Smokey 993! Help

[Adom]

Morning to all, your help would be greatly appreciated. Not for my car (thankfully), but I've just got off the phone to my brother who is touring France in his 993 C2. When the car is warm and idling, he can see some blue smoke predominantly from the left bank, and the car is clearly consuming oil whcih he is topping up. At all other times, he says it is unnoticable with the car still performing fine. He is quite concerned it may be something major, and still has to nurse the car back another 600 miles or so to get back to England. Anyone got any ideas what it might be? And should he continue to drive it back to Blighty?

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[Spridget racer]

Oil comes out of the exhaust either because it is getting past the rings or past the valve seals. Either way it is not good news and will require the cylinder head off (at least) when he gets back.

Possible causes:

Nibbled piston due to detonation/poor fuel/high temperatures

Knackered rings

Valve stem seal gone

Burnt valve/seat

If engine sounds fine and performance is not noticably worse it is unlikely to be imminently terminal. It is more likely to be a head problem. Performance will be effected but he may not notice at normal speeds. Compression test and leak down test will point to the cause.

I wouldn't drive it 600 miles, but if he doesn't have recovery, as long as he is sensible he'll probably be OK. If it gets worse, stop. Engine rebuilds are expensive.

If he has been trashing it, it may be that he has burnt off all the carbon inside the cylinder head and has exposed worn rings or poor valve seats which were already there.

Hope this helps

Richard


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[Griffo]

Is it possible to rule out over filling the oil? When running hot the oil level guage shouldn't go past the 10 past 2 position, which is still someway before the indicator red level. The other thing to check would be if any other grade of oil (thicker for example) has been used (e.g for topping up) over what normally gets put in the engine. Sometimes that can have a similar affect.

Griffo.


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[Spridget racer]

If it's an over fill why is it coming predominantly from one side? IMHO If it has been overfilled it comes out of the breather not the exhaust

Richard


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[Used Porsche]

If its a high milage it can be valve guide wear. The book on 911 Performance by Bruce Anderson - page 188 - (ISBN 0 7603-0033-x) (MBI publishing) specifically mentions accelerated valve guide wear due to overhot 964 and 993 engines. His veiw is that the engine sound reduction plate below the engine causes excessive temperatures and valve guide wear eventualy leading to valve stem failure and a big bill.

Quote - "for the 993 I recommend removing the engine sound trays. Even though they are not as restrictive as those on the 964, I feel they will be responsible for the 993 running hot.We have seen indications that the 964s run too hot with these sound trays because all of the engines that we have seen apart have had excessively worn exhaust guides."

Drive home at a moderate pace in my opinion - and then do the checks mentioned above by spridget racer.


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[WillD]

How about the occasional puff of smoke when starting up from cold. Not everytime but rarely, now and again after an "enthusiastic" drive say the day before ?




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[Used Porsche]

My 32000 mile 993 has done this every few days and so did the 150,000 3.2 Carrera before it.

I have heard that brand new boxters and 911's do it too. Its a flat 6 engine which can allow this to happen.

Its due to oil seeping past the valves and into the combustion chamber which gets burnt when you start the car.

I dont think its a problem - anyone have a different view?


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[James Ball]

Agree with Stevo. Perfectly normal. As long as it doesn't either a) continue to smoke, or b) smoke under acceleration you don't need to worry about it.

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[WillD]

Thanks.

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[Adom]

Thanks for all the suggestions, I think he's resigned to the fact that the head will need some attention on his return - in the meantime, as its still running OK, he thinks the recovery will not come out as its not actually broken down. He is going to nurse it straight home and just keep a very close eye on it on the way. Thanks again.

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