool.

You can switch over to an Allison approved TAS-295 transmission fluid. With this, your transmission will run much cooler. Allison claims you can run it for years. Some schools have made the switch in their 545s and never changed the fluid ever again. They just change the spin-on filter once a year. Castrol Transynd is what comes in new Allison automatics. Very few transmission fluids say "Allison approved". You should find one that says it, if you make the switch to synthetic fluid. If you have a temperature gauge, you will see how much cooler the transmission runs on this newer fluid. Approved Fluids (allisontransmission.com)

The 8.2T has horsepower rated at 3050 rpms. These engines, because they are V8s, they need to be revved up high to produce their horsepower. Their torque was rated at 1,700 rpms. Unfortunately, if you lugged them at the 1700 rpm mark for extended periods, they would lose a head gasket. They really wanted to be revved up all the time.

With only a 4 speed transmission, there is a big gap between full engine speed and dropping a gear. Keeping the engine at a lower rpm in order to run a slower speed greatly increases fuel economy, but also drove the heat deeper into the engine and broke down the motor oil much quicker. Today, you can run synthetic oil with a CK-4 rating that greatly reduces the engine temperature and increases the life expectancy of the oil. We used to run 15w40 Shell Rotella T or Chevron Delo for 3000 miles in those engines. With the new synthetic oil, we run them 5000 miles with 15w40 Shell Rotella T6 synthetic. These old engines are dirty, not like the newer engines with much tighter tolerances. We don't run 5w40 oil in these older engines, but do in the newer models. For us, engines built after 2003 were designed to run much higher temperatures. Your engine was built with a feeler gauge. Modern engines are measured by laser beams. Tolerances are far tighter on modern engines. The new Detroit Diesel school bus engines, DD5 4 cylinder and DD8 6 cylinder, can run 45,000 miles on an oil change. In highway use, they can run 60,000 miles. BUT, they require 5w40 CK-4 oil.

To keep your engine happy, it not only needs good oil and filters, it also needs good coolant. You do not want coolant additives in these engines. Additives settle out, clog radiators, and also coat water jackets, making heat transfer less efficient from the block to the coolant. Modern engines need additives, and each engine has it's own chemistry. These old 8.2s liked regular old green coolant, 50/50 with distilled water. The system should be flushed every couple of years, and refill with coolant that is NOT charged... and add nothing for diesel cooling system treatment. You do not have wet sleeves, liner pitting issues, or any of the problems that modern diesel engines have. Use old fashioned green antifreeze.

I very much prefer a fail-safe thermostat. In the event the thermostat overheats, it opens up and remains open. You get full fluid flow to the radiator. A standard thermostat can stick shut, overheat, and still not open up. Fail-safe units are far safer, and the older an engine gets, the more likely it is to overheat. Overheating these engines is the most common way to destroy them. Very few engines ever wore out. They almost always got overheated and destroyed. Keeping the engine revved up also increases oil and coolant flow, which means a cooler engine. A cooler engine is a happier engine, with this engine. Run 180 degree thermostats.

The turbocharged 8.2 is different from the naturally aspirated version. The 8.2N has domed pistons and a much higher compression. They fire up a bit faster on a cold morning and burn less fuel. The 8.2T has a dished piston. This enlarges the combustion chamber so it can swallow more air from the turbo. With more air, they can put in more fuel to make more power. The low powered engines were true fuel pinchers. The 225 hp 82T was not very good on fuel. It didn't make a whole bunch more torque, but it have more horsepower. Because of the larger combustion chamber, the 8.2T wasn't quite a quick to fire up on a cold morning, and it made more smoke while cold.

The injectors were never much trouble on these engines, but they were made prior to biodiesel. Today, you have biomass in the fuel at many gas stations, and nearly all truck stops. Vegetable oil gums things up real bad. As injectors start to clog, they become less efficient and fire late. This retarded timing produces less "ping", more smoke, and considerably less power. Plus, the injector tips get clogged, so they spray less fuel. In fact, they often stop spraying a nice pattern and begin to drip fuel into the engine. There are all sorts of injector cleaners out there, but not all of them work on mechanical injectors. When your engine was made, diesel fuel had plenty of sulfur and actually felt like oil, if you got some on your hands. Today's ultra low sulfur diesel fuel actually dries out your hand, if you get some on your hand.

