white smoke coming out of the exhaust and rough idle

[Hoang928]

my 1990 964 is blowing white smoke from the tailpipe (i mean it is a lot) and the car feels very rough while and it dies on me while driving .... is it because i put too much oil i don't know i just change the hose around the oil thermostat (sorry im new to this )

[Don Plumley]

It could be due to oil spilling into the air filter (from an overfill).

What is the oil level? I assume you are checking it with car at operating temp, on level ground, with engine running?

[CPBMD]

After the car is warmed up (temp guage at about 8-9 O'clock Position), what does the oil level guage read? Does the needle go into the top solid white bar on the guage? According to the owners manual the oil guage should be about horzontal. I slightly overfilled my oil with the guage just under the white bar and I have had no problems Yet!. Also check the dip stick with the engine warmed , running on a flat surface. The level should be between the 2 markers.

Con

[ischmitz]

Overfilling the oil is a pretty comon mistake on a 911. Other than a conventional wet-sump engine the oil level on a 911 is checked with the engine idling at operating temperature on level ground. If you used the dipstick on a cold engine that wasn't running you could have easily put 2 - 4 quarts too much oil in. Once the engine warms up the oil expands and areates and that causes the oil tank to internally overflow. Oil will be sucked into the intake and cause white smoke, poor running, knocking, etc.

Use the dipstick and check how much oil is in there. If you have overfilled it you need to syphon oil out of the oil tank or drain some from the engine sump. It will be messy but required.

Good luck,
Ingo

[CPBMD]

HI Ingo
How do you siphon oil out of the tank? Do you just stick the tube down the place where you put the oil in? I guess you need to get a siphon with a bulb on it so you don't end up inhaling oil.
Thanks Cons
Where is the engine sump?

[ischmitz]

How much oil did you add?

And yes - a syphon with a ball would be the easiest way to do it. Or you drive to a Jiffy Lube (or similar shop) and ask them if they can stick their vacuum oil pump in there and get about 4 quarts out of there.

To get to the engine sump on a stock 964 you need to take the undertray off. That is a lot more work. The oil tank also has a drain plug but if you open it you will empty the entire tank and create a mess.

Ingo