Well the other day some guy in a new Cobalt SS tries to race me from a 40mph rolling start and I noticed that after about 4,000 rpm in second, it just started letting out a little blue smoke. It calmed down for a second after it made the 2-3 shift then after about 4,000rpm again it started smoking. The car will not smoke all the way up to 6,000rpm in first or during free-revving in neutral or park.
I've heard old school Ford guys joke around about the 302's sucking down oil through the valve stem seals during high-rpm for that "upper cylinder lubrication". Is this common 302 or should I look into replacing my heads(not worth replacing the seals when I already have GT-40P's waiting in the wings). I'm almost certain it's not the rings, the car never smokes during idle or under initial load...just seems to be under heavy load for extended periods of time. Also, the plugs NEVER look oil fouled.
How many miles on the rings, Thats how mine started, eventually got worse it was blowby, an engine showing it's age. If it did it at 4k RPM that not considered high RPM. If your going to tear down anyway in the furture to replace the heads, It would be in your best interest to do the rings and pistons as well. you can get entire rebuild kits with rings and pistons, bearing and all gaskets for about 300 if you not going to use a power-adder. To get the forged piston they are a little more expensive.
The actual mileage of the engine is unknown...the car said 254k on the odometer but it looks like a rebuilt engine. It NEVER smokes at any other time...probably just pulling oil through the valve stem seals.
that is normal . it is sucking oil around the valve guides. valve seals are probly toast or getting close to it.
That's what I figured, just wanted a second opinion.
Thanks,
Don
so who won this little race?
What cam are you running?Some cams are known to cause a little smoke,as the b303 i'm running,as an example.Tends to load up a little bit every now and then especially after a hard run and then a near idle situation.I worried when this first happened,but like a week later,i read about the cause.The bad thing is ,i can't remember where i read this info.Sorry!
Might want to look into that a little more, I have built and seen several B-cams that never smoked, somethings not right might be minor but the cams should not cause smoke unless something is off.
To little info and to much guess work.
Plus if your racing why are u looking behind u.
IF u have a carb then it could have been a little rich.
If it is FI maybe tune up is a little off?
U start there, If its so much smoke u can tell what it is and your sure iys blue smoke then it should do it on start up after its been sitting all night. Valve seals when going or gides will leek little oil down the valve when parked, Thats why get blue puff when your car has been sitting over night or a few hours, Slight puff is not to bad, More smoke as wear gets worse.
Rings unless u have one broke or alot of wear dont smoke on start up but do in higher RPM. simple leak down and compression test can help here.
Other things that i have seen are intake gasket sucking in Oil from under the intake. I lost a good motor becasue of this. I found out that oil in one hole and spary are bad and the piston was not happy with the mix.
I was looking behind me to see how far back this little queer was(that should answer 2 Q's for the price of one). It NEVER smokes any other time as I had previously stated and when I got the motor, the cylinder compression tests read between 125-130...that was about 10k miles ago. In my experience, I've never seen an engine produce such close results across all 8 cylinders. BTW, I'm running the stock HO cam w/Mark VIII ECU '91.
SirChirpALot, you may be a little(but not too far) off in your valve guide seal theory...blue smoke upon start-up, that goes away after warm up, is usually a combo of worn seals/loose guides, just worn seals won't cause smoke upon start-up(unless they're completely rotten and there is nothing left, in which case they would smoke non-stop). There doesn't need to be "a lot" of smoke for someone who knows what they're doing and lookin at to tell what color is is. It clearly wasn't white(coolant) and it definitely wasn't black(rich), I could see the bluish tint to it.
BTW...it's not my "tune-up", runs a factory '91 LSC ECU with '91 HO engine which is internally stock, full length headers, K&N filter, off-road h-pipe, dynomax super turbo lers(dumped), and I run AR133 plugs when it's above 50 degrees, during winter, I run Autolite 25's. I also have my base timing set at 14*.
It's already been agreed upon that it's typical 5.0L to suck down a little oil through the seals at higher RPM, especially for extended durations.
Only problem i have with your assesment is 4k isnt high RPMS and you stated it stops after 4k, up to you on how you handle it, after all its your car, I would do a freshing up on the block with rings and all. your going to have to eventually anyway, Might as well do it before you cylinders get to bad.
Yeah, well 4k rpm is high compared to cruise rpm (1500-2200). I didn't say that it stopped after 4k...it started right around there then calmed down for a second after the rpms dropped due to the 2-3 shift(shifted from 2nd gear @ 5400rpm)...then came back again in 3rd gear at about 4k rpm again.