Dervish

You should fly over and rent a car, plenty of companies around that do it, seems a lot of the US guys are doing that now. I'm staying away from the standard Tourist days now though, it's just too damn scary with all the bikes about. Sticking to closed events now...

ivangene

Yea, I watched some vids and thought "HOLY CR@P" not interested in getting killed!!

good idea on closed days

Pac996

Like Macster says the worn valves stem guides and seals cause oil into the cyclinder after sitting. It burns off after starting. Just try holding paper at the exhaust to see if the paper has oil on it or more of a fuel smell.

During the 1-2 minutes is the engine running strong with no stuttering?
You say it all started after the compression check so I'm thinking maybe a center condutor of a plug had a seperation or the tip of a plug or two got dirt or knocked out of specs when being moved around. Plugs center cores take some major heat and become brittle in there. I'm sure prosches 100k miles life span of a plug doesn't fator handling them.

Anyway maybe try new plugs on at least the troubled side. Beats tearing the engine down
Pay attention to which cylinder each plug comes out of to diagnose which cylinders to keep an eye on. You can find pictures online to diagnose looking at plugs tips. Oil generally leaves the plug dirty and some time still oiled up

Dervish

It does stutter slightly until running clean, but only very slightly. I started her up earlier and watched round the back and you can definitely hear a stutter of sorts.

I'm taking it back to the place that did the compression test. It's just weird that all this happened right after they did the test. It had new plugs 9k miles ago. So can a plug cause the settling of oil and then smoke? I'll ask them questions regarding this.

Thanks.

Macster

Not necessarily. The hose that runs from the AOS to the intake manifold can end up depositing most (if not nearly all) oil on the intake walls that favor one cylinder bank over the other. At least this is true with the AOS and intake system of my Boxster. I have not been that up close and personal with a 996 engine's intake system and AOS though.

But if I'm right, in this case the smoking can be light to non-existent from one bank and of course heavier or only from the other bank.


Sincerely,

Macster.

Macster

That is a very smart observation regarding the compression test and plugs. Last thing touched...

If not a plug then possibly a coil was not installed properly or could even be bad?

Sincerely,

Macster.

Pac996

Macster I've got the deep laugh anguish in my mind after reading what you said. I remembered the the good old days and how if you are around long enough in cars you find some mighty percular things to remember when diagnosing.

More to the point of the deep laughing anguish feeling that overcame me. I'm sure you can remember some times of old where a buddy you hotrod with or others have gotten the firing order wrong when reconnecting the spark plug wires. I didn't think of it at first but it just came to mind. The car can seem to run ok with two plug wires reversed but it does run a lot better wired correctly.

Just another of the many things that can be checked.

Dervish

Thanks guys, will be on the phone to Porsche tomorrow and get it booked back in and have them check their work and possible AOS.

geldgrube

C'mon Dervish....what was the final outcome? You're keeping me in suspense as I have the same symptoms!

Dervish

UPDATE:

Well I went to get the low temp thermostat fitted (as per LN Engineering) and the specialist doing the work would rightly only fit after sticking a camera into cylinder 6 to check for health. Diagnosis was scored cylinder!
Long and short of the story meant new engine or rebuild. The specialist www.hartech.org is a very well respected Indy with by far the greatest watercooled R&D in the UK. We agreed on the rebuild route with modifications to try and prevent any future problems. The list being:
Overhaul cylinder heads (skim, de-coke heads & valves, re-lap valves to seats).
Re-build with new gaskets/ seals, new modified IMS bearing and spindle, new crank shaft oil jets, crank shaft bearings (big end, main & thrust), timing chain set & 2 guides.
Lower temp thermostat, modified cooling channels, new graduated head gasket (as 3.4).

Anyway, she's back with me now and I'm glad to say there's no smoke on start up anymore!

Topaz330ci

WOW what an update. Bill must of been expensive for all that!

Dervish

Just over 9000 of our finest English Pounds! (20% Tax f'kn UK government!!!)

redridge

wow.... what causes a scored cyl? You'd think everything will go through the air filter. Thanks for the update Dervish.

fast996

sorry if i missed it, how many miles did you have on it?

Dervish

The scoring is the result of poor design, simple as that. The 3.4 engine has graduated coolant channels, getting larger as you go around the engine from cylinder 1 to 6. On the 3.6 the channel and gasket holes are all the same size, resulting in cylinder 6 not getting as much coolant flow as 5 which doesn't get as much as 4 etc etc etc. The scoring is evident on the thrust side of the piston where the heat is greatest. I'm massively over simplifying things but that's the idea. It's all here for reading http://www.hartech.org/docs/buyers%2...20part%205.pdf There's a lot of info but 3.6 owners should seriously read it.

And for the record I had 51000 miles on the engine and was religious about oil changes, every 5k miles, and always warmed the oil (not water temp) fully before driving hard.