Smoky start-ups

[easelboy1]

My 1983 911sc is smoking on cold start up. Seems to be regardless of time sitting (next day or days in between start ups). It is blue--oil related smoke. My mechanic had me change back to mineral based oil as apparently it was running synthetic. Seemed to clear up the problem for a week and now back to the same old tricks.

What should I try next? Have been told--this is the nature of the car. But my 80 Targa does not do this and it is even running synthetic....

[ZOA NOM]

Valve guides are worn. You will live with it until the smoke bothers you enough to have the top end rebuilt.


edit: Welcome to the forum, sorry your first posts involve a problem with your car. You'll have plenty of help here, though.

[easelboy1]

Thanks Zoanas for answer and welcome--guess I need to buy a mask...would a worn guide valve produce an oily sparkplug or some other symptom that I could check against to confirm diagnosis?

The mechanic was quick to rule the Valve guide issue out. Figured I had overfilled oil. Then used incorrect oil....

[jwernquist]

Just a little thought, I have had 3 911s now, 2 of them smoked on startup just a bit, not much but it was there, never any time else, So all i do is when I put the car away i let it idle for a minute or so and next time no 9-10 times no smoke, It always seems to work.

Just try it strangely enough it works!

[ZOA NOM]

You very well could have overfilled, but that should go away. If it is continuing, then it just about has to be the guides. The only other path for oil to be combusted is past the rings, and if the smoke goes away once you're on the road, the rings shouldn't be the problem. Worn guides will weep oil onto the top of the valve by the port and it will be waiting there when you start up. It burns off, and away you go. You can live with it for many miles, but it will get progressively worse and should be addressed at some point. Do a search here for worn valve guides and see what you can learn. I would check the plugs to see what the combustion process looks like. It might give you a hint. In general, smoke at startup that goes away is most likely guide related.

[dshepp806]

What made the mechanic "figure" you overfilled?

Best,

[easelboy1]

Easy first assumption because technically I am a newbie. And I think the overfilling is a pretty common first timer mistake judging by the threads on the forum. So I heated everything up in a nice hour and half drive into the "country" and rechecked--as it was only 1/2 qt above the minimum level line so I had plenty of room to overfill if I wanted to! Next suggestion was to move to a mineral based oil...which seemed to fix problem for about a week...and yeah, my buddies are scratching there heads over that one too...it did however produce non-smoking starts during that time...

Must say it is rather interesting how there appears to be a division between folks suggesting 911s will smoke and 911s don't smoke...

[ZOA NOM]

Anyone claiming 911's don't smoke without any other qualifier is just blowing smoke up your...

The 3.2's have a reputation for worn valve guides that causes precisely your symptoms. I am not surprised at all to hear of those symptoms in a 3.0

[85carrera]

i also heard because its a flat boxer design oil can leak past the rings into the combustion chamber while the car sits.

my car smokes on occasion. sometimes more than others. sometimes never.

[rnln]

Originally Posted by ZOANAS

You very well could have overfilled, but that should go away. If it is continuing, then it just about has to be the guides. The only other path for oil to be combusted is past the rings, and if the smoke goes away once you're on the road, the rings shouldn't be the problem. Worn guides will weep oil onto the top of the valve by the port and it will be waiting there when you start up. It burns off, and away you go. You can live with it for many miles, but it will get progressively worse and should be addressed at some point. Do a search here for worn valve guides and see what you can learn. I would check the plugs to see what the combustion process looks like. It might give you a hint. In general, smoke at startup that goes away is most likely guide related.

In that case, I think it would affect performance, does it?

[84toy]

It could be worn guides or rings. If the guides and seals are shot it should smoke when running and be using oil as well

My guides were worn .015 and didn't smoke at all on startup but it did idling when hot. Same engine overhauled smokes a puff at startup and none the rest of the time but it only has 300 miles on it. Clearly the rings haven't seated yet.

I think the "occasional" smoker can be rings. The oil rings rotate around and if it happens to stop with the gap on the bottom it could get a little oil past the gap when shutdown.

[Wavey]

Originally Posted by jwernquist

Just a little thought, I have had 3 911s now, 2 of them smoked on startup just a bit, not much but it was there, never any time else, So all i do is when I put the car away i let it idle for a minute or so and next time no 9-10 times no smoke, It always seems to work.

