smoking running rough on cold starts

Hi,

Have a '05 Mustang GT with 50K miles on it. Just bought it in December. Notice, a few times, it's burning oil and running rough after it sits for a couple days. Smokes seems to be bluish white. Burns off and idles smooth after 30 seconds or so. Oil is clean...no milkshake. Wondering how bad this looks...$$$...???

Thanks

Very common symptom of leaking intake valve seals. As the engnie sits, oil will leak past the intake valve seals and collect on the back side of the valve. After the engine is started, it may run rough until the oil is burned off, and then runs smooth. An easy check is look at the spark plugs, if they have a "chocolate" color stain on the procelain near the electrode, or on the electrode itself, oil is getting into the combustion chamber....probably intake valve seals.

Thanks for the reply. If that's the case, what am I looking at for repairs...$? I'll check the plugs asap. Is this premature for an engine with only 50,000 miles? What causes it? Thanks.

Best to check around with local shops for a price. Several things could cause it/them to leak, could be the engine overheated causing the seals to harden and crack, could be a build up on the valve stem not allowing the seal to fit tightly on the valve stem, could be a defective seal.

Sounds like we're having the same problem.

I understand these can be changed by just removing the valve covers. I'm not a mechanic but try to do all repair to our vehicles. Are new valve stem seals something manageable to fix/install?

All information appreciated.

There are 2 ways to replace valve seals. One is to take the heads off and replace on the work bench and the other way is to use a compressed air fitting into the spark plug hole to hold the valve from falling into the cylinder while the keepers and spring are taken off and the seals replaced.

Ok sounds doable.

Is there a trick on proper reassembly of the valve assembly? Reason I ask had a Chevy 350 and a mechanic suggested after the push rod reached top of stroke tighten the adjustment nut 1.5 turns once the push rod would no longer spin between your fingers. Worked like champ. The engine ran great until we sold it. Any suggestions?

Thanks,

You can also feed some rope into the spark plug hole so the valve is held in place while you compress the spring and remove the keepers.
As to the valve clearance method you describe: hmmm. I wouldn't do it. Seems that is setting up for valves that stand open slightly. Better to have some slight clicking than to stand open.
(BTW, are the valve clearances even adjustable on the Mustang engine in question?)

Thank you