garrity928

I have a 1990 911C4 that a freind of mine drove until it warmed up and stopped the car to run an errand. He came back out and started it up and drove about one mile and the engine stated blowing burning oil like the spy hunter car. It would not turn over after he shut it down. I later pulled the plugs and found several cylinders completely full with oil. I suspect that he overfilled it earlier that day and the oil when it warmed up and expanded, went out the breater hole on the top of the case and into the intake. The intake was very wet with oil. When I pulled the exhaust it was also filled with oil. The car never got overheated and he shut it off prior to a fire or locking it up. Any suggestions as to the actual problem would be apprciated. The car does have good compression on all cylinders too. about 170 across the board.

Thanks,

Garrity

Bill Wagner

I saw something similar happen at a non-Porsche dealership once. A salesman decided he was going to "service" the car by topping off all the fluids....oil included. He did this with the engine cold and not running. I'm sure he meant well, but after that the car was next to impossible to start, and in this case, he actually overfilled it with so much oil that it was leaking out of the car at a rate of about 10 drops/second. Not a pretty site!

Dial 911

Grossly overfilled!
This also happened on one of our club runs with a new owner, yet unfamiliar with the 911 oil level routine. Have your friend read his owners manual.

Oil is not compressible. If the cylinders were really full, and you tried to turn it over, you risk bending something. It's called hydro-locking. Hopefully your friend was lucky. If not done so already, drain the oil down to the correct level ASAP.

You will also find oil throughout the air filter housing, and the intake runners and air flow monitor. Not good, and should be cleaned out before it gums up everything.

garrity928

I agree with reading the owners manual and have explained this to him on at least two other occassions. I pulled the engine out and have it on a stand and it appears that after all the oil was drained out that the engine has good compression. The real concern that I have right now considering that the engine was unable to be turned over by hand until the oil was drained, was whether or not there will be any future problems if I reinstalled it. It is possible that a rod bent and I wouldn't know it until it breaks!

So it is possible that the oil expands enough that it comes out of that vent hole on the top of the case and gets siphoned into the intake. All the intake is oily and I agree about that needing to be cleaned. Any further help is appreciated.

Thanks,

Garrity

Randall G.

Hi Garrity,

Sounds like you were extremely unlucky, or your friend reallly over-filled the oil. 911 owners seem to be over-filling their oil "all the time," and the worst thing that happens is a lot of blue smoke and oil puking all over the engine. I personally have never heard of a car that wouldn't run as a result of oil over-fill, but, hey, I'm no mechanic or the ultimate authority on over-filling

FWIW, I believe a lot of 911 owners that actually know how to check their oil level still wind up having (mild?) over-fill events. For example, they'll have the car warmed up, and adjust oil level to near (maybe a little over?) the upper dipstick notch. Later, they'll be stuck in traffic on a hot day, the oil gets especially hot, expands and overflows. Because of this hazard, many 911 owners (including myself) try to keep their oil in the lower half of the acceptable band (i.e., closer to the lower notch than the upper notch).

Dial 911 ... I've never heard of hydro-locking as a result of over-filling the oil Have you actually seen an engine that has been damaged this way? Curious ...

Bill, I love your story about the salesman that wanted to top off all the fluids on a 911. I wonder how many quarts of oil he had to add to get a reading on the dipstick with the engine cold and not running??

ked

Get a $10K damage security deposit from this "friend" whenever you loan him your Porsche, wherein he fails to heed your repeated instructions or read the manual.

Personally, I think a great deal of damage to high performance cars is done by "friends" - that's why I don't let them drive my cars. That way, I have both functional cars and understanding friends.

Roland Kunz

Hello

Overfilling start engine leaks. The oil is ventet into the mainfold and will get in the combustion chamber. Engine runs rough while the oil is burned. Burned oil kills the catalyc convertor.

Grüsse

Dial 911

No, Randall, I have never heard of anyone hydro-locking a motor with oil. The poor 911 in question must have been drowning in the stuff! But...I have experience of several cases of engines that were hydro-locked with gasoline.
Leaking injectors, defective carbs, hay-wire fuel pumps, etc.

Randall G.

Wow ... my intuition tells me the non-combusted gasoline would blow by the rings or someplace before permanent damage occurred ... but, my intuition is not always right. I mean, it has to be a very good seal to hold enough pressure to cause physical damage. Then again, I don't know what sort of pressure is associated with combustion, but the rings normally contain the combustion gases in this case Hmmmm.

Call 911 ... or any other person that understands the seals/pressures inside a gasoline engine better than myself. Any thoughts? Thanks ...