Engine options for the 1990 Thomas Saf-T-Liner

[IDoMy0wnRacing]

Good day ALL,

I am struggling to find an answer.

I have a 1990 Thomas Saf-T-Liner WestcoastER pusher with a Cat 3208, and an Alison MT643 transmission.

My question is, what other engines will fit in this vehicle, or what other engines were available for the 1990 Thomas pusher, Schools buses?

According to my oil sample, I have coolant in my oil. The Cat 3208 isn't considered a rebuildable engine, disposable so to speak, when it goes bad you just replace it with another one.

If I have to replace the Cat 3208, I don't want to replace it with another Cat 3208.

I'm just not sure what engines are available that I will fit without too much modifications and bolt-up to my Allison Transmission and keep going. If that makes any sense?

I am sure that the Cat 3208 wasn't the only engine option available for the 1990 Thomas Saf-T-Liner School Buses at the time.


Thanks ALL,

Ed

 

[s2mikon]

Do you want to stay all mechanical? 8.3 Cummins, IH DT series come to mind. You are looking at a lot of work. It may just need head gaskets.

 

[Hooker-SKO]

You can pretty much put any engine you want in it as far as the medium duty diesel engines. Cummins, Cat's, Mercedez not even worth mentioning. It's all a matter of getting the right engine moutns or using the correct mounting holes to what is there. The bus is probably punched with holes in the frame for all of the above. These are usually pretty much universal frames so to speak. IMO, or where my own personal struggle would come in, is the wiring and any computer work that would need done. s2m above mentions go all mechanical, and that would sure make things easier, but you're likely to have some kind of a computer anyway to get any kind of good transmission combo that has OD and lock up converter. My biggest concern would be to avoid all the emissions you possibly could. You have a good bus, being a rear engine flat nose, so the 8,3 Cummins would be a fantastic option and my first choice also, but I'd want at least an Allison 2000 or 2500PTS, and some will disagree but my first choice for transmission, and I thnk you should too since it's rear engine, that's a looooonng way for a shifter cable, so I'd go with the MD3060 electronic Allison with the electronic shift pad controller. That shift pad also allows you to pull transmission codes. So try to find you an 8.3 Cummins with an Allison MD3060. Make that your goal but if you have to settle or consider something else, come back and ask for opinions. Maybe you can find a complete rusted out bus, wrecked or burnt bus that'll never see the road again, but has the complete powertrain in it. IIRC, you can even get engine and transmissions out of dog nose front engine buses, since your rear axle gears are going to be reverse cut which is why the bus runs forward with the engine and trans behind the rear axle. I do believe that part takes care of itself.

 

[IDoMy0wnRacing]

Do you want to stay all mechanical? 8.3 Cummins, IH DT series come to mind. You are looking at a lot of work. It may just need head gaskets.

I would love to stay all mechanical. My two Gilligs are Cummins 855s. Cummins is my first choice.

Head gaskets could be done, but the engine might not be worth the effort.

The Cat 3208 is a consumable engine. The sleeves can't be replaced (because it isn't a sleeved engine), so no real in-frame rebuild.

If the 8.3 will fit, that is what I am going to look for.
Thank you.

You can pretty much put any engine you want in it as far as the medium duty diesel engines. Cummins, Cat's, Mercedez not even worth mentioning. It's all a matter of getting the right engine moutns or using the correct mounting holes to what is there. The bus is probably punched with holes in the frame for all of the above. These are usually pretty much universal frames so to speak. IMO, or where my own personal struggle would come in, is the wiring and any computer work that would need done. s2m above mentions go all mechanical, and that would sure make things easier, but you're likely to have some kind of a computer anyway to get any kind of good transmission combo that has OD and lock up converter. My biggest concern would be to avoid all the emissions you possibly could. You have a good bus, being a rear engine flat nose, so the 8,3 Cummins would be a fantastic option and my first choice also, but I'd want at least an Allison 2000 or 2500PTS, and some will disagree but my first choice for transmission, and I thnk you should too since it's rear engine, that's a looooonng way for a shifter cable, so I'd go with the MD3060 electronic Allison with the electronic shift pad controller. That shift pad also allows you to pull transmission codes. So try to find you an 8.3 Cummins with an Allison MD3060. Make that your goal but if you have to settle or consider something else, come back and ask for opinions. Maybe you can find a complete rusted out bus, wrecked or burnt bus that'll never see the road again, but has the complete powertrain in it. IIRC, you can even get engine and transmissions out of dog nose front engine buses, since your rear axle gears are going to be reverse cut which is why the bus runs forward with the engine and trans behind the rear axle. I do believe that part takes care of itself.

