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I have a G-body 911 with a 3.6L built motor out of a 964. Engine was newly rebuilt 5k miles ago. The car emits a lot of blue smoke for the first 2-3 minutes of driving until it is warm. Only does it after sitting for 24hrs. Brought it to the shop and tested compression and leak down both checked out perfectly. Also replaced all valve seals. Still smokes! What else could it be?
Mine does the same. After reading many threads on this subject it appears to be normal. Mine will do it after easy drives. Sometimes going to work I never get out of 3rd gear. It’s also 4 miles.
when I drive mine hard it hardly ever does it. My Indy says keep driving and enjoy.
I have a G-body 911 with a 3.6L built motor out of a 964. Engine was newly rebuilt 5k miles ago. The car emits a lot of blue smoke for the first 2-3 minutes of driving until it is warm. Only does it after sitting for 24hrs. Brought it to the shop and tested compression and leak down both checked out perfectly. Also replaced all valve seals. Still smokes! What else could it be?
Do you ever start the car and run it for less than a minute, such as to move it? Or start the car and let it idle to warm it up? Or let it idle for periods of time?
*Some* blue smoke is normal after sitting, but LOTS of blue smoke for several minutes is not normal IMO. I've owned quite a few of these cars and after 10 seconds or so, the smoke is gone (if it appears at all - have had multiple 964s, none smoked much at all unless it sat for a lot longer than 24 hours).
Only things that come to mind - are you parked on an incline? Do you drive like a Granny (short trips, low revs) or just to move it around a garage? If none of those are true, I disagree with the others given how much smoke you are seeing and for how long you are seeing it. Not saying you necessarily need to do anything about it, but I would probably also ask the question in the 964 forum since you're using the 3.6. That forum is more active and has quite a few really talented engine builders who frequent it.
My '85 with the 3,2 engine smoked also when cold when I used Mobil1 oil. Now I use Valvoline VR-1 and no smoke.
Well a just slightly visible puff, but nothing more.
About the aftermarket non return valves, my 911 sat in garage with normal oil fill for years and when I started it, no smoke.
I've noticed it before that you in the US have a tendency to solve non existing problems with additional parts.
Try with an other oil brand, it might solve your problem.
Have you verified that the oil level in the tank is correct for the 3,6 engine if you use the original dipstick?
My '85 with the 3,2 engine smoked also when cold when I used Mobil1 oil. Now I use Valvoline VR-1 and no smoke.
Well a just slightly visible puff, but nothing more.
About the aftermarket non return valves, my 911 sat in garage with normal oil fill for years and when I started it, no smoke.
I've noticed it before that you in the US have a tendency to solve non existing problems with additional parts.
Try with an other oil brand, it might solve your problem.
Have you verified that the oil level in the tank is correct for the 3,6 engine if you use the original dipstick?
My 78 I store for the winter so about 6 months and have almost no smoking on startup , but i do see it the next start after a good run anywhere, presumably because the hot oil right after a stop can seep back a little.
On another point, i have a friend who rebuilds air cooled cars and has seen where over long storage he has had situations where the oil has seeped back by the oil pump and into the crankcase and cylinders, and on starting the engine has bent rods due to the engine trying to compress the oil.
His recommendation after a long storage is to remove plugs and turn it over a few times first just in case..
I can see how the check valve would be cheap insurance against this rare yet very expensive incident.
So in short .. I don't think inflammatory statements about what people do with their cars and generalization of a country in general helps anyone .. it just comes off as arrogant posturing.
I store my car for the winter ('85 3.2), and I do not notice blue smoke on start up, I do get a small amount of white smoke (moisture) depending on temperature. I fully rebuilt the engine about ten years ago, but did not drive the car significantly before that, so I don't recall as it was before.
I have considered that Rothsport valve, and although I have not done it yet, I still might do... mainly due to Ice's point about the engine possibly "hydro-locking" on oil... Probably one of those things that are very rare, but fit the bill of low-risk/high-cost scenarios which I always try to avoid.
For the OP, there are two thoughts I might add:
1) As it is a built motor, your piston/ring/cylinder combination may just be one that has slightly higher cold clearance (and thus allows more cylinder oil seepage). I (very) vaguely recall something about some JE pistons being very slightly "looser" when cold because of thermal expansion coefficient of the alloy being used...
2) You mentioned that the valve seals were changed, do you know if the valve guides were? That could be a possible oil ingestion point that would not show up in leakdown or compression... (although I believe this issue would still present blue smoke when warm).
One way to more specifically evaluate valve guides is to aggressively engine brake to pull high vacuum in the intake and see if a pronounced amount of blue smoke is present. May want to have a spotter following in a separate car to watch closely.
So in short .. I don't think inflammatory statements about what people do with their cars and generalization of a country in general helps anyone .. it just comes off as arrogant posturing.
My writing was not meant to be inflammatory, but perhaps I'm looking things from a different angle. Seen a fair amount of "improved" parts that usually only improve the makers cashflow.
But one can do whatever he want to his car, I don't judge that, want to raise the question; do I or my car need this?
I'm not saying that for example the non-return valve is such, but is it necessary? I've had my '85 since 1995 and personally have never had any problems with the oil seeping into cylinders.
We have a hibernation period of several months here where the car just sit in garage, plenty of time for oli seepage. I do not start my car during hibernation.
If I passively have insulted someone, be assured that it was not my meaning and I apologize.
04-21-2024, 12:25 PM
Blue smoke when cold
