How to tell if turbo is bad?
07-22-2003, 08:41 PM
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How to tell if turbo is bad? The new turbo motor is smoking VERY badly out the exhaust. I have a feeling that the seal between the center section and exhaust housing is bad. The motor smokes quite a bit when decellerating (in gear) and a little at idle. It doesn't seem to smoke while accelerating, but it's kinda hard to tell.
The motor is fresh. It's a 40 over LT1 that I bought from AMS a short while ago. The heads were to have been rebuilt and the motor was to have new rings and bearings. For those keeping track, it's Joel Hester's old motor built by Hans Fuestel
Also, it takes a little while for the motor to start smoking. It will start smoking about 1 minute after starting. Each time it starts, the exhaust gas is reading 275-300*F on the pyrometer. that leads me to believe that the turbo is leaking oil into the exhaust and it takes it a while for the housing to actually "burn" the oil and start to smoke.
Boost is set as low as I can possibly set it. It's at 3 psi. Last week I had the car running N/A (the turbo was hooked up and blowing straight to atmosphere) and at first the motor smoked. However, after driving it for a bit, it didn't smoke much at all. Now, with the turbo blowing through the intercooler and in to the motor, it smokes again.
One problem I had was angle of the turbo drain-back line. It had a slight rise to it. Maybe an inch rise over 6 inches of lateral distance. I have since corrected that problem and the drain line is now sloping downward.
I've recently heard that a turbo that has been subjected to this type of situation will push oil through the seals and into the exhaust and/or motor through the exhaust housing and/or compressor housing, respectively. The person who told me this rebuilds turbo's for a living and said to just run the turbo and see if it'll come out of it. He says sometimes the seals are NOT ruined.
Any other opinions/thoughts/comments are appreciated.
Jesse Boyer
The motor is fresh. It's a 40 over LT1 that I bought from AMS a short while ago. The heads were to have been rebuilt and the motor was to have new rings and bearings. For those keeping track, it's Joel Hester's old motor built by Hans Fuestel
Also, it takes a little while for the motor to start smoking. It will start smoking about 1 minute after starting. Each time it starts, the exhaust gas is reading 275-300*F on the pyrometer. that leads me to believe that the turbo is leaking oil into the exhaust and it takes it a while for the housing to actually "burn" the oil and start to smoke.
Boost is set as low as I can possibly set it. It's at 3 psi. Last week I had the car running N/A (the turbo was hooked up and blowing straight to atmosphere) and at first the motor smoked. However, after driving it for a bit, it didn't smoke much at all. Now, with the turbo blowing through the intercooler and in to the motor, it smokes again.
One problem I had was angle of the turbo drain-back line. It had a slight rise to it. Maybe an inch rise over 6 inches of lateral distance. I have since corrected that problem and the drain line is now sloping downward.
I've recently heard that a turbo that has been subjected to this type of situation will push oil through the seals and into the exhaust and/or motor through the exhaust housing and/or compressor housing, respectively. The person who told me this rebuilds turbo's for a living and said to just run the turbo and see if it'll come out of it. He says sometimes the seals are NOT ruined.
Any other opinions/thoughts/comments are appreciated.
Jesse Boyer
07-23-2003, 10:06 AM
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Re: How to tell if turbo is bad? That is exactly how I found out my turbo was bad. It was fine until it warmed up, then it smoked like hell. One of my C clips was missing inside...the one that held bearing in place on the exhaust side. Time to get your turbo rebuilt.
07-23-2003, 12:44 PM
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Re: How to tell if turbo is bad? You can check the play on the impeller. Take off the intake side of the turbo and you should see a shaft with a nut on it. There should be very litte play in that shaft. Sometimes it will move side to side a very small amount, but if it moves in the thrust direction (along the direction of the shaft), it most likely has a bad seal.
-Geoff
-Geoff
07-25-2003, 07:49 PM
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Re: How to tell if turbo is bad? checked the shaft play... there is a very minute amount of play in each direction. The play in the direction parallel to the shaft is VERY small. Can there be a small, and I mean small, amount of play?
Jesse
Jesse
07-26-2003, 02:35 PM
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Re: How to tell if turbo is bad? Updates:
I pulled a plug yesterday and found it to be quite oily. However, this might be because I just moved it from one building to another and didn't give it time to warm up and get a clean burn... just thoughts.
I also pulled the turbo. The exhaust is very sooty, but not oily. The intake is slighly oily. So, i've decided to build a pipe that comes off the turbo tech. manifold and dumps to the ground. That way I can leave the turbo off the motor and see if the motor actually smokes. Sounds like a plan.
Also, I had the turbo looked at by guys that rebuild turbo diesel turbos. He said there wasn't much play in the shaft (in either direction), so it was acceptable. Also, he said if my seals were bad, i'd have a great deal of oil coming out of the intake or exhaust side (whatever side, or both, is bad).
So, i'll let you know what the motor does without the turbo on. If it smokes then, I probably haven't got the rings to seat yet. But, what are some other options if it burns oil? My dad thinks it could be crankcase pressure issue. However, if i had blowby, wouldn't I get a lot of pressure out of the oil filler cap when it's off?
any thoughts on all this??
I pulled a plug yesterday and found it to be quite oily. However, this might be because I just moved it from one building to another and didn't give it time to warm up and get a clean burn... just thoughts.
I also pulled the turbo. The exhaust is very sooty, but not oily. The intake is slighly oily. So, i've decided to build a pipe that comes off the turbo tech. manifold and dumps to the ground. That way I can leave the turbo off the motor and see if the motor actually smokes. Sounds like a plan.
Also, I had the turbo looked at by guys that rebuild turbo diesel turbos. He said there wasn't much play in the shaft (in either direction), so it was acceptable. Also, he said if my seals were bad, i'd have a great deal of oil coming out of the intake or exhaust side (whatever side, or both, is bad).
So, i'll let you know what the motor does without the turbo on. If it smokes then, I probably haven't got the rings to seat yet. But, what are some other options if it burns oil? My dad thinks it could be crankcase pressure issue. However, if i had blowby, wouldn't I get a lot of pressure out of the oil filler cap when it's off?
any thoughts on all this??
07-26-2003, 04:34 PM
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Re: How to tell if turbo is bad? More updates:
with the motor blowing all exhaust through the piping I built, there is absolutely no smoke what-so-ever. It's clean as can be. So, we've decided that it's in the turbo.
with the motor blowing all exhaust through the piping I built, there is absolutely no smoke what-so-ever. It's clean as can be. So, we've decided that it's in the turbo.