As stated above, I would like to stay all mechanical, and I like the information regarding the mounting points.

I don't have a computer in this bus, I prefer it that way.

The Allison Transmission in the bus is an MT643, with the cable that runs ALL the way back. lol and it has a lock-up converter, just no OD.

My main concern is, is there enough space between the transmission and the rear hatch for a Cummins 8.3 to fit???

It would be great, and worth it to me to find a 1978 to 1990 Thomas Saf-T-Liner-ER or WestCoastER that came with a Cummins (and Allison would be a huge bonus). It never hurts to have a few extra parts available.

Thank you, guys, for your insight.

 

[s2mikon]

I used to work for a firm that had a fleet of 3208 cats and the owner also had a high end pusher motor home with one. They were reliable engines and good on fuel. They tended to smoke when cold after first start up on a cold morning. Sometimes they would blow a head gasket if you overheated it. These were being run in dump trucks pushing 50,000 pounds plus a back hoe on a trailer behind them. They had a hard life but held up well. He also ran a fleet of 6v-53 Detroits, also very reliable but leaked oil constantly. The Cats never leaked. You are correct they don't have replaceable liners but neither do 5.9 Cummins and nobody seems to care about them. Either way you will have to pull it to replace the head gaskets and with the heads off you can assess the cylinder wear. They were also reasonably quiet while running, and were governed at 2800 rpm and our drivers ran them against the governor all the time.

 

[Hooker-SKO]

I would love to stay all mechanical. My two Gilligs are Cummins 855s. Cummins is my first choice.

Head gaskets could be done, but the engine might not be worth the effort.

The Cat 3208 is a consumable engine. The sleeves can't be replaced (because it isn't a sleeved engine), so no real in-frame rebuild.

If the 8.3 will fit, that is what I am going to look for.
Thank you.



As stated above, I would like to stay all mechanical, and I like the information regarding the mounting points.

I don't have a computer in this bus, I prefer it that way.

The Allison Transmission in the bus is an MT643, with the cable that runs ALL the way back. lol and it has a lock-up converter, just no OD.

My main concern is, is there enough space between the transmission and the rear hatch for a Cummins 8.3 to fit???

It would be great, and worth it to me to find a 1978 to 1990 Thomas Saf-T-Liner-ER or WestCoastER that came with a Cummins (and Allison would be a huge bonus). It never hurts to have a few extra parts available.

Thank you, guys, for your insight.

An 8.3 will fit and bolt in. For all mechanical, find one up to 1996 model. 97 went electronic.

 

[cadillackid]

coolant in the oil doesnt mean the engine is shot.. that can happen from bad oil cooler or head gasket.. or obviously more serious things , but id look at figuring out where its leaking first..

 

[Booyah45828]

You have coolant in the oil, do you have oil in the coolant? Before the condemnation, might just be an oil cooler or seal.

As far as options, I think the 6v92, 3208, and 6ct were all available.

Being a 3208, I assume and of the midsize v8's will work: Cat 3208, DD8.2, IH 9.0. The cat would be the best of those 3. Cummins had some v8 options back in the day(vt555), but none were reviewed positively IIRC. I assume a 6v92 will work in what you have presently, I feel the 6ct, or any bigger inline 6 will likely require a different engine cover arrangement inside.

I'm sure one of the west coast bus nuts will be along shortly to set us all straight.