Just try it strangely enough it works!

+1. This is common practice, and if your guides aren't terribly worn it should help a lot. I always try to do this, and don't get start-up smoke when I do. On the occasions when I'm in a hurry or forget - startup smoke returns.

Welcome to the forms!

[2ndTARGA]

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[willf]

not wanting to get into the "what oil is best discussion..." what weight and type of oil are you using? I had a 79 911, that when using Mobil 1 synthetic 20/50 (redtop), it would smoke a bit at startup... when running castrol syntec 20/50, it wouldn't. My 80 911, was running dino oil (Pennzoil) with the previous owner and smoked at start up as well as puffed smoked from a high rpm decel. I was thinking valve guides also. I moved over to Rotella 5/40 Synthetic and after about 1k miles, i have no smoke on decel and rarely any smoke at startup, especially if I let the car idle for a moment prior to shutting her down. I think the chance to idle prior to shut down gets most of the oil in the oil tank versus leaving it in the engine.

BTW, Welcome!

[easelboy1]

Willf, I am pretty confused by the oil arguments so I welcome some clarification. Have switched to 20 / 50 Castrol. Was using 15 / 40 Pennzoil.

Will try the post drive idle. The neighbors will appreciate the car more

[willf]

net is that I have experienced different behaviors depending on what oil I have used in my 911s. going to 5/40 Rotella synthetic for example made the smoking go away for the most part. With that said, I would hate to see someone jump the gun and go after replacing valve guides, etc when I have seen oil alone appear to swell up seals and take away a less than desirable behavior. Did not mean to confuse.

[2ndTARGA]

I actually agree that idling helps somewhat with my own smoking problem, but I really don't get it........ could it be a placebo effect?

We all know 2-3 quarts leave the tank as soon as you shut down (thus the rookie overfilling syndrome) so any effect of idling on where the oil ends up would seem to be short lived. And besides, for a scavenger system designed to work well at 6400 RPM, can there be a huge difference between idling at 1K and cruising through a parking lot or driving up your street? How idling would make a day and night change in the amount of oil left above the valve guides is a mystery to me.

But then, as I said, when I let it idle it does seem to help - I think.

My main problem is that my car smokes with no particular consistency. Just when I think it has to be guides, it won't smoke at all after sitting for weeks. Then, after driving a lot and having no smoke issues, I'll suddenly fumigate some innocent bystanders (who've no-doubt just admired my car)

I drove a '75 Targa for 50K miles from new and it never smoked - not once. So I have issues with the "it's normal for horizontal engines" argument - even though I obviously fell for it when the PO used it on me (and may want to use myself if I ever decide to sell before I fix this)

Thanks to the starter of this thread and for all the tips posted so far - I'll start working on the oil selection and keep an eye out for additional suggestions.


Ron

[jwernquist]

I know it seems crazy but somehow the stupid idling thing works, I have messed with it countless times, and I know a few others who practice it as well, is it a placebo who knows, however it just seems to work. I had a car that I ran Mobil 1 Synthetic is after breakin and it smoked really good on startup however the if i let it idle it wouldnt. So then I changed to castrol 20/50 and even if I didnt let it idle it wouldnt smoke. Now I run Mobil 20/50 and I very very rarely get smoke on startup. If it's been sitting for a week sometimes it will smoke a couple puffs and sometimes it wont!

Who knows, mabey some of the experts can chime in on the idling issue. Interesting thread!

JW

[vreference]

Reciprocating engines in Helicopters (R22 and 300c) have to be cooled 2-3 Minutes before shutdown. They are a pretty close relation to the Porsche air cooled engines. This is to avoid coking in an engine that has been run close to 100% rated output but a cool down period is not out of the question for street going engines.

[Wavey]

Originally Posted by easelboy1

Willf, I am pretty confused by the oil arguments so I welcome some clarification. Have switched to 20 / 50 Castrol. Was using 15 / 40 Pennzoil.

Yikes. You should read the oil thread:

http://66.236.61.177/showthread.php?t=367300&page=1

Currently at 41 pages, so pack a lunch.

The idling-before-shutoff thing definitely works. Nothing placebo about it. Similar to Steve Wong's chips in that regard