Blue smoke after boost

SilvrEclipse · #1 12-15-2006, 11:17 AM

After I boost the car I get a good bit of blue smoke coming out the exhaust. I know that blue smoke means burning oil. As long as I am on the throttle there is no smoke but when I let off and the car is slowing down, especially when still in gear, smoke will puff out the exhaust. The turbo I put on there was used but seemed to be in excellant shape. Still has very little shaft play. I haven't had to time to do a compression check but I was just hoping this is a sign of the turbo going bad.

Mikelb · #2 12-15-2006, 11:22 AM

I'm having a bad day and can't really think through things... but I might suggest checking the PCV valve... I know if that's bad it can build up pressure and cause piston ring blow-by... and I'm thinking that if the pressure can vent enough under boost, it might still have a problem venting when the TB is closed...

(forgive me if this sounds irrational, I'm having sugar problems this morn and can't think clearly)

SilvrEclipse · #3 12-15-2006, 11:24 AM

The PCV valve is pretty new, I can still check it out to make sure.

Mikelb · #4 12-15-2006, 11:29 AM

hmm... 420a @7psi... I'm trying to think... it might be awhile (waiting on everything to clear up...I didn't eat breakfast this morn and I'm suffering now)...

I remember your car, but I can't member when you got it turboed... how long has it been turboed? and when did this start?

And a/b where do your EGT readings sit?

What kind of shaft play has the turbo got? side-to-side? or in and out? some side-to-side is ok, but there should be no in and out...
I would think if it were the turbo, it would be dumping oil when under boost...

Have you checked your intercooler? if the turbo is really bad, there should be oil in there...

SilvrEclipse · #5 12-15-2006, 12:08 PM

It has been boosted for a little over a month now. The turbo has no in/out play. My EGT's only hit 1400-1500 under boost. Im not sure how long it has been doing this, I can't see the smoke, you have to be driving behind me. But I believe that it has been doing this for a little while, it seems to be getting worse though. I will have some time next week to check everything out. Im still leaning toward the turbo because if I dont boost I dont get any smoke.

gthompson97 · #6 12-15-2006, 04:19 PM

A simple 5 min compression test could tell you alot. Rings that are *going* bad will most likely smoke under extreme pressure (under boost) but not while coming off. I'd say check the turbo.

jonnyboy9012 · #7 12-16-2006, 02:12 AM

Hey... i had the same problem when i turboed my PT (with a motor similar to the 420a... it is acutally a sub-division of that motor called the "EDZ"). The problem did turn out to be the turbo.I couldnt figure the damn thing out, i checked all the crankcase lines, compression checked... basically everything i could think of. I turned out to be the turbo seals on the inside, i bought a cheap ebay turbo (i know... i know, but i already got what is deserved and i was broke at the time) that lasted great for about 2 weeks, the outside of the turbo itself was of excellent quality but where the saved money was on the bearing housing, the seals where shot and it would blow oil. It blew oil because the seals had worn to allow tollerances to fall out of spec... i dont know how many thousands of an inch are supposed to be between the journal bearing and the shaft, but i know mine was enough to cause blowby. I still dont have an explination on why it did it when i lifted on the throttle, but it did... and the seals where the culprit. Hope this helps.

eclipsed at 3am · #8 12-18-2006, 06:25 PM

your egt is 1400-1500 under boost? damn. i dont know if naturally-NA motors that are turbo'd run hotter than a naturally turbo car, but i know on my car, under full boost of like 20-21psi, my egt is about 1250-1300 and stays.

maybe your car is running lean. that could be heating up your engine and causing rings and whatever else to heat up really bad, and possibly fail. i dunno just my two cents. i cant really say a lot because i dont know much about 420a-turbo.

my 91 gs turbo puffed out a little blue smoke when i boosted. it was all stock. when i put another stock turbo on, the smoke stopped. maybe it is just your turbo. hope you figure it out, smoke and nasty smell coming out of the exhaust is embarrassing!

Mikelb · #9 12-19-2006, 08:28 AM

ok... I'm not sure here... but I'm gonna say with EGTs that high, I think you're running lean... bump up your fuel compensation a little, and see those drop... I'm not certain on this, but that's why I gave everyone else some time to look and see what they thought.

I am definitely leaning towards the seals in the turbo... from what I've read, it looks to be the culprit... I think that the bearings are allowing it enough shaftplay that once you come out of boost it blows the oil by and comes out the exhaust side...

SilvrEclipse · #10 12-19-2006, 10:38 AM

I beleive that the EGT are fine, when the motor was n/a they would sit at 1400 @ 70mph. 1500 if the a/c was on. Also remember that the 420a has higher compression than the 4g63. I am going to try and get the compression tested this week. The motor is suppose to be hot right?

EDIT - I searched around on 2gnt for a little while and found out that on a good tuned motor they should be 1500-1600. So I am running a little bit rich.

gthompson97 · #11 12-19-2006, 07:30 PM

I wouldn't lean it out anymore though, just to be safe. Do you have a different turbo you can put on and test?

SilvrEclipse · #12 12-19-2006, 11:03 PM

No, thats the only turbo I have. I can't lean the fuel out anymore, actually I can't adjust the fuel at all. Im just gonna run the turbo and see how long it takes to breaks. I might even put a 16g on it. Would there be any noticeble difference in performance?

jonnyboy9012 · #13 12-20-2006, 02:16 AM

If your going to have the turbo on their for longer than a couple weeks try some heavier weight oil... it helped mine stop smoking so bad for a little bit, but it still smoked like Ron White on a welcome back tour. And it will get worse very quickly so keep an eye on oil levels. I finally said enough is enough when a cop pulled me over and gave me a fix-it ticket for the sight and smell comin' out my exhaust. Good luck.

SilvrEclipse · #14 12-20-2006, 07:53 AM

Well damn, I just hope it will last a couple more months. Im going to the track tonight so we will see what happens. Hopefully it wont blow up

Mikelb · #15 12-20-2006, 08:18 AM

eww.... I wouldn't suggest running a car hard unless you have its problems fixed first, b/c then it will develop new ones...

You don't need to run it hard until you know that it's really the turbo and not the motor, or that it could be running lean...

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