North American Turbocoupe Organization



Smoking, how do I tell if it's the turbo, rings, or valves?
Kev Offline
Posting Freak
#1
My car started smoking a little about a month ago right after I switched to a synthetic oil. After talking with a few of the guys here, I decided that the oil switch and the smoke was just a coincidence, but I changed the oil again anyway with a heavier 20/50 mix thinking that maybe the seals somewhere in the engine were leaking just a little. The smoke slowed but didn't completely go away. I checked the compression and got from 155psi to 165psi across the cylinders, and was suprised to see those numbers on my 206,000 mile engine. I didn't find any oil on the spark plugs either. So how do I diagnose from here? How would I check to see if the valves are the problem? Or are they ruled out since there is no oil on the plugs? The car doesn't smoke at all on start-up, it takes it a few minutes to start smoking after it's warmed up, and you have to look for the smoke for about 5 minutes from it being barely noticeable. After that first 5 minutes, it is a slight, but constant blue smoke. You can't see the smoke when you are driving; it is so slight. After playing with the car racing around with a buddy the other night, I noticed the smoke was pretty bad when I pulled into my driveway and just sat there waiting for the turbo to cool down. When I was checking the compression, I also checked to see if there was oil in the intercooler or throttle body and there was only that light, dry film that is always there. I took the PCV valve off (motorcraft, 6 months old), and cleaned it out and gave it the red-cheek blow-through test, and it is fine. It wasn't even that dirty. I'm gonna run the codes later today and I'll post what I find, but I was just wondering right now how to check the stuff that may cause this problem. Thanks for any and all replies, and sorry for this incredibly wordy post.

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Kev
88 TC 5spd Black body, red leather, K&N in front of the radiator, Gillis boost valve at 17 psi, polished throttle body, 2 1/2" dynomax ultraflow mandrel bent duals. 255 lph fuel pump, ported exhaust manifold, totally rebuilt head with Melling cam kit and a little port work
Kev
1988 TC 5spd
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Pete D Offline
Administrator
#2
Your compression # are real good for 206K. I don't know that yopu can rule out a ring problem, compression rings can be good and not the oil control rings, but that may not be your problem. Clean plug may help support this

The fact that it doesn't smoke on startup would tend to say it isn't valve seals or guides.

My guess would be the turbo seal on the turbine side. This would allow oil to burn in the exhaust system, not affecting the plugs.

You can check for shaft play in the turbo, but remember that shaft play doesn't always mean bad seals and you can have bad seals without shaft play.

Nice write up! Keep us posted
Pete Dunham


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TCorBUST Offline
Member
#3
You exactly described what I saw on my car when my turbine seal was going out.
http://natomessageboard.com/Forum1/HTML/010946.html

My turbo was a T3, but I bet even an IHI would have the same type of leaks.

I couldn't completely see the problem on my car until I had the turbo off the car and then took the exhaust elbow off. The turbine wheel was very wet with oil, but no play and still very smooth when spun.

I guess you might be able to see some wet oil through the o2 sensor hole if it was bad enough. If you can take off your exhaust elbow, that should really help diagnose the problem.
'88 TC 5sp, K&N cone, t3.60/.63, ported head, Felpro 1035, Walbro 255 hi pres., Kirban FPR., 3g Alternator
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Kev Offline
Posting Freak
#4
Thanks for the replies guys. I hope it's the turbo since that would be the easiest to change, but I went ahead and ran the codes and this is what I got... During KOEO, I got a code 63. I did a search on this code and saw that it was the TPS voltage so I checked it. It was at .93 volts and pretty smooth throughout it's range. I have suspected the TPS in my idling issues for some time now, but it checks out fine when I check it, maybe it's just a little sticky and can only be seen with the car running. I don't know. During the KOER tests, I got a code 25 (knock sensor, I didn't tap), and code 34 which is the EGR valve according to the search function. I have an autometer vacuum/boost gauge hooked up in my car and I'm getting 20 on the vaccum side at idle. My car has the green/black EGR vacuum fix too so I don't know what else to do about that. But here is the strange thing, while doing the KOER tests, the idle gets high as it should and then starts idling down in increments as it should, but when it gets to about 1500 or so, it just drops to 0 and the car dies. The only way I could finish running the codes with the engine running was to give it gas during that fall-to-zero period, then I could let off the gas and it would idle rough while giving the codes, the idle was around 750rpm or so during this time. After the test, I turned the key off and restarted the car and it idles smooth at around 1000 rpm. Hmmmm?

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Kev
88 TC 5spd Black body, red leather, K&N in front of the radiator, Gillis boost valve at 17 psi, polished throttle body, 2 1/2" dynomax ultraflow mandrel bent duals. 255 lph fuel pump, ported exhaust manifold, totally rebuilt head with Melling cam kit and a little port work
Kev
1988 TC 5spd
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Pete D Offline
Administrator
#5
Your vacuum at 20" is fine. Your code 34 is normal.

Not sure on the idle issue. Was the code 63 a KOEO or a CM code?. Also the TPS test does not always catch a bad one. If this is the original one w/ 200+K miles, you might want to splurg and put in a new one [Image: biggrin.gif]
Pete Dunham


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B_Lieder Offline
Senior Member
#6
your base idle is too low, that is why your car is dying during the engine running test. start the car and warm it up. Then unplug the IAC (you'll probably have to goose it to keep it alive). Set the idle to 800 rpm's then shut her off and re-adjust the TPS. My car did the same thing, (stalling during engine running test).

Hope this helped.
Bill
Bill L
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Kev Offline
Posting Freak
#7
Code 63 was constant memory during KOEO. I'll try resetting my base idle and see if that helps with running the test, thanks Pete, TCBust and Bill. I'll keep ya posted

Kev
Kev
1988 TC 5spd
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JT Offline
Posting Freak
#8
A CM code 63 would indicate a possible intermittent issue with your TPS circuit, or the sensor itself. Make sure to check your connections at the TPS and EEC. It is recommended to perform the "wiggle test" on the circuit for this code.
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TurboE Offline
Posting Freak
#9
Keep an eye on the turbo or do some preventative maintainance if its a daily driver. About a year ago with little warning just a little louder turbo spooling noise and then white smoke like i couldn't believe out the tailpipes i counldn't even see the cars lights behind me. Not saying you will experience the same just wanted you to know what could happen. Oil was obviosly everywhere, cat, intercooler, TB. I don't think the IHI liked where i had the gillis valve set at (my own fault for not buying a boost gauge).

[This message has been edited by TurboE (edited 08-10-2004).]
-88 TC Black
5spd, Precision SC50 T3/T4, QH/SD Tune, Gillis, AFPR, 255FP, WB O2, K&N, Ported E6, 3" DP, ATR 2.5" Duals, 3:73 Rear, Konis, Eibachs, 18" Voxx Wheels, X Drilled Rotors.
-06 G35 Coupe Diamond Graphite
-97 Pathfinder
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