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2G Valve seals or Bad Turbo?

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Project97GST

Proven Member
42
4
May 24, 2017
Pekin, Illinois
So, sorry if I couldn't find this and it was answered. If it has been then please link it!
Anyways, after completing my new motor installation after my last spun its bearings I notice I have a similar problem my last engine had. Same exact turbo and head keep in mind. After driving for a little, when I stop at a light I have blue smoke come poring past me. Like kind of a lot. This doesn't always seem to happen when I stop and so it has me thinking maybe turbo seals? When I pulled the last motor out I did clean some oil out of the intercooler so maybe it could be doing the same thing. So what I am thinking is maybe when I get it into boost it is sucking oil in and then burning it and I see that at the stop sign? When I drive calmly it doesn't seem like it really does it. Also when I start it fresh it doesn't shoot smoke either. Should I preform tests, or just rip my intercooler pipe off and check for some more oil?
Thanks in advance guys!
 
Definitely do some tests, but I'm thinking bad turbo seals. Since this is the same turbo from your spun engine, did you happen to check the turbo for damage from bad oil? Have you had any changes in power under boost?
 
A turbo with bad seals is easy to pinpoint by looking at the CHRA for oil deposits coming out of the back of the compressor wheel. If you changed the engine, you must have seen them. If you saw oil, then the turbo seals are done for unless you are getting massive amounts of blow-by from your head.
 
Definitely do some tests, but I'm thinking bad turbo seals. Since this is the same turbo from your spun engine, did you happen to check the turbo for damage from bad oil? Have you had any changes in power under boost?
I actually feel kind of dumb for not further inspecting the turbo but the only thing I checked was shaft play and it was perfect. As for power under boost it is hard to say, the previous motor was bored and stroked blah blah so they are very different monsters anyhow.
A turbo with bad seals is easy to pinpoint by looking at the CHRA for oil deposits coming out of the back of the compressor wheel. If you changed the engine, you must have seen them. If you saw oil, then the turbo seals are done for unless you are getting massive amounts of blow-by from your head.
How would i check blow by? This motor has a breather on it i dont know if that matters.
 
How would i check blow by? This motor has a breather on it i dont know if that matters.

If you have a breather on the valve cover and the hoses are not connected to the intake tract but you had oil in the intake piping then your turbo seals are definitely in need of replacement.

If you do have hoses from the valve cover to the intake then it depends on where you see the oil deposits. If it's in both the intake tract near the hose and on the turbo outlet it might be blow by, but if it's only the turbine area and specifically in the outlet then it's turbo seals.
 
So I check the hose that goes to the bov and also the intake. There is no sign of any oil going through there so once again I think my culprit is the turbo. Btw its a stock t25 turbo for the 97 gst. I assume this is a common issue.
 
So I check the hose that goes to the bov and also the intake. There is no sign of any oil going through there so once again I think my culprit is the turbo. Btw its a stock t25 turbo for the 97 gst. I assume this is a common issue.

Yup, if you cannot see any oil on that hose it means there is no significant blow by through the engine. That means the oil you found is bad seals from the turbo. T25's are notorious for blowing seals, time for a turbo rebuild or swap (I'd pick the latter).
 
Oil will continue to come out regardless if you are on or off boost. It will take longer to reach the intake tract due to reduced flow but it will continue to smoke. Turbines don't stop rotating off boost, they just rotate slower which reduces oil passage through the seal.
 
Oil will continue to come out regardless if you are on or off boost. It will take longer to reach the intake tract due to reduced flow but it will continue to smoke. Turbines don't stop rotating off boost, they just rotate slower which reduces oil passage through the seal.

Right. With keeping clean oil and temps down do you seen it getting worse?
 
There's really nothing to do to keep it from progressing. It will continue to deteriorate because the piston seals are a wear item. Metal to Metal sealing will always have a finite lifespan. Cooler oil will be thicker hence it will seep less but it's really hard to use a car and not get oil to the operating temperature, and it's detrimental to the rest of the components. Also, you are seeping oil into the chamber and if you have a catalytic converter you will soon be clogging it. I'd say, get a rebuild kit as quickly as possible and get it fixed, there's no band aid to a blown turbo. Hope this helps.
 
There's really nothing to do to keep it from progressing. It will continue to deteriorate because the piston seals are a wear item. Metal to Metal sealing will always have a finite lifespan. Cooler oil will be thicker hence it will seep less but it's really hard to use a car and not get oil to the operating temperature, and it's detrimental to the rest of the components. Also, you are seeping oil into the chamber and if you have a catalytic converter you will soon be clogging it. I'd say, get a rebuild kit as quickly as possible and get it fixed, there's no band aid to a blown turbo. Hope this helps.

It helps a lot thank you so much. Glad I have no cat . I checked the intercooler pipe and it looks like some coolant maybe seeping in too. Well for a 20 year old turbo I am not suprised really.
 
It helps a lot thank you so much. Glad I have no cat . I checked the intercooler pipe and it looks like some coolant maybe seeping in too. Well for a 20 year old turbo I am not suprised really.

If there is coolant in the piping there is a bigger issue than a turbo. The coolant passages of the turbo don't meet the oiling system unless the chra is broken inside and if that were true then you'd have coolant in your crankcase. Coolant in the intercooler is an extremely rare symptom. Are you sure that's coolant?


As for the rebuild kits, TurboLab works great. Have used their kits with a lot of success.
 
If there is coolant in the piping there is a bigger issue than a turbo. The coolant passages of the turbo don't meet the oiling system unless the chra is broken inside and if that were true then you'd have coolant in your crankcase. Coolant in the intercooler is an extremely rare symptom. Are you sure that's coolant?


As for the rebuild kits, TurboLab works great. Have used their kits with a lot of success.

The coolant was really a maybe. Could just be a little condensation because I know there isn't coolant in my oil. And thanks a lot I will probably but from them for sure then!
 
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