M50/M52 - gas powered fog machine

[BennyM]

Hey guys, I'm posting an E36 question here because I trust your opinion and experience with these M50-based engines. My sister's '98 323is runs really rough and shoots steam out the tailpipes like crazy. The oil is milky and it overheats easily when not on the freeway. Coolant flow also seems slower somehow than what I'm used to seeing. So, I and several other mechanically inclined people concluded the obvious head gasket (probably caused by a bad waterpump/T-stat), but here's the tricky part: The compression test shows strong compression in all cylinders, higher than the specs in the Bentley in fact. That said, the numbers vary quite a bit between cylinders. We wanted to cover all the bases before ripping into the engine. Is there any other way that coolant could get into the cylinders and oil of the engine besides a head gasket? Maybe that sounds like a rookie question, but I wanted to make sure.

[whiskychaser]

A 'sniffer test' on the coolant isnt foolproof but it should tell you if exhaust gases are getting into the coolant. That would normally indicate the HG is gone. But the head may also be cracked. After rebuilding my engine the first time, I had great compressions. But the coolant was milky and I also had an external leak. Somehow the timing chain cover wasnt seated correctly. It carries coolant and in my case was spewing it out and dropping it into the sump as well. So I had great compressions but milky coolant.
Unlikely but you did ask for possibles :-) The initial cause of the overheating may be the fan clutch as it stays cool at speed. Cant locate Bentleys but IMHO compressions should be within about 5% of each other.

[genphreak]

Gasket or heed is gone. Most likely the gasket.

Do not use the car. Change the gasket promptly, and verify the head is not cracked or warped before putting it back on. If you have not done it before, don't try on your BMW, it is not the easiest to get right the first time, though much info is available online- the problem is that it is a big job and it isn't very easy unless you have done such things before. You do one wrong thing and its all toast- and costs a lot to start over (buy new gasket kit, etc.). Good luck.

[BennyM]

So, it turns out that the head gasket was fine. There was a small crack in the head. A local shop cleaned the head and pinned the crack. They also said the head was not warped. The engine is mostly back together now and all cylinders have good compression.

[shogun]

for those who do not know pinning or stitching

Metal Stitching (http://www.locknstitch.com/Metal_Stitching.htm)

Cold repair, also known as pinning or stitching, has been around the automotive world for quite some time
Repairing Cracks in Cast Iron Cylinder Heads and Engine Blocks (http://www.aa1car.com/library/ar497c.htm)

[christopherh]

You need not use the vehicle on a regular basis. Change the gasket regularly before putting it back on. The fog machines are really not working as you expect.

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fog machine (http://www.froggysfog.com/category/20-machines.10-fog/)

[genphreak]

You need not use the vehicle on a regular basis. Change the gasket regularly before putting it back on. The fog machines are really not working as you expect.

Ugh. Don't follow the link: Don't feed the troll.

Even one who is contextually correct and is right about not having to drive one's car on a daily basis!