Start up smoke after sitting a while

[widebody911]

So last night Serge944 dropped by, and in the course of setting the right height on the 911 and other projects, the question of how long it had been since I'd driven the car came up, and whether it would even start. So I said "only one way to find out" and I fired it up. It had been a month or so since I'd driven it, and it took almost 10 seconds to fire up, but it did and the idle actually held like it was supposed to...

But the smoke! Oye! I've had a little 'startup smoke' before, but this was insane, and it just didn't quit! I let the car warm up, then then gassed it a little, and the smoke just kept coming; it seemed to thin out as I revved it up, and then dumped a bunch when I let up. When you're thinking to yourseld "Hmm... Dry chem or halon?" that's too much smoke.

This seems like an assinine question from someone with over a decade of 911 ownership, but I the last time I had an engine smoke this bad was a VW bus with water-contaminated oil.

It wasn't doing this when I pulled it into the shop!

Any clues, or do I just need to drive it until it clears up?

As an aside, I ran into a friend of mine this morning; he lives two blocks away: "So, I heard you fire up the race car last night..."

[pwd72s]

Thom, I'd suggest going for a drive, see if it clears...I'm thinking it will. Also double check your oil level if it smokes on decelleration...this may be an overfill thing.

[asphaltgambler]

I have had this happen to a couple of customer cars that sat for a peroid of time; like two weeks. Started it up and you'd think some removed all the rings! Have'nt had a tech explain why. My guess is oil draining and filling the crankcase.

[HardDrive]

I have had this after 2 weeks of sitting. Big puff of blue smoke. But it cleared up pretty quick. No smoke after 8-10 seconds. Car has 83k.

[beavis911]

My '78 did the same thing only it sits for a month or more some times (at least it used to). I had the engine out a few months back. While it was out I pulled the CAT off because there was oil leaking from the exhaust flange. When I looked in with a light, there was a noticeable amount of oil sitting in the exhaust pipe maybe 1/8" deep (mind you this had not been started for 3-4 months, we had a nasty fuel leak front & back). I asked this question on an earlier thread and the consensus was normal for a little oil leak into the exhaust pipe, the longer it sat the more oil that leaked. Bottom line was start it and drive it a little more....I wouldn't drive it because of the heat here and it would run hot so I bit the bullet and installed a Carrera cooler with a fan. Now it don't sit so much...

[Joe Bob]

Normal.....just letting you know that it's pissedoffthat you let it sit that long....now go drive it, spank it, kiss it and put it away wet.....geez, the questions on this board....

[Dottore]

I also get this occasionally - though not quite to the degree you describe. The smoke always disappears after 10 or 20 seconds. I have been told this is absolutely nothing to worry about.

What puzzles me in the inconsistency of the phenomenon. Sometimes there is a lot of smoke after the car has been standing for only a couple of days - and other times the car stands for several weeks and there is no smoke whatsoever. WTF?

[bigchillcar]

maybe be it depends upon how hard it was driven at the last shutdown..if you shut it down relatively cold, perhaps you had less oil seepage, etc. and the next start sees less smoke as a consequence..or maybe it should be the other way around..just a thought since it's a inconsistency.
ryan

[Blanco]

Originally posted by Dottore
I also get this occasionally - though not quite to the degree you describe. The smoke always disappears after 10 or 20 seconds. I have been told this is absolutely nothing to worry about.

What puzzles me in the inconsistency of the phenomenon. Sometimes there is a lot of smoke after the car has been standing for only a couple of days - and other times the car stands for several weeks and there is no smoke whatsoever. WTF?

Same here... I tried several combinations of hard driving and easy with immediate shutoff and it seems to be inconsistent. Sometimes it smokes other times its doesnt.

[mjshira]

not to bring up a bad point but that sounds like valve guides to me. common weak point of the 3.2 and 3.6 engines. And as we know you have a H E A V Y foot ;-) maybe you should check that!?!

[Bill Douglas]

Normal.....just letting you know that it's pissedoffthat you let it sit that long....now go drive it, spank it, kiss it and put it away wet.....geez, the questions on this board....

LOL I couldn't agree more.

[911 heathen]

Sounds very much like valve stem seals.....ergo, a top end rebuild is required as long term 'preventative maintainence'.....all part and parcel of 3.2 ownership once they hit 80k miles plus...

I am booked in for a top end job in the coming weeks. Many owners would not bother with the job but since mine needs a new clutch, may as well spend the extra couple to 3 thousand and get it done so the car will be good for the rest of her days.....

[J P Stein]

My take:
Left to itself for a few weeks....2 in my case, the oil will drain back thru the scavenge side of the pump into the case....all of it, depending on the age of your oil pump. When it fills to the height of the bores, the oil trys to find its way to the combustion chamber. Again, depending on how tight your rings are and/or if the end gaps are all aligned & below the level of the oil in the case......poof...or just a bunch of smoke.
I think my after market pistons contribute to this.

If mine sits for 2 weeks or more, I crank it over for 30-40 sec to get some of the oil out of the case, then keep the revs down for a few minutes. Bad things can happen with a case full of oil.

Let your car sit for a month, them drain the sump (cold) & see how much oil you get. I've gotten 9 quarts.(I have 12 in the system)The feed line (914/6) is dry.

[Bob Goding]

JP Stein--I think you are on to it!---but---I cant see it being the scavenge
side as this returns to the top of the tank. more likely back thru the pressure pump which has the head of tank oil against it when its sitting.
My guess is that the variation in smoky startups might be the pump gear position when it stops as the oil will have to get across the pump to make its way into the oilways and into the case. This is my theory as to why the engine sometimes dumps oil on the ground---from the oil return tubes filling up then lots of oil in the covers by the exhaust valve spring area. then sucked down the valve guides on startup--Just the result of lots of thinking as to why my car does it too!

[J P Stein]

In the case (NPI)of mt 914, the scavenge side returns near the bottom of the tank.

Tho the feed line is below the engine oil cooler, oil travels to the pressure side of the of the pump (& one hopes all is sealed there) to the top (or close) of the engine..... to the engine thermostat, before it gets into the works. I'm not familiar enuff with the orientation of the oil level of the 911 tank vs the the height of the thermostat, but you may have a point. The other excuse is mine

[ianc]

Could it be that one of your oil rings just settled in a bad position and kind of congealed with the oil in a non optimal position?

I would definitely take it out and get it hot to see if the problem disappears. Aim for the swampy areas where the mosquitos hang.

ianc

[widebody911]

I just went thru the engine last year, and in fact I'm running gapless rings.

The oil seep theory makes sense. I've also done a lot of bouncing around with the car while it's been out of service, jumping up and down on the suspension a lot, breaking torsion bars and whatnot.

[mjshira]

Thom you are the man!

"a lot of bouncing around with the car while it's been out of service, jumping up and down on the suspension a lot, breaking torsion bars and whatnot"