M50 overheating & head cracking

[hoveringuy]

So I know that all the M50's with cracked heads have overheated, but does the head always crack when the motor overheats? How many M50's have overheated with no resulting damage to the head or head gasket?

Reason I ask is that the history of my yet-to-be installed M50 includes an episode of overheating that included a broken radiator neck/failed water pump. I don't know exactly how much it overheated.

The car ran fine for 5 months after it was repaired until it wrecked and I didn't see any evidence of coolant in the oil.

Do I have anything to worry about? (besides taxes, exams and the usual stuff...)

Hoveringuy

[BDSax]

if it ran fine afterwords then you may be ok. maybe just the head gasket failed. if i was you i would take the head off and have it milled just incase.

[hoveringuy]

The motor will be on the stand for the next 4 weeks so it would be a lot easier to do it now, for sure. I just don't have the tools and I'm looking for "my M50 overheated but it's fine" stories.

I need a happy ending.

Here or Thailand, either way.

[matt]

Hmm... tough situation. If it ran well when you pulled it (and you KNOW it ran well... lying sellers don't count) then I would just put it back in.

Overheating is not a huge deal if the motor still runs well, but it will eventually result in a blown headgasket and possibly a cracked head.

[hoveringuy]

Yeah, I've talked to the 2 previous owners.

Owner #1, before them, had the car and "thought he blew a head gasket". Traded the car in. I interpret that to mean that it overheated and he really didn't know why.

Owner #2 saw a good deal, replaced the composite water pump which was in sorry shape and the radiator which had a broken neck. Drove it for 3-4 months with "no problems". Changed the oil twice and never saw coolant in the oil. He's got no reason to lie to me.

Owner #3 bought the car and wrecked it after a month. He also says it ran great and didn't have any problems with it. (until it hydroplaned)

Owner #4 (me) thinks the head gasket may eventually need to be replaced but doesn't have the proper tools for the cams. The head gasket can still be replaced later with the motor in the car but it would be easier now. May also just swap in an S50/S52 later this year depending on how things go.

I know they M50's frequently over-heated because of the water pump and/or radiator, but who has seen it happen with no ill consequences??

[matt]

I can think of a ton of cars that have been overheated and not blown up right away. That doesn't mean there are no ill consequences.

[hoveringuy]

I'm stubborn and I can't leave something undone, so I started pulling it apart until my wife gave me the evil eyeball.

I'll have pics when I get head off in a day or two.

[Teaguer]

Well at least you'll know it has fresh HG now .
Down side is that you'll probably start wanting to replace things left and right since you are in there .

Oh and I drove my NV M50 E34 for 2 years with a leaky HG in Texas weather . ;)

[hoveringuy]

Pulling the head is like waiting to see if you've lost the lottery...

Mine wasn't as bad (or as good) as I thought. No obvious damage but lots and lots of carbon. Piles of it!

What's the preferred way to clean that mess up?

[87-325ic]

some good carb cleaner, or seafoam, and a ton of lint free rags. not to mention plenty of time scrubbin.

[matt]

One word: Roloc

[hoveringuy]

some good carb cleaner, or seafoam, and a ton of lint free rags. not to mention plenty of time scrubbin.

Yeah, like lint would hurt it anymore than 5 grams of loose carbon per cylinder!

[mazur]

My belt once jumped off somehow and didn't realize it till the temp had almost reached the red region when I shut her off. 10k+ hard miles later, no problems.

[hoveringuy]

Cam timing tool. The way BMW could have done it (cheap!)

[matt]

Wow... I wouldn't trust that.

The timing tools are not expensive. And they're worth it.