951Porschiste

I've recently noticed that when I start the car after it has sat for a few days that there is blue smoke coming out of the exhaust for the first few seconds and a smell of burning oil. Plus the exhaust pipe releases a spray of oil drops. If I turn the car on while the engine is warm, there is no smoke and no oil spray.

Should I suspect
1. Worn valve guides?
2. Worn piston rings?
3. Anything else?

If so, how big a job is it to
1. Replace worn valve guides?
2. Replace worn piston rings?

worried

hosrom_951

Most likely not the piston rings, a loss of compression/leak down test would comfirm this.

Sounds more like valve seals, a full cylinder head rebuild would be needed (it would be kind of stupid to remove the cylinder head and replace just the valve seals).

KLR

How much oil do you use? Typically, you'd wait on valve guides until your oil consumption is approaching the edge of spec. On the bright side, if you're still on the original HG, it's probably only a matter of time until you would need to do this job anyway.

951Porschiste

If it's the valve seals, there is no need to pull the engine, right? But if it were the piston rings then the engine has to be pulled?

Jeremy Himsel

You don't have to remove the head to replace the stem seals. You can pressurize the cylinders to keep the valves from falling into the cylinder. I've also used nylon rope in the CC and then rotated the piston twords TDC.

RKD in OKC

Could also be turbo bearings. Easy way to check is to pull one of the intake pipes and see if it has any oil in it.

Peckster

Start with a compression test. Testers are cheap, and you're just guessing without that info.

Oil spraying out of the exhaust sounds pretty bad, are you sure it's not water?

hosrom_951

RKD in OKC: That is a new one for me regarding the turbo.


951Porschiste: You are correct regarding what needs to be pulled off, but as KLR mentioned, if your running the stock HG (like i am) it would be wise to go ahead for a full head rebuild while your at it.

As long as your oil consumption is within spec (manual indicates up to 1.5liters/1,000kms) then your rings should be fine. But again as mentioned, testing (compression and leak down) would detrmine what needs to be done.

951Porschiste

Definitely not H2O, it's oil. Again it only happens on a cold startup. Does not happen at all when the car is warm or running.

What would be the use of the compression test? Finding if a specific piston is leaking?
I understand the leakdown test allows you to pinpoint if the leak is from the intake valves, the exhaust valves or the head gasket. Correct?

Peckster, do you know if compression test kits and/or leakdown test kits are available at Canadian Tire?

hosrom_951

A compression test would see the condition of the rings/pistons. A healthy engine should see a max of 150psi across all 4 cylinders (some get 140-145psi) and it should be done when the car is at operating temp and with a WOT.

An old trick used is that if you get low CR numbers, add some oil into the plug hole and re-do the test. If the compression number go up by a margin, then probably you have a piston ring issue.

Don't worry, bad rings have high/out of spec oil consumption and smoke issues while driving. It's more likely something in the cylinder head instead.

fast951

If the problem is taking place only when it's cold, then one of the followings is a probable cause:
- Bad valve guides/seals - Oil leaking from the head to combustion chamber after car sits for a while. This could also cause smoke under heavy vacuum.
- Rings are out of spec when cold, then seal better when hot. This can be tested with a leakdown test cold then hot. It should show variation, if the rings are a problem.
- When cold, there is a possibility that the cold start setup is VERY rich and washing the cylinder walls.. Not likely, but possible.. Easy way to test it is to warm up engine, unplug engine temp sensor, and plug connector to another cold sensor..

RKD in OKC

Oil cooled turbos have oil seals. Those seals can leak. When they do it is typically on cold startup or after they have sat a while like valve guide seals. The big difference is that valve guide seals do not oil up the piping from the turbo thru the intercooler to the intake as do turbo oil seals.

It is a lot easier to check. Just pop off the top pipe from the intercooler with the banjo bolt and see if has oil in it.

951Porschiste

Thanks for the suggestion. I've had the car for 18 months now. The PO had the turbo changed about a year before I bought the car. If there indeed is oil in the IC pipes, then am I looking at a new turbo? Should I still go ahead and do a compression and leakdown test anyway?

951Porschiste

fast,
Not sure I understand what you mean by plugging connector to another cold sensor...

KLR

Bear in mind that a light film of oil in the IC pipes is typical. If you have lots of oil, turbo seals could be your culprit. Spitting out unburnt oil through the exhaust would sound more like a turbo issue (i.e., post combustion chamber problem). Most people seem to lose the HG before the other components in the head give up.

For those who have done it, if you have the head off for an HG and reconditioning, how much additional work is it to replace the turbo with a rebuilt unit at the same time? Both jobs are probably beyond my DIY capability given time limitations these days, so I've been wondering when I eventually have to do one or the other (hopefully not for a while) if it would just make sense to do both at once, save on the labor, and be done with it.