robss996

Hi all first time here, wish it was just to deliver flowers or serve drinks....just purchased 2004 40 anniversary 911 with 66k. Drove it from Florida to Canada. One of the cats failed coming up, dealer here fixed under warranty. Cylinder four is misfiring, flashing at idle and rough idle, goes steady at 2000 rpm and runs good. Coils good, injector good, plugs good, vacuum good, compression is down a bit in 4 170 vs 245-250 in the other 5 cylinders. Leak down done. Engine has been dropped and head removed and all checks out. Mechanic who is not a Porsche pro but knowledgeable, thinks it's rings in that cylinder, thinks car over heated and dropped a ring, claims he see's some whitening around exterior of cylinder. He is suggesting a full engine job with new rings, pistons, cylinders the works $$$$. YIKES . Could we not just do a cylinder clean up and do the rings alone,. the IMS at same time, maybe the head because now's the time.... Any insight/help would be hugely appreciated. This is my first Porsche the child hood dream is a bit of a nightmare. :$ Thank you and cheers rob ( umm no car wasn't PP-Inspec...I know)

Dharn55

The big challenge with this is getting new rings to seal. The cylinders tend to go oval and then new rings won't seal.

redridge

Wow.... that's a tough spot to be in. What codes were you getting.

Hurdigurdiman

Tough luck. The seller or PO needs a swift kick in the pants. Maybe you as well for not having it fully checked over before buying. Hope its all covered by warranty for you.

C4CRNA

Your first mistake is mechanic is not a Porsche pro!

philooo

yeah I am afraid that now the engine is open you kind of have to go with whatever your tech is telling you to do. Or at least make him change his mind, because I would not feel good going against the advise of the guy who will put my engine back together.

I have read a lot of problem on this forum but never heard of this kind of problem.

Opening the engine to check for rough idle is something I have never seen.

Engine rebuild is even harder to justify if this guy is not a Porsche pro.

Your best bet is to search and find someone who had similar problem as yours to see what solved it for them.

Marc Gelefsky

I have to disagree, I would get that car in whatever shape it's now in to a Porsche indy that knows the M96 engine well. Otherwise you may be in for a long painfull and expensive future.
Best of luck!

jumper5836

Sounds like your #4 has ovaled bad enough to cause misfires. I am practically in the same boat but not bad enough for misfires to happen. Just extreme oil usage.
I think if it's only #4 and the others look good then you don't have to do all of them but depending on what the tech says is what I would go with.

Kinda sad to hear the X51 engine with its extra rad and more oiling still has the same issues as the first gen 3.6l that I have.

jumper5836

Happens to more engines then the IMS problem. Thing is that depending on how bad the ovaling is that you could not even know about it. I have 2 local friends with a 3.4 and 3.6 that had it happen, plus my self. Talked to a indy and he has rebuild many 996 engine for that reason.
Thing is with IMS, the engine is toast so you'll her more people complain about it.

Hardback

Sorry to hear of your trouble with your new car. If you cylinder is ovaled then it would be a complete waste of time trying to add new rings. Also for the price of new rings you can practiaclly have new forged pistons AND rings. If your tech is not an expert on 996 engines I would seriously consider taking the car to a shop who has rebuilt these motors with good success. Speaking from experience here... My motor failed last year and I opted to upgrade to a 3.8L package from LN Engineering. Yes, the project was time consuming and rather expensive but I either had to buy a reman or rebore. I decided to rebore and take advantage of an unfortunate situation. With a 3.8 you will pick up almost 50 HP/TQ. Good luck with whatever you decide. Do not rush into anything. Read posts here and contact the experts before deciding on a plan.

fanny bay r1

Now this advice makes good sense to me!!

p.vanderlinden

Jumper, there is no third radiator in the 40th despite what has been published in some very expensive books. Nore is the exhaust sound package standard.

Hardback, 50HP from 200cc?

I just purchsed a 40th last month and all I can say is if the engine goes, I will not be able to afford the repairs. My fingers are crossed.

Cheers,
Paul

2K7TTMIA

Good advice from alot of guys here. talk to the folks at LN engineering if you don't have any good P-car contacts near you.

Hopefully you have some local Pcar owners in your area to give you some input.

Do your homework before you spend any $$ that may end up wasted.

And you get a new engine to boot!

soverystout

+1 I have no doubt about this. I can't speak from experience with my car but I have seen many others. All the more reason to stay on top of your cooling system.

I think (just my opinion) waiting for the water pump to actually make noise or fail falls into the category of excessive stupidity & neglect.

And this has been debated amongst many a thread but the lower temp stat (160) just works.

And keep those rads clean! This doesn't seem to be as important but the temp management of these cars can be difficult sometimes.

jumper5836

Yup all great advice. After my rebuild I will be doing the 3rd rad and LN Low temp sensor to prevent it from happening again.