Injector pumps also suffer from vegetable oil in the diesel fuel. Deposits build up that reduce the ability of the pump to produce the high pressures necessary to pop off the injectors. Quality biodiesel can add lubricity to the fuel, but it cannot get rid of the deposits that form inside your system. Cold weather performance is worse when vegetable oil is added, as well. On the fuel pump, it will tell you if "biomass" is in the fuel. B5 is 5% vegetable oil. B20 is 20%. Nearly all truck stops run biodiesel. We try to never buy fuel from truck stops. We stop at gas stations. If they have biodiesel, we move on to the next station. Not only does the engine suffer, but so does your wallet. Fuel mileage is reduced (they claim) about 5% when vegetable oil is added. We keep super good records of fuel consumption, since we have to pay road taxes in all states through which we travel. We see more like a 15% drop in economy when we run biodiesel.

Are you using good quality filters? I always prefer to use Allison filters in Allison transmissions and Detroit Diesel filters in Detroit Diesels. For us, this isn't always easy. So, we end up using more Wix and NAPA Gold filters. We try to avoid store brand filter, Baldwin filters, and other brands that are not high quality. Fleetguard filters from Cummins are good filters. Keeping clean filters on your engine and transmission will keep it happy. If you use poor quality lubricants and poor quality filters, your engine and transmission will suffer. With CK-4 oil, Wix filters, and Transynd transmission fluid, your engine and transmission should remain happy for many years.

As for the rpms and speed, slowing down is hard on this engine. It likes to crank up fast. If you slow it down, you will shorten it's life. Adding a 2 speed rear axle so you can split gears isn't a bad idea, but it isn't cheap. It is nice to be able to go fast, but with this engine, it makes it difficult to justify going slower. These engines are governed at 3050 rpms. If your tach is reading 2900, it might be off a little bit. You definitely never want to get this engine under 1700 rpms. When these engines were accompanied with stick shift transmissions, the drivers often dropped below 1700 rpms. This caused head gaskets to blow out. By design, the head can move on top of the block. Lugging the engine causes the head to move. It literally wears out the head gasket. Keep it cranked up!!

In boats, these engines were not good at all. They couldn't run slow without damage. At higher rpms (I've been on boats where they were cranking this engine at 3900 rpms), the bottom end was not real strong. They had a lot of bottom end failures. I sold a bus to a woman, once, who drove her 8.2 through the Pennsylvania mountains. At the bottom of one mountain, she lost all power and began smoking real bad. She barely made it up the next mountain before the engine shut down, completely. When the shop tore down the engine, every rod in the engine was bent. The crankshaft was blue from heat. Her bus was geared for 57 mph. She said she got it up to 72 doing down the mountain. We did the math and determined the engine reached 4100 rpms. It was destroyed.

Many people call these "throw away" engines. Most people interpret that as meaning they are not rebuildable. This is not true. It just means you have to pull it out of the chassis before rebuilding it. These engines have steel sleeves pressed into a cast iron block. As long as the block is not damaged (this is true with any engine), these engines can be completely rebuilt back to original specs. I used to put the sleeves (also called liners, cylinder walls, etc.) in the freezer the night before installing them. Then, they would drop right into the block without needing to press them in. I used to get quite a few buses with this engine that had overheated. I could fix them by rebuilding the heads, planing the block, and dropping in new sleeves. It cost me about $2000 back then. Today, I'm guessing it would be twice that.

You could always lower the rear end gear so the RV only went 62 mph. Then, the engine would be in the high rpm range more, the fuel mileage would be better, but the trip would be longer. The engine and transmission would be happier, but you might not be.

Oils have improved, greatly, since your engine was built. Transmission fluids have improved, greatly, since your transmission was built. Rear end grease is not much different. Coolants have changed, tremendously, but your engine needs the old fashioned, green, ethylene glycol antifreeze. Have you flushed the radiator? Do you have a coolant filter? I would want to flush the system, add fresh coolant, and replace the thermostats with fail-safe models. There are two thermostats. If one fails, the other one usually works fine... but you don't really know if one has failed. Is this a rear engine chassis? If so, I think I would run 165 degree thermostats to increase the flow to the radiator. Do you have two overflow tanks? Some of these came with one, but kept blowing coolant out under heavy loads. Then, Detroit wanted a second one to catch what got blowing out of the first one.

