Smoke in the mirror

[JohnyH]

This past Saturday while doing laps in my 88 roadster (driving it real hard) I had a very large cloud of blue smoke out the rear of my car. This was at the end of WOT and a long straight away. I thought I had an oil leak but after some investigation I couldn’t find one and the oil level was NOT noticeably lower! I have never had an oil leak and have never seen a puddle of anything but water from the AC condenser. Someone at the track said that its possible there is a build up of oil in the throttle body and when you let off of the gas it is consumed by the engine. Can someone tell me what happened? I just took the car to Carlisle and back, I drive it hard around town and have never seen this happen before?

 

[GeorgeT]

I had a similar problem with another car. The oil control rings were worn out: when you let-up, after WOT, there was a vacuum created in the cylinders that would suck oil past the rings.

 

[G Winter]

That could be worn valve guides or oil seals on the valve stems gone.
If that is the case you normaly would also notice it on startup. Oil seal on the valves can be replaced without pulling the heads but if it is the guides it would require a head job.also if it is the valve guides it could effect preformance as the valves might not seat the way they should .

 

[JohnyH]

I have never seen any smoke on startup, so I can't see it being the valve seals. It never is low on oil as I check before I take it out. It is a garage queen and I only take it out on sunny days, and then promptly drive it hard. Dry roads are more fun!

 

[Vettefan87]

How many miles are on the motor, and how hard has it been driven? Like roughly how many *hard* miles have you put on it.


Justin

 

[JohnyH]

There's about 75K Miles on it and the previous owner was a woman who had had it for 2 years (sedately driven). Before that I don't know the history, but I can imagine it has been driven hard sometimes, but not as hard as I'm doing it on the track! I guess a compression check would be in order?

 

[Vettefan87]

Yes that would tell you if the rings are bad or going bad, I would think. I would start there and see. Is that the first and only time it has happened since on the track?


Justin

 

[JohnyH]

The track is the only place I have ever seen it happen. It's really the only place it is really driven hard into and out of corners repeatedly and wide open throttle for any length of time. I have never seen it on the street but I do occasionaly drive it hard there also, since the smoke IS noticeable I think I would have seen or noticed it if it had happened on the street. I've only put, maybe a hundred miles of this type of track driving on the car.

I think a compression test is needed!

 

[G Winter]

I did some more thinking on this. If you run the engine at high rpm on a long straight,the engine pumps a lot of oil onto the top of the heads. It is possible that the drain holes in the heads for the oil are slightly plugged causing a puddle of oil on the head . When you close the throttle you have very high vacume and with the oil as high as the valve guides it could pull in a little oil.
If someone didn't change the oil regularly this could be something to look at. Do the other checks and if everything seems ok , pull a valve cover and take a look.

 

[JohnyH]

scav, thanks for the thought! The person I talked to at the track had the same idea as you, but didn't explain it as well as you have. There may be some truth to what you have typed and I will be doing some investigating when I put the car up for the SNOW season. Right now it's still on the road and I'm enjoying it TOO much! Don't fix what's not broken! (YET)!

 

[G Winter]

Hope you are lucky enough that this is the problem , not to costly a fix
remove the valve covers , clean on top of the heads as much as possible, take a round wire brush, such as a bore brush for gun cleaning and clean the openings on each end of the head. After you are done , flush the top of the heads with some cheap oil and then change your oil.If you really want to be sure things are clean you could pull the pan and clean it out, but don't think it is necessary. I have seen this problem in quite a number of engines. Olds v8 engines are real bad for it. I used to work as a mechanic about 20 yrs ago and still do most of my own work. Penzoil seemed to be the worst for leaving a dirty engine. Hope I am not to long winded.

 

[JohnyH]

Thanks scav!
Have a good weekend, shiny side up!

 

[BigRed]

When you do your spark plugs do a compression test this may tell you that your pistion rings are worn out. Also throw a master oil pressure gauge on it while doing this. This will rule out any possible oil/combustion leaks except for valve seal which ALWAYS go on these engines...mine included and ongoing