 

[IDoMy0wnRacing]

You have coolant in the oil, do you have oil in the coolant? Before the condemnation, might just be an oil cooler or seal.

As far as options, I think the 6v92, 3208, and 6ct were all available.

Being a 3208, I assume and of the midsize v8's will work: Cat 3208, DD8.2, IH 9.0. The cat would be the best of those 3. Cummins had some v8 options back in the day(vt555), but none were reviewed positively IIRC. I assume a 6v92 will work in what you have presently, I feel the 6ct, or any bigger inline 6 will likely require a different engine cover arrangement inside.

I'm sure one of the west coast bus nuts will be along shortly to set us all straight.

No, no oil in the coolant.
You wouldn't know by looking that the oil that there is a coolant leak.

Oil sample results from Blackstone Laboratories.

Thank you ALL, I appreciate the input.

 

[Booyah45828]

Man that's a bummer. The antifreeze % isn't much, so it's not a large leak, but as they said, it will likely continue to get worse. Cases like these an oil test really leaves no doubt on it.

Being an RE bus, I'd say it was likely run hot or overheated at some point and the heads have warped because of it. It's almost a guarantee on a 3208 that was run hot that the heads have warped. Afterwards they'll leak coolant when cold until the gaskets fail outright.

Hard to tell you what you should do. IDK what power rating you have, but the 3208t could have been up to 250 IIRC, and you'll be hard pressed to find a larger displacement/higher HP engine in there without switching to a straight 6 and changing stuff inside. A 6v71 or 6v92 would also likely fit, but some people don't like the noise associated with them.

 

[sportyrick]

Looks to me like that engine is pretty far back which may make it a problem like I had to shoe horn in a straight 6. Ask someone on here to take some measurments of their RE bus of comparable year with a straight 6 and compare notes. If the factory put that axle as far back as they could then a straight 6 won't fit. Is yours a turbo engine or not? I know someone who had one in a dump truck and just put head gaskets and bearing in it every 2 years because of problems just like yours. Everyone told me they are undepowered. I like your bus it looks nice so the effort is worth it in the long run rather than getting another problem bus from someone else.
There are all kinds of medium duty trucks on govdeals that are rust buckets and have low mileage and old enough to be mechanical injection, I see them all the time, lots of DT466 and 8.3 Cummins and yes occasionally a 3208 that you could just freshen up and install, maybe even with a better transmission.

 

[Bearmtnmartin]

If you increase engine torque you need to replace the transmission. The MT 643 is only good for about 600 lb of torque. Also the 3208 is quite a high revving engine and if you swap it with something else you may end up having to do rear end gears as well. The throwaway engine comments are usually from people who don't know anything about cat 3208 engines but they passed on some misinformation they read on the internet somewhere. An engine swap is many months and multiples of $10,000 even if you don't do the transmission. Your best bet is to fix the one you have and if you feel brave then turn the pump up a little bit for some more fuel. I speak from the experience of having had a 3208 and replaced it with something else. I'm happy I did it but I never recommend anyone else do what I did.

 

[ewo1]

Cummins might fit?

Cummins 8.3 mechanical

Overall Length mm (in) 1422.0 inches -> 55.98425
Length of Block mm (in) 856.0 inches -> 33.708
Overall Width mm (in) 977.5. inches -> 38.484252
Overall Height mm (in) 981.6. inches -> 38.645669
Weight kg (lb) 896


CAT 3208 - Marine engine

Weight 1250 lbs
Dimensions 48 x 48 x 40 in
Make Caterpillar
Model 3208
Engine Size 10.4, 320HP, Marine

I couldn't find the dimensions for a non marine motor but they are very close indeed.

Cat=48x48x40
Cummins=38x38x30

so the cummins motor is smaller in size?

 

[jimmythomas]

The Cummins is 56" long.
The Cat is 48" long? 40 wide and 48 tall?
A friend bought a dump truck with a "bad" 3208 -- He put a new air compressor on it and a new radiator -- Then he hauled a few hundred tons of gravel, he never did anything to the motor except dump oil in it, and it had about 500k on it. He sold it and made $$$.

