Cylinder 2 - broken wall ?

[paas]

I had my 01 996 c4 tip in for service today 40k kilometers. I had no issues really, but a small amount of white smoke at start-up occurs. The smoke first occurred after the car was washed earlier this year.

I picked the car up this evening, and they told me that the coils were cracked and replaced. The sparkplug on cyl. 2 where "muddy" which indicated broken cylinder wall !!?? Nothing they could do. Drive and change the engine sometime in the future, kiss and good bye.

Any advice from you guys ??

[phillipj]

Get a second opinion. Did you see the plug? What did it look like? Seems to me that if you had a cracked cylinder you would know it. How does the car run? I guess a "leakdown test" would tell you what was what.

Let us know what happens but definetly get another mechanic to look at it.

[txhokie4life]

Get a second opinion. Did you see the plug? What did it look like? Seems to me that if you had a cracked cylinder you would know it. How does the car run? I guess a "leakdown test" would tell you what was what.

Let us know what happens but definetly get another mechanic to look at it.

I would suspect that you would have intermix (oil in the coolant or vis versa)

I would perform a compression test first.

You could also pull the plug and boroscope it as you turn the engine by hand to expose

as much of the cylinder wall as you can see -- but it still might be hard to see.

mike

[Falcon900EX]

Get a second opinion. Did you see the plug? What did it look like? Seems to me that if you had a cracked cylinder you would know it. How does the car run? I guess a "leakdown test" would tell you what was what.

Let us know what happens but definetly get another mechanic to look at it.

I would suspect that you would have intermix (oil in the coolant or vis versa)

I would perform a compression test first.

You could also pull the plug and boroscope it as you turn the engine by hand to expose

as much of the cylinder wall as you can see -- but it still might be hard to see.

mike

It seems their is a lot of problems with cyclinders 2 and 5! Does it smoke everytime you start it??? Or only after it sits awhile? If the smoke is white odds are it's coolant. I wouldn't drive it tell you know for sure. E :unsure:

[paas]

I will get a second opinion!! The car runs great, after I got new spark plugs and coils the smoke has disappeared !! It smoked when it was cold for 3-5 seconds.

I think/hope it was the cracked coil that caused the plug to fail. It started immediately after I washed the car. Water on a cracked coil might be a problem.

[phillipj]

Scary what some shops will tell you. I find it harder and harder to find anyone that takes pride in their work and has integrity. Thank God for forums like this that allow us to do our own work and not fall pray to these Porsche pirates.

I would get it checked by another tech. Try to get a refferal. Have a leakdown test done to give you some piece of mind. I can't imagine how the car could run great with a cracked cylinder. If that were the case surely you would have some signs of oil/water intermix.

I'm no F1 engine builder but geez.....

[paas]

Now I worry!! The smoke is back, motor still runs great, but a puff of white smoke from right exhaust at start-up. After a few seconds the smoke is gone!!

I will have a Porsche race mechanic look at the car next week, but ....any ideas?

By the way thanks for your replies.

[phillipj]

Before you get too worried wait until your new guy looks at it. Then worry or not :rolleyes:

Could just be your AOS..

I hope you get good news

Edited October 23, 2009 by phillipj

[Dharn55]

Are there any traces of coolant in you oil or oil in your coolant? Easy to look and this will tell you alot. Look even before you take it to a mechanic.

[porsche1234]

First off getting a second opinion is always a good idea. Especially from your dealer.

2001 "seemed" to be the year that cracked cyl. walls were most common. Spark plug condition is an excellent way off diagnosing running conditions. Especially coolant in the cyl.

Borescoping the cyl is a good idea but may be difficult to see a crack b/c the crack will "shrink" when the motor is cold & get larger when motor is hot. And you have to have access to one.

If you do have a cracked wall the reason you're getting smoke on start up is:

-After shutting down the car when hot, there is still pressure in the coolant system. This pressure bleeds into the cracked cyl. Staying there until getting burnt off at your next start.

-When driving car, the combustion is greater than the coolant pressure & combustion will enter the coolant system. When this happens typically you'll get excessive dampness from around the coolant bottle.

Check:

-white smoke from tail pipes while driving

-continous coolant consumption with no visible external leaks.

-excessive dampness around coolant cap/bleeder (not always an indication of a cracked wall)

-bore scoping cyl.

-pressure testing system

[paas]

Traces of coolant in oil, or oil in coolant? How do I find out ??

I have NOT seen any smoke while driving. I have not registered any consumption of coolant fluid.

[Dharn55]

If you have oil in the coolant or vice versa it will start looking like pudding or sludge with a yellowish color. At first it may be just a few drops in the coolant tank, but if this is the problem it will become more apparant quickly. The oil will start to look like chocolate milk and you should be able to see it on the dipstick, on the filler cap and in the filler tube.

Do a search on the intermix problem and you will find lots of photos

[paas]

Good news I hope. no sign of oil in coolant or vs. Motor still purring like a cat, and there are no smoke while driving. No sign of steam from the coolant bottle !!???

This morning the car startet fine with no smoke !!

Comments ?

[paas]

I'm starting to suspect that there might be 2 isolated problems here, one the cylinder that burs oil, and second the AOS ??

The plug indicates burning oil, but there seems to be indications of problems with the AOS also.

I tried to loosen the oil cap while motor was running, and had to use a substantial amount of force, and when turning it gasped for air ?? RPM was rising when open.

Could this be connecting problems, or ??

[wvicary]

Has the AOS ever been replaced? The part has been updated and I would change it out. Easy DIY project and loads of write-ups on here for the procedure.

[Loren]

Sorry, but this all speculation - I highly suggest that you have a good Porsche shop inspect the car and find out what really is the source and cause of your problem(s).

[paas]

Thank you all for feedback. I go for your advice Loren. I'll let you know what the verdict is.

[Dwiggy]

First off getting a second opinion is always a good idea. Especially from your dealer.

2001 "seemed" to be the year that cracked cyl. walls were most common. Spark plug condition is an excellent way off diagnosing running conditions. Especially coolant in the cyl.

Borescoping the cyl is a good idea but may be difficult to see a crack b/c the crack will "shrink" when the motor is cold & get larger when motor is hot. And you have to have access to one.

If you do have a cracked wall the reason you're getting smoke on start up is:

-After shutting down the car when hot, there is still pressure in the coolant system. This pressure bleeds into the cracked cyl. Staying there until getting burnt off at your next start.

-When driving car, the combustion is greater than the coolant pressure & combustion will enter the coolant system. When this happens typically you'll get excessive dampness from around the coolant bottle.

Check:

-white smoke from tail pipes while driving

-continous coolant consumption with no visible external leaks.

-excessive dampness around coolant cap/bleeder (not always an indication of a cracked wall)

-bore scoping cyl.

-pressure testing system

If 2001 seemed to be the year with the most cracked cylinders, this post brings up a very good question.

Does anyone have a list of catastrophic failure causes according to model/production year?

For example, my98 996's could be known for RMS failure or maybe my99 996's are known for IMS but not D-chunk.

Research as this could be useful to those of us who primarily find holistic views of 996 catastrophic engine failure rates; as well as offer peace of mind. :huh::rolleyes:

Thanks,

D.

[porsche1234]

I agree with Loren. This is kind of a difficult problem to diag. by yourself. Get your car to a trusted Porsche dealer. good luck!