View Full Version : How far does the thermostat open if working correctly?

05-29-2006, 06:07 PM
Hi guys,

My E30 is overheating at 5/8-3/4 temp gauge regardless of idle or at speed. I swapped out my fan clutch (just in case) but at full highway speeds it still is overheating, and from what I understand the fan clutch doesn't do much at those speeds anyway.

So I think it's the thermostat. I took it out and put it in boiling water, and the water moves through it after being put in there, but I can't really see it open. Is it supposed to open up a lot (like an .5-1inch or more?) or just a little, when functioning normally?

Buying one at the dealership tomorrow when it opens, but just wondering if the problem is something else.

05-29-2006, 06:26 PM
You should be able to definately notice a difference once it opens. It's a simple design. Basically once it heats up enough to melt the waxy stuff inside it the force of the spring opens it up.

05-30-2006, 02:33 PM
I haven't tested a thermostat in boiling water, but it should be obvious when its open, like a 1/4 inch at least.

05-30-2006, 09:45 PM
Well I picked up a new one from the dealership. Honestly the difference b/w the new one and the old one wasn't that great when dumped into boiling water. The new one seemed to be extended slightly more but it was kinda hard to tell. Just more a curiosity thing than anything.

Anyway, stuck the thing in and spent like 12 hours on the car doing random fixups but it looks like it no longer (fingers crossed) overheats with the new thermostat and coolant. ABS now works, IS spoiler installed, summer Yokos on alternate weaves mounted. But the auxiliary fan is really really broken now. Oh well. 4 positives, one minus. I'll take it :)

P.S. The local dealership, who should remain anonymous, has a completely useless parts department. Gave me an oil pan washer instead of a coolant drain plug washer after telling them to make sure not to give me an oil pan washer - I pointed it out to them on the spot when they gave it to me, so they gave me another washer that was also incorrect. gave up and reused the old one.

05-30-2006, 09:48 PM
P.S. The local dealership, who should remain anonymous, has a completely useless parts department. Gave me an oil washer, then another incorrect washer right after I pointed it out to them on the spot after that for my coolant drain plug but I didn't know then and forgot to bring my plug. gave up and reused the old one.

I feel your pain. My local parts department doesn't seem to realize that BMW had cars made in the 80's - lol

They do a good job - but everything is expensive, they don't know what BMWCCA stands for, and almost EVERY item I need has to ordered in - and that takes 7 business days - LAAME

05-30-2006, 09:54 PM
The dealerships I go to in Boston are much better.. Herb Chambers has pretty good pricing for BMWCCA members and Peabody BMW is more expensive but their people (last time I went has been a while though) seemed relatively knowledgable.

The ironic thing is that the one I went today claimed to be "5th largest in parts inventory in the Northeast" but didn't carry a radiator drain plug... and I found one in my garage (but after everything was put back together).