Okay, I just bought the car, drove it around for about a week and it ran great and NO smoke whatsoever. The DAY AFTER I change the oil for the first time, it starts smoking. Now, a few days later, it's smoking like a chimney. What would you guys suggest I check on the car to possibly eliminate this smoke....I assume it's burning oil like a MF-er.
BTW, 1990 Firebird Formula - 305 TBI

 

HMMMMMM, where exactly is it smoking from? Do you mean out the exhaust? What color is the smoke?

 

Smoking out the tailpipes...a light bluish color

 

light blue is burning oil... could be sticky valves or worn piston rings or even just a bad pcv... have you checked over all your emssions components???

 

Sounds like it is burning oil. It could be piston rings, valve seals, and a few other things. How many miles are on the engine? Does it smoke more on start-up, or does it smoke all the time while running?

 

The engine has 130,000 miles on it, and it smokes most at start-up and acceleration off the line...not real noticeable while at cruising speed.
I appreciate the replies, what would you suggest I do first? The reason I ask is because my "engine repair" knowledge is very limited. As cheesy as it may sound, I have a Chilton's Manual and the ambition to fix anything myself .....I just hate to pay the Chevy dealer to fix it when the bill may be more than the engine is even worth

Thanks in advance for any help

 

Well, it is very likely that the smoke is being caused by the valve seals. Although, if the engine is smoking non-stop then it could be rings. Changing the valve seals is relatively easy, but might be time consuming.

 

And if it's the piston rings? Hard job?

 

If it is the rings, that would require a full rebuild. And since spending money rebuilding a 305 is a waste that would mean different engine.....

Valve seals is a VERY common problem though, and new ones can be had for under $40.

 

Okay, I'm hoping for faulty valve seals...due to lack of funds and time right now for another motor.
Thanks for the help!

 

You know, I posted some time ago, that my '90RS was smoking only on startup (compression is ok in the engine), so I presumed it was the valve seals, and everybody here agreed, that small blocks have this problem with OEM seals. Last weekend, I did about 3-4 runs down the local dragstrip, and the car is almost not smoking now on startup, guess it must have been some carbon deposits on the valves or something.

However, you mention that your car is smoking while you drive, and it happened the next day from your oil change. What oil weight did you use?? I think that if your engine has worn rings and seals, and you go to a very light oil, it can seep in easier than the heavier oil you had before, and that is causing the smoke.
Do an inital compression check. Then, replace the seals, and run the compression test again, to see if the pressure has increased, that would signal to a job well done. If not, it means your rings need replacement, and your engine some rebuilding.

Good Luck,

Thunderboy

 

Some oils, like Pensoil or something... from what I have heard gum up an engine. So, if it was all nasty in there from running an oil like that, and you switch to a different oil brand or type. You could be cleaning out the engine and that will reveal all types of things. Such as leaks, smoking such as your case.
Don't quote me on all that, but it's my take on what could be happening.. they also offer additives that you can add to sopt leaks, but that's pretty much the sams as using a heavier weight oil.

 

If possible find out what brand and wieght of oil the last owner used and try that.

 

One thing you might want to check, especially if the smoke is occuring on startup, is the oil return holes. It appears that GM did not do a very good job on cast de-burring during the later years of the LO3 in our cars. Sometimes the oil return holes were not properly de-burred after casting and, after a little buildup accumulates, it all but blocks off the oil return, allowing oil to sit on top of the head after shutdown around the valve seals and rocker arms. Thus causing the burning oil on startup, esp. if you have bad valve seals. Changing the oil in your car could have loosened some deposits, placing them in the already too small oil return holes. This could be the root of your problem, or not. I'm just throwing it out there as a possibility. If this is the case you will have to magnetize a drill bit and drill out the oil return, making sure to clean it regularly, flush the block with oil afterwards and change the oil again to avoid any complications.

 

Sounds like the previous owner used a thick oil to hide the blow by and/or valve stem seal leakage. You might try synthetic. It is less easily burned than conventional. But that could get expensive if you have to add it all the time.

And remember guys, just because an engine burns/leaks/whatever oil, that doesn't mean the lubrication requirement on the bearings changes. You don't want to go too thick just to avoid oil consumption. Then again, if it's smoking, you might care more about the short term (avoiding an embarassing blue smoke trail) than the long term (getting the most mileage out of it). Just my $0.02

 

i dont know if anyone said this yet but try putting in thicker oil... my friend had the same problem. he changed the oil and put 5w30 in and it started smoking the day after. we drained it again and put 10w40 in and smoke is almost completly gone...

 

That would be called treating the symptoms, but whatever floats your boat.
10W-40 isn't extremely thick or anything.

 

its thicker than what he was usin...the supercharger was just burnin the oil up like it was nothin...

 

Well if it's a case of forced induction, I sincerely hope he's using a good quality synthetic oil. With the temps associated with cooling superchargers and localized high engine temps, synthetic is a must...

 

yea its synthetic

 

Sounds to me like the old oil was of a very heavy weight, like 20w50 or somthing like that. Most of the time using a heavy oil will stop the leakage past the valve guides into the combustion chamber for a little while anyway. But it certianly wont fix it. I'd look into rebuilding the cylinder heads at least soon. A quick check to see if there is a lot of blowby (bad piston seals) is to pop the filter off the PVC tube coming out of the passenger side valve cover, with the engine running see how much smoke comes out, should be none. If there is alot then there is at least some blowby, a little is normal, a lot is bad. Also replace the PVC valve, its probably worn which can lead to high pressures inside the crankcase which in turn causes blowby oil to be pushed past the piston rings. Hope that helps.