High oil consumption. Possible turbo seal?

[oddshot]

My M35a2 has had high oil consumption since I bought it 10+ years ago, about a quart in hundred miles. The engine starts and runs great, idles fine and has plenty of power. No odd noises. It does smoke, black smoke, on the road, but not much sitting still. It smokes more than some but not as much as others.

The truck is a 68 that went through the rebuild program. I bought him with 12,000 on the odo and now he's up to about 37,000. Never run hard, never overheated. It's got a couple little leaks, but not much to talk about. Barely leaves a drip in the driveway. It's NOT blowing oil out of the exhaust.

As I recall, it's got a D turbo on it. Unfortunately, I had a computer crash and lost ALL of the logs and records I kept on this truck.

I've always been suspicious that it has a leaking turbo seal.

I'm a life long auto mechanic, service manager and shop owner. I have a degree in AUTO (not truck and not military trucks) tech and my ASE certs, so actually doing the work shouldn't be a problem. I do have questions.

1. Is my oil consumption related to the turbo? My thinking is there is no way to find out. If the leak is on an "inboard" going to engine side, I don't think that there would be a trace of a leak, the pressure produced by the turbo would just blow the oil into the engine.

2. Will this engine run OK without the turbo? I've been led to believe that the only reason the turbo was installed was to reduce smoke signature ... not for more power. Can these things simply be removed?

3. I've done a bit of searching and read that parts for the turbo are hard to come by. Does that include turbo seals?

4. I've never rebuilt or resealed a turbocharger. We always sent them out for rebuild or installed a new one. Come to think of it, the only modification I have ever done related to turbos, was the installation of a RUF twin turbo kit onto a 930. That has got to be over 30 years ago. Is a seal replacement something that I can do without a lot of special tools.

And finally the big scary question:

5. Could I be risking a "run-away" given the high oil consumption?


I would really appreciate any advice, suggestions or help you might share.

 

[Gypsyman]

What troubleshooting have you done? Have you pulled the exhaust to check for oil buildup? Have you pulled the inlet and outlet piping on the compressor to check for oil or for residue on the compressor wheel or inside or the piping?

As for number 1 in your post if the oils is leaking into the compressor you will in fact have a mess in the piping going to the engine inlet.

 

[patracy]

Turbo oil seal failure can be a risky thing to keep pushing. You can potentially get to a point where it's in runaway. No amount of pulling the fuel stop will shut it off. It will either blow itself up or suck itself dry of oil and lock up when this happens. Sometimes you can save it by shifting into 4th or 5th and using the brakes to stop the engine, if your clutch lasts. 1 qt every 100 miles is certainly cause for concern.

The turbo can leak from both sides of the center. Oil will be present in the charge air pipe and intake if it's on the intake side. And oil out the exhaust pipe if it's on the exhaust side. You'd also likely see excessive white smoke on the exhaust side.

What kind of blowby do you see out the slobber tube below the turbo?

Yes, the LDT can be ran without a turbo. But honestly you'd need to swap so many parts, it doesn't make much sense to do that. Just find a replacement turbo if it turns out to be the actual turbo that has failed.

 

[oddshot]

Turbo oil seal failure can be a risky thing to keep pushing. You can potentially get to a point where it's in runaway. No amount of pulling the fuel stop will shut it off. It will either blow itself up or suck itself dry of oil and lock up when this happens. Sometimes you can save it by shifting into 4th or 5th and using the brakes to stop the engine, if your clutch lasts. 1 qt every 100 miles is certainly cause for concern.

The turbo can leak from both sides of the center. Oil will be present in the charge air pipe and intake if it's on the intake side. And oil out the exhaust pipe if it's on the exhaust side. You'd also likely see excessive white smoke on the exhaust side.

What kind of blowby do you see out the slobber tube below the turbo?

Yes, the LDT can be ran without a turbo. But honestly you'd need to swap so many parts, it doesn't make much sense to do that. Just find a replacement turbo if it turns out to be the actual turbo that has failed.

Yeah ... I knew about the horrors of a runaway. I've never let him run low on oil. I put spin on oil filter adapters because I hated that 8 second delay for oil pressure to come up.

4 years ago I had rotator cuff surgery on both shoulders. I also had both knees done. I parked Henry (my truck) back then and haven't touched him since. We're having some work done in the back yard and Henry needs to be moved. I charged his batteries and he fired up and ran just like he always has.

I just turned 72 and I'm afraid I'm going to have to start making some decisions I really don't want to make. I really love that old truck. Power Steering would be great, but I don't think I can do the work or afford to have it done.


OK ... The slobber tube never occurred to me. I'll check that.

My lack of experiance with turbos caused me to think otherwise about oil in the hoses & exhaust. I'll pull those and check for oil.

BTW ... the smoke is BLACK and there is no oil blowing out of the stack.

I won't be able to do the work until the work is done in the back yard.

Thank you VERY MUCH for your kind replies. I really appreciate it.