Hey guys,

I recently submitted a thread regarding smoke coming out of my exhaust and asked about leakage past the piston rings. I got some replies suggesting a compression or leak down test first to determine whether it was a premature ring failure issue or not.

I just recently got some other input from someone saying it might be a valve sealing problem and that a compression or leak down test wouldn't matter ( but i guess it wouldn't hurt to do it anyway ), but my question is, how much does a valve job generally cost ( if that is the issue ) for a car like this? Could it be done while doing the timing belt? Any help in this area would be great.

Again the smoke coming out of my tailpipe is more on the white side but it usually only happens for the first 20 seconds or so after I start the car up. there is a odor to it but i can't make it out. It does not smell sweet like antifreeze, so I don't know.

Thanks
2000 A6 4.2

 

How many miles do you have? Does it ever overheat?
The valves have seals on their stems, which may be replaced while on the engine by putting compressed air in to each cylinder through the sparkplug hole. Unfortunately, the camshafts and lifters have to be removed, so you would also want to do the timing belt. There is information on an A8 site about the 4.2L engine: http://www.audipages.com/Tech_Articl...echanical.html

 

Our antifreeze does not smell sweet at the pipe. If it is white not blue or blue grey. It is most likely a head gasket failure. So try this;

Start it and fan the exhaust into your face, Does it feel more humid then oily? Does it dissipate like steam?

Check your fault codes for a misfiring cylinder. If you have one pull the spark plug when engine has sat for a while and would normally blow smoke.Use a hand held vacuum pump to suck whatever is in the cylinder out. You have to angle it down to the bottom. This will determine oil or water.

Or It seems to me it's water because smoke is BLUE water is WHITE. You could drain a little antifreeze,(about 1 Liter) pour Bar's leak that mixes with antifreeze and follow directions. If it's your head gasket that will plug it for now. Then you decide if you want to go for a valve job $$$ later.

If it does turn out to be seals, It can be done with the heads on the car, It is a big job though. $$$.

You Yourself need to determine exactly what is causing your problem because you don't want to replace seals when it's burning antifreeze not oil.

 

to answer your question ac6hw, it has 148,000 miles on the car and about a month ago it was overheating a little one day( meaning the needles was moving past the middle ) when I was running the car with the ac on for about an 1hr and half. I wasn't doing any rough driving but a consistent 60 to 65 mi. per hr that day, for about an hr and a half. The car wasn't smoking or anything like that and the coolant light did not come on but I could tell it was getting there.

Since then it hasn't done that but then again I haven't really driven it that long in one given period since then either.

 

You really need to over heat it to cook the heads.

Determine if it is oil smoke or if it's steam from coolant. Try looking at your coolant res. If it's getting low it's going somewhere.

Try placing your hand close to the tail pipe on start up.
If it's oil it will be blueish and steam is white. That's the first step. Figuring out what's burning.

 

20 seconds of smoke when you first start the vehicle could easily be just a rich fuel mixture. If it does it when the vehicle is warm look elsewhere.