A few models (I recently had one in a fire truck) had 2 oil filters. They were the same filter... times two. I am guessing you have just one filter, but you might have two. When you change the oil, have you sent in an oil sample? This is good for measuring engine wear. Each bearing, for instance, is made of layers. Each layer is a different alloy. If they find certain alloys in the oil, they know how far the bearings have worn. Every part is a different alloy. By analyzing the oil, they can determine how much wear the engine has. Also, they can tell you if any antifreeze is getting into the oil. The radiator cooler can leak and mix coolant into the transmission. (total destruction of the transmission if this occurs.) The oil cooler can leak and put oil into the coolant. A head gasket can fail and put coolant into the motor oil. It is never a bad idea to run oil samples. You local NAPA store can probably do it for you. I would definitely run CK-4 15w40 oil in that engine, today. You can leave it in there a year, if you don't put 5000 miles a year on it. I have it in a Mercedes engine and keep it two years... after sending in oil samples for a few years to make sure I wasn't doing it any harm.

Do you have a temperature gauge on the transmission? If you have an added transmission cooler, that isn't bad. Running 70 mph and putting 225 hp into the transmission will create a lot of heat. The AT545 can handle up to 235 hp and 445 lb ft of torque. The 215 hp 8.2T in my fire truck produces 495 lb ft of torque and has an MT643.

What brand of chassis do you have? The 8.2 was used by quite a few different manufacturers. GMC/Chevrolet and Ford were the most common, but I've seen it in many others. Have you ever heard of an Asia-Smith chassis? I had plenty of those with 8.2s. Is yours a front engine? Or rear engine? In school buses, every manufacturer offered an 8.2. Bluebird put them in some All Americans. Thomas put them in front and rear engine MVP buses. Wayne built some front engine transit buses with it. Superior built quite a few buses with the 8.2. Carpenter had many 8.2s in their front and rear engine flat nose buses. Even Ward used them in some of their President models.

V8 engines need to be revved to make power. Inline six cylinder engines do not. You have 500 cu inches working for you, but only 2 cylinders at a time are actually producing power, because of a 90 degree big block V8, 4 stroke engine. So, you have 125 cu in working for you at any given moment. The new DD8 inline six is 470 cu in. Maximum horsepower is rated at 2200 rpms, and it can turn up to 2550 rpms. A 250 hp model has 660 lb ft of torque at 1300 rpms. This is significantly more power than your V8. A 4 stroke six cylinder, by design, has 2 cylinders working for you at any given moment. This is 156.6 cu in working for you at any given moment. This is why every semi truck has a six cylinder engine!
1990 safari serengeti High Tech editon 8.2T Detroit AT545
2009 Subaru outback xt - Toad 1
1999 mazda miata - Toad 2
demingboy
Posts: 7
Joined: Thu Dec 15, 2022 11:01 am

Re: detroit diesel

Post by demingboy »

Wow. That was allot of information Very nice of you to take the time to do that.
I have a 1990 Safari class A. Pusher on an oskosh chassis. Built like a cement mixer I swear. It has all gauges for temps, engine and transmission. They seem to follow each other pretty closely. Engine gets warmer so does transmission.
All the RPM you mentioned is about what I do. It seems like the transmission (allison) 4 speed holds a little bit on downhill but I definitely have to use brakes on steep slope. It does help to drop to lower gear and then I do watch rpm. and brake as needed.
It does have older trans fluid in it. Has I believe two engine oil filters and is the turbo model. Does not seem to help much but it must work.
I think I will do the oil check. Meant to do it last year and did not. Guess I better do that.
Will darn sure change and flush or clean radiator. Cant believe a 32 year old radiator does not leak but lucky I guess.
Trans fluid change on the list also.
I have had the RV about 8 years and have been from Coast to coast. Kinda like keeping the girl running as it still looks nice.
Your reply greatly restores my confidence in the Detroit engine.
One of the few positive comments I have ever read about it. And I have read them all lol.
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