Cheap/broken bolt in thermstat cover '89 525 BEWARE!

[Gene in NC]

Thermostat bolts are 3.2. Break one for a helluva mess. Remove intake manifiold to replace thermostat housing for about $60 parts cost.

Or drill out and easy out the broken bolt. Oh yeah! I've done more than a few broken bolts. This was not possible. Can't get any heat to it.

Solution: Drilled out the top left bolt and formed nut that would fit behind the flange on the thermo housing. REplaced the other two with 8.8 stainless.

Net: If you have a chance get the stainless in early.

[Blitzkrieg Bob]

Seems they like to rust into place.

I had trouble removing mine, but I just replaced them with some anti seize stuff

[Mitch90535im]

I feel your pain.

I'm over a week into trying to get two broken water pump bolts out of my block. One still has about 3/4" of the shaft exposed and the other is broken flush with the block. They're so small in diameter that a bolt extractor is almost impossible and the one with the shaft still exposed I can't seem to find anything to grip it to make it turn, but then it'll probably break flush with the block too.

[genphreak]

Pentron or the like, left to set. Heated up with blow torch, then left to set. Do this a few times that the oxidesed zinc will break free and allow you to coax it out. Try freezing with between cycles for maximum effect. Salt and iron is the usual cuplrit, that and BMW's unique formualtion of zinc that is designed to frustrate unwary wrenchers beyond distraction.

[Gene in NC]

No heat, no luck. My impression is that solvent applied after heat to quench heat in the bolt breaks the oxidation.

Other problem is BMW uses very fine thread. How much precision is need to contain 15psi in the cooling system. Just broke a screw on the side of the throttle body on '87 325is. Same crap and common failure of the gasket.

[genphreak]

Hmm.. I've done it many times, never ever broken a bolt on the cooling system, only ythe exhaust manifolds- and that is all angle and extreme heat at fault. (That and the zinc oxidation lock that happens on the head studs ver commonly). I don't even use penetrant most times- and I'm working on '85-90 models mostly. We have no salt on the roads in Aus, I think it must be that also.

I always use thread lube when I put them back together, makes going in again far easier to contemplate!