Help. 78 911SC. 2-3 qt oil overfill. major engine smoke.

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Help. 78 911SC. 2-3 qt oil overfill. major engine smoke.

Postby Brett 78 911SC on Sat Oct 16, 2004 7:24 pm

I'm new to 911 ownership as of a couple days ago, and I'm also an idiot. I didn't check the oil properly with the engine running like the manual states. I proceeded to add about 4 qts of oil to the tank. A couple minutes after startup, I got major white smoke from the exhaust. Shut it down and partially drained the tank, then restarted and let it idle for a couple minutes while blowing major smoke. I got scared and shut it off after pulling it quickly back into my garage. I'm guessing that I overfilled the tank by 2-3 quarts. How do I proceed in this scenario on a 911SC? Just drive and the smoke should clear up eventually as the oil gets burned out of the intake? Or get thee immediately to a shop to have the intake dismantled and cleaned of oil? Or what else. What have I done? Any other possibilities of ancillary damage like the catalytic converters?

Thanks,
Brett
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Postby Steve Grosekemper on Sat Oct 16, 2004 8:08 pm

Brett,
First of all you are not an idiot, just guilty of not reading the owners manual first. This is the #1 mistake made by a new 911 owners.

What happened is you over filled the tank and oil was forced into the breather and made its way to the top of the sensor plate and into the intake.

The easy solution is to tow it to a Porsche shop and have them clean out the intake, drain the oil and get you going again. This smoke is very bad for the cat converter. The least amount of time the car runs in this condition the better.

If you want to tackle this yourself try this:
-empty the oil tank
-remove the air filter housing (clean the airbox)
-remove the intake boot (clean sensor plate and throttle plate)
-clean the oil hose from the boot to the tank.
-fill the oil tank with 3 qts. of oil
-start the engine and let it run. As the smoke clears rev the engine, and you will get more smoke. after the engine is warm 180' top off the oil.

Remember only check the oil warm, idling, on level ground.

After this go drive that car and use the right pedal vigorously. The intake needs to see heavy airflow to pull all that oil through the system. It will smoke some more.

It is a long process and will most likely anger your neighbors. if that is the case, tow it in to your mechanic.

Trust me you will never do this again and by sharing your experience here your have saved another new 911 owner the same fate.
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Thanks Steve.

Postby Brett 78 911SC on Sun Oct 17, 2004 8:41 pm

I cleaned a large puddle of oil from the air filter box. I didn't feel comfortable pulling out the rest of the intake, yet. But, I took it for a drive. It smoked like hell for the first mile or so, then cleared up. I figure I'll give the intake a good cleaning when I get more used to working on this engine.

Thanks for setting me at ease.

Brett
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Postby richard on Sun Oct 17, 2004 9:43 pm

Additionally, if you fill to the max line, you will have some of the same symptoms, just not as severe. Don't go over half way. As me how I know.
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What's the volume difference between the min and max marks?

Postby Brett 78 911SC on Mon Oct 18, 2004 9:39 am

Is it one quart min to max? 2 quarts? 1/2 quart? I was filling from a 5 quart bottle so I couldn't tell how much I was adding between level checks.

I filled to about half way between like you say after completing the oil change that I had started out to do in the first place.

Brett
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Postby Steve Grosekemper on Mon Oct 18, 2004 11:46 am

The difference is 1.85 quarts between the top and bottom marks so if it doesn't show on the stick only add 1 quart at a time. I like 1/2-3/4 on the stick as a higher level will tend to consume more oil even if no smoke is detected.

Remember if you run higher oil temperatures 200-210 the level will be higher, and you should adjust for that.
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