Heavy Oil burning SC

[AlanP]

Hi there,

May I introduce myself...my fiancee was given by her mother a lovely 1983 911 SC that she has owned since new. It's done only around 42k miles and is in great condition. Sadly though, the other week, it started pouring out white smoke and has burned a litre or more in a few minutes. We had it towed home and I was planning to get a friend who is experienced with these cars to have a look at it for us. He reckons it could be a broken head bolt, saying that there was a period when this weakness existed. However he keeps putting us off, so I have two questions:

1. Any recommendations for a good independent expert on these cars in the Leatherhead/Dorking area?

2. Does it sound like that's a likely reason for the burning? I found oil in the air cleaner, so it's probably getting pushed into there from the oil tank overflow. The car still runs very well although still smokey...it had to be started to get it in the garage.

Thanks in advance for your advice.

Alan

2003 Maserati CambioCorsa
1978 Laverda Mirage
1997 Ducati Superlight

 

[dij999]

I wouldn't be as pessimistic.
Oil gets sucked through a through a breather into the induction side of the engine from the oil tank and causes the symptoms you have. I had same issue a few years ago and is considered to be a not-infrequent issue after a lay up.

Unfortunately I don't know your area but I expect someone here will.

Dave Jones

 

[mkck]

Don't suppose you'd recently changed / topped up the oil had you?

Could be a simple overfill. I had identical symptoms after changing the oil and mistakenly putting two litres more in than I should have.

Billowing white smoke.

Dropped a couple of litres out and all normal again.

Just a thought.

Not sure about the head bolt thing....Rebuilt my engine last year, had a couple of broken head bolts, but hadn't been smoking at all before rebuild (had a few oil leaks, hence the rebuild).

 

[AlanP]

Well, I am wondering about the oil level thing...I changed it a while ago though, and although we don't drive it often I'm sure we did take it out once or twice since. I think tomorrow I'll divert the overflow into something else and see if it's still pumping through which would indicate the oil system being pressurised by a gasket leak... I have to say I still expect the worst!

Thanks for the advice,

Alan

 

[Old and Slow]

Hi,
My SC is in for head bolt replacement, the symptoms are noisy "exhaust" sound when driven hard, very unlikely that oil is getting into the cylinders. Yours sounds like overfilling the oil level. In the SC the level should be a little above minimum on the dipstick and you'll find the oil level gauge shows half-full or more.
For a contact, Russel Lewis at RSR Engineering is near you, 01428 602911, but don't contact him just yet as I want my 911 back and the fewer distractions the better!!
Regards,
Philip

 

[AlanP]

Thanks for the replies...I wonder if it does have to do with oil level, however it's seemingly not pumping oil into the air filter housing now, yet still pumps out white smoke in large quantities. I'll have to get it looked at by someone with a bit more experience of the cars...I certainly don't feel confident with this type of engine.

I'll report back once the reason is clear.

Cheers,

Alan

 

[dij999]

Be good to hear eventual diagnosis - if not over-filled I still think its a vacuum creation issue and oil aspiration from the tank and not an internal engine issue.
All you describe is same as my previous situation - removing the oil filler cap from the external tank (temporarily!) stopped it and replacement of a
collapsed breather pipe solved it.
The breather hose enters the induction system downstream of the airflow sensor plate (why you get a vacuum leak when the oil filler cap
is off and engine running, you will note engine speed rises) and so you may not see oil in the filter housing which is upstream.

DJ

 

[AlanP]

That's why I love these forums...that is the kind of thing I was thinking might be happening, and so I tried running it without the tank cap on and it stopped smoking...well more or less! This breather, which is it, the one to the filler tube?

Cheers,

Alan

 

[dij999]

the one to the filler tube?

Yes it has a swan neck shape which is inclined to collapse with age.

There is a small brass vacuum restrictor funnel inside the breather hose at the filler end which you will need to refit if you do it yourself.
I also had to replace crankcase breather hoses at same time - if you don't have access to a parts diagram to see what there is, try the Pelican Porsche parts website - google them - good advice there too.