Puff of smoke on startup

[kavadarci]

Hi my car engine has puff of smoke on startup once ina while and typically after sitting for more than a day.

It doesn’t do it always and I don’t know what is the pattern.

Any thoughts?
Is this bad?

I’ve read somewhere that there is a valve that can be installed at the engine oil hose as some oil goes back in the crank from the oil tank.
Mthank you

[john walker's workshop]

They did it when they were new.

[Jack Stands]

One of mine could be fogging for mosquitos if it’s been sitting for a few weeks. But once it clears, it runs great and doesn’t burn excessive oil. It’s funny as my other cars aren’t as Smokey.

[gazzerr]

Normal. I have seen those check valves too.

[Canada Kev]

Mine does it for the first few starts in the spring after winter hibernation. I think that in my case it's likely the fuel stabilizer I've been adding for winter storage. After I get that winter tank used up and filled with fresh gas, it doesn't happen any longer. It never did it before, but the last two springs it has, which coincides with the current bottle of Stabil I have. It's almost gone so we'll see next April...

I know this probably doesn't help the OP, but it might be a bit of info for future reference for others.

[tirwin]

Yes, park on just the right incline and you’ll get a big puff. Jeff Gamroth (Rothsport Racing) makes a check valve that goes in the S tube from the oil cooler to the tank. I believe it’s modeled after the same design used in 964’s (I think?). Pelican sells them. Search for oil inlet check valve.

It doesn’t hurt anything. Except I fumigated some people at a car show once. I called it a Porsche baptism.

[SCadaddle]

[Bill Douglas]

I thought "Holly smoke" one day. The car went br br br brrr brrr brrr brrruuuummmp brummmm and clouds came out of it. I thought something had broken but I think it was just a weird occurrence of a valve not completely closed and the angle of the road, and a LOT of oil draining into a cylinder.

[kavadarci]

Thank you guys.

[Quickstep192]

As the risk of demonstrating my lack of knowledge...

Just what path does the oil take to find its way into the cylinders?

I'm guessing through the valve guides and then through an open valve?

[manbridge 74]

Puff is normal, harms nothing and extra oil might prevent more wear since cold starts are where most friction is. Check valve? Seriously?

[wreckah]

Originally Posted by Quickstep192

Just what path does the oil take to find its way into the cylinders?

i think: flat six = cylinders horizontal...oil gently seeps past rings (from crankcase into cylinder)

the puff is bigger the hotter you turn off the engine. So when you have just seriously flogged it, park it up, and then it will have a nice cloud of smoke the next day

[Topocalm]

I have the same issue on my Turbo. Not always, and quite a lot of smoke at first start. To the point that I had an enraged neighbour telling me I was poisoning his children in the underground garage.... I'll try the 'Porsche baptism' line next time he pipes up..

[Quickstep192]

Originally Posted by wreckah

i think: flat six = cylinders horizontal...oil gently seeps past rings (from crankcase into cylinder)

the puff is bigger the hotter you turn off the engine. So when you have just seriously flogged it, park it up, and then it will have a nice cloud of smoke the next day

OK, let me have another run at displaying my lack of knowledge...

I thought most of the oil was in the tank. No?

[theiceman]

this is the reason I don't back my car into the garage , as the garage is attached to the house. The yelling from inside the house usually lasts longer than the smoke so I decided to park in front way.

[SCadaddle]

If, after driving the car, you let it idle for a couple of minutes to let the scavenge side of the oil pump do it's job to scavenge the oil in the engine case before shutting it down, you might be amazed at the lack of the puff of smoke on the next start-up.

[nene]

I keep reading about the "smoking gun". Back in my high-school day (circa 1986) when I had my first 1975 911S with approximately 86k miles, which I drove for nearly 5 years, I do not recall once when it ever smoked.

[tirwin]

My experience is that there are at least 2 separate things that can cause excessive smoke on startup.

Oil can migrate from the tank back to the crankcase. My experience was parking on an incline -- pretty sure it was nose downhill with left side lower than right. In this case, the oil level in the tank runs down the S tube back towards the oil cooler. This is what the Rothsport inlet check valve is designed to prevent from happening. It basically only lets the oil flow one way. Any positive pressure and the check valve opens, allowing oil to flow.

I found the thread where Jeff Gamroth commented. He said it's basically the same design as what's used on the 996/997 turbos.

The other case is when cold control pressure on CIS cars is too low. In that case you end up dumping excessive fuel in a cold start.

[Superman]

Normal. It is part of the engine design.

If you want to know whether oil is getting past the valve guides and seals, one way of evaluating is to cruise down a steep hill for a distance with gravity as your only power, foot OFF the gas, and then look in the rear view mirror when you finally put your foot back on the gas. If oil has leaked past the seals, then you will see blue smoke.

But yeah....smoke on start up------> Normal.

[911SauCy]

I GENUINELY laughed out loud reading this thread title...