Why do precision turbos eat exhaust seals?

[Steve V]

This has happened to me and 2 of my other customers all with low mile turbos 500-3000 miles. 6157E turbo.... The fix is to replace the little piston ring type seal on the exhaust wheel and the center cartidge(thanks Bison). I redid mine(T type) last year and it is now good been about 1000 miles maybe. I have another customer that got a budget PTE TE60 from gbody and he's been chasing a leak at turbo drain. He brought me the car and oil is running out the hot side at turbine leaving a coked trail....not the drain. No smoke yet. Drips on oil filter. maybe 800 miles.

I have the same turbo on my personal Gn and guess what no leaks but at extended idle it starts to smoke and with have the smell of oil before it smokes...prob turbo as well. Maybe 3k miles.

All these cars have good feed lines...stock..braided...not restricted.

Good idle oil psi 15psi and up to about 30 35 on my GN.

Stock drains,braided drains.

Turbos boost fine otherwise.

No excess crankcase pressure all basics have been covered as I am not a noob to TR's.

Anyone else seen this.

Eventually I will go to a BB on the GN so not too concerned about it.

 

[chriss4655]

Yes exactly the same thing, 4431 brand new less than 1500 miles,smokes a bit on start up ,and you could see it leak oil out where the exhaust housing and the center section meet, dripping onto the oil filter.

 

[kidglok]

usually if the turbo seal is bad it should smoke all the time,

i had a problem with smoking at extended idle and it was the valve seals (champion heads with exhaust seals). One it reached operating temperature the exhaust got hot enough to burn the oil in the downpipe, it wouldnt do it when first started.

 

[Steve V]

usually if the turbo seal is bad it should smoke all the time,

i had a problem with smoking at extended idle and it was the valve seals (champion heads with exhaust seals). One it reached operating temperature the exhaust got hot enough to burn the oil in the downpipe, it wouldnt do it when first started.

I respectfully disagree. I have installed known good stock turbo and problem goes away. Reinstall suspect turbo and smoke/leakage/smell returns.

I have been down the road with exhaust seals,all heads that I touch have exhaust guides machined and positive seals while at the machine shop.

 

[scgnx2]

Yes exactly the same thing, 4431 brand new less than 1500 miles,smokes a bit on start up ,and you could see it leak oil out where the exhaust housing and the center section meet, dripping onto the oil filter.

Ditto...my PT-61 is leaking oil from the exhaust housing with only 3000 miles maybe.
Is there a write-up on how to replace those seals ? Never messed with a turbo before.

 

[porsches4lunch]

I Love Precision Turbos

 

[bison]

There may be more to this than the piston ring seal. I've disassembled turbos that had a lot of cokes oil behind the heat shield but didn't show visible smoke and nothing leaking out of the housing and the piston ring seal was ok. Reassembled with new bearing housing/piston ring and had leakage out the hot side. Anything that caused excess oil to dump out of the hot side journal bearing could be a problem. Balance could be a problem also. If the balance is out it will vibrate at certain shaft speeds and wear extra clearance into the parts creating more oil flow in the bearing housing. Usually if it's a drainback problem it's worst after spoiling and running under power for several seconds then letting off. The oil comes out highly aerated and will be able to back up and easily leak past the piston ring if the exhaust pressure suddenly drops.

 

[northerngn]

usually if the turbo seal is bad it should smoke all the time,

i had a problem with smoking at extended idle and it was the valve seals (champion heads with exhaust seals). One it reached operating temperature the exhaust got hot enough to burn the oil in the downpipe, it wouldnt do it when first started.

good to know my cars has the same heads and does the same thing...maybe look at opening oil returns in heads?

 

[Steve V]

There may be more to this than the piston ring seal. I've disassembled turbos that had a lot of cokes oil behind the heat shield but didn't show visible smoke and nothing leaking out of the housing and the piston ring seal was ok. Reassembled with new bearing housing/piston ring and had leakage out the hot side. Anything that caused excess oil to dump out of the hot side journal bearing could be a problem. Balance could be a problem also. If the balance is out it will vibrate at certain shaft speeds and wear extra clearance into the parts creating more oil flow in the bearing housing. Usually if it's a drainback problem it's worst after spoiling and running under power for several seconds then letting off. The oil comes out highly aerated and will be able to back up and easily leak past the piston ring if the exhaust pressure suddenly drops.

I have mainly seen it at easy driving. My cars don't smoke after/during boost. I did fix that 1 turbo with the parts you sold me about a year ago. All that was changed was the little piston ring and center section and bearings. Maybe these are a balance issue...I know one thing my stockers don't do this sh!t.
Wonder if a ball bearing turbo would be less like to have this issue?

 

[bison]

I have mainly seen it at easy driving. My cars don't smoke after/during boost. I did fix that 1 turbo with the parts you sold me about a year ago. All that was changed was the little piston ring and center section and bearings. Maybe these are a balance issue...I know one thing my stockers don't do this sh!t.
Wonder if a ball bearing turbo would be less like to have this issue?

The balance on a ball bearing cartridge needs to be even more accurate across a wider range of
shaft speeds since the cushion of oil isn't there to dampen any harmonics. Imo VSR balancing is the only way to go on those.