Weird Overheating / Oil Leak Issue

[JonCr]

I’ve got a situation with my 1999 323is that has me stumped and I’m hoping someone on here can make sense of it. I apologize for the wordy post, but I want to get all the details out there.

My e36 was in great condition with no oil drips in the driveway and no warning lights on the dash - a good running car. Once colder weather hit, I noticed that the thermostat was stuck open and it wasn’t reaching temperature. I replaced the thermostat, bled it, and all seemed good. My son drove it for a few days with no issues. About mid-week, he was driving it and the low coolant light went on. Shortly after that, it overheated and he pulled over. Once it cooled down that night, we drove it home. He said it smoked while it overheated, so I immediately assumed head gasket.

At home, I checked it over and noticed it was a quart low on oil, which was odd because I had just changed it days before. I got under the car and immediately noticed oil EVERYWHERE. It was all over the bottom of the car. I started wondering if the smoke was oil getting on the exhaust. I assumed the overheating had caused a major oil leak to spring - big enough to pour out a quart of oil.

I thought maybe the expansion tank was leaking (though I think I overfilled it and it was just leaking out the bleeder down the neck). I replaced the expansion tank, filled it up, bled it well (while jacked up), and topped off the oil. I borrowed a block tester from the auto parts store and tested for a blown head gasket. It was negative. Tested it multiple times. No overheating and no coolant leaks.

Here’s where the weird part is. I let it idle in the garage for about 30 minutes while bleeding it. No oil leaks. I then took it on a 10 mile drive. No overheating and no oil leaks. I then took it on a 20 mile drive at 70 mph on the highway. Got home and let it idle in the garage while I laid on the ground. No oil leaks - not a drop. I’ll let it sit overnight to see if there are any drops in the morning, but I don’t understand how it could leak a quart in a matter of seconds and then not at all now.

Is it possible to blow oil out of a vent or something when the car overheats? Any scenario where it leaks like crazy when overheated and then not at all afterward? Thanks. Jon

[JonCr]

Update: The car sat all night after the highway test drive and not one drop of oil on the garage floor this morning. Still confused how it could leak so bad during the overheat episode and then not leak at all afterward.

[spyderg0d]

Might be stupid question but how did your kid know it was an overheat? Did he see the guage hit red? Or was it just because it started smoking and stuttering and such?
I know bad cvv can freeze, causing oil to be thrown into the intake, making so much smoke it is rediculoues. Can burn guarts in matters of minutes.

[JonCr]

Might be stupid question but how did your kid know it was an overheat? Did he see the guage hit red? Or was it just because it started smoking and stuttering and such?
I know bad cvv can freeze, causing oil to be thrown into the intake, making so much smoke it is rediculoues. Can burn guarts in matters of minutes.

Not a stupid question - he saw the gauge go into the red. I thought about the ccv for the smoke, but I don’t think that explains the oil on the bottom of the car - unless maybe it’s possible for the ccv to leak out?

[Eric93se]

Or the head got so freaking hot that the HG puked oil.

After letting the car sit for a long time (ie over night) I would pull all the plugs and look in there for coolant. While the plugs are out I would do a compression test. Be sure to read up on how to do it right.

[Eric93se]

Also just for future reference (when you get your car fixed) you can't drive these cars after they have overheated, letting it cool down and then driving it is not ok for these engines. The head cracks and warps when it overheats. It's never ok to drive it after it over heats, you have to call a tow or AAA. Even if you don't have AAA, put their 800 number in your phone and you can buy AAA service and then you can request a tow right after that.