 

[ewo1]

56 inches, I wonder if that is actual "block" Length or total length with the fan installed?

 

[Ronnie-SKO]

I have a newer saf t liner with the Mercedes 906, and 3060 trans. Nice combo. Love it.


Have to ask why do you want to get rid of the 3208? If the bus does everything you want why not fix it? The engine can be rebuilt, this "throwaway" engine idea is nuts. True it can not be done inframe, but that is not a big deal. If the engine does not use excess oil, and has good compression why not repair it. as others have said head gasket, and true up the heads. Not real familier with 3208s ( only have one in my care)but is there an oil cooler? if so check that for leaks. It is a real common failure on other engines.

 

[ewo1]

I keep looking at the pic of the bus and of the engine compartment. That really is one nice bus body!

Rebuilding the 3208 is a good idea if your happy with everything else.

A nice 8.3 cummins would be nicer with an md3060...Buy a donor bus?

Whatever way you go with this I think you'll do ok.

 

[Hooker-SKO]

I have a newer saf t liner with the Mercedes 906, and 3060 trans. Nice combo. Love it.


Have to ask why do you want to get rid of the 3208? If the bus does everything you want why not fix it? The engine can be rebuilt, this "throwaway" engine idea is nuts. True it can not be done inframe, but that is not a big deal. If the engine does not use excess oil, and has good compression why not repair it. as others have said head gasket, and true up the heads. Not real familier with 3208s ( only have one in my care)but is there an oil cooler? if so check that for leaks. It is a real common failure on other engines.

People use the WRONG Terms. The 3208 can be rebuilt, it's just that it can't be Inframed since it doesn't have wet liners is what I'm assuming. Like a DT466 can be rebuilt 100% to brand new without even taking it out of the bus. A 3208 would need to be pulled and sent to a machine shop to bore and hone the cylinders and then go with oversize pistons. Chances are, your bores are in good shape. You might consider just doing a RE Ring job and have the head worked over at a machine shop, and news seals and gaskets and I bet it lasts a very good long time. Unless you had a catastrophic failure, like dropping a valve into the cylinder, there's probably little wear in the cylinders. Diesel fuel is an oil substance unlike gasoline, so the cylinders wear much slower in a diesel than a gas engine, and is why diesel engines far outlast gas engines.

 

[Iceni John]

Someone mentioned a Detroit 6V92 as a possible option. Even though I love all 2-stroke diesels, I would not recommend a 6V92 because they make a lot more heat than a 4-stroke, so they need a larger cooling system. They're also much heavier (2100 lbs) than a 3208 and make more torque, so would the frame be able to cope with all that? And if you get a Detroit, make sure there's a good experienced 2-stroke mechanic in your area, because most diesel mechanics these days know nothing about them.

John

 

[Hooker-SKO]

Someone mentioned a Detroit 6V92 as a possible option. Even though I love all 2-stroke diesels, I would not recommend a 6V92 because they make a lot more heat than a 4-stroke, so they need a larger cooling system. They're also much heavier (2100 lbs) than a 3208 and make more torque, so would the frame be able to cope with all that? And if you get a Detroit, make sure there's a good experienced 2-stroke mechanic in your area, because most diesel mechanics these days know nothing about them.

John

100% agree with all of the above. I'll add, most of the good 2 Stroke Detroit meachanics have long retired by now, and many are even pushing up daisys. I do happen to know a great 2 stroke mechanic and that's all he talks about is the 2 strokes, and how people don't know how to set the racks and all kinds of issues on 2 strokes that newer diesel mechanics aren't even aware of, and most won't touch a 2 stroke. He happens to be 70 years old now. The EPA don't like the 2 strokes either, not in the least.

The only thing I think a 2 stroke goes into these days, would be an older restoration truck and that would be just for the nostalgia factor, not because it's the best option. You have to admit, then 2 strokes sound awesome going through the gears or humming down the interstate.