M20 UNDERheating?

[roznic]

Same thing with mine, heats up to about 62-65 according to the pic. Interesting fact, that I just did s52 swap and temp gauge does same thing as with good ol m20?!

[JinormusJ]

You can test your t-stat but placing it in a pot and heating it on the stove. Use a thermometer to verify the temp that it opens at.

I did this with my old one and after comparing pictures and seeing it open at 80°C myself, I found that it's the Thermostat I always usually use made by Vernet.

My old one seems to be working fine.. Except; only the center spring moved when it openned. Are both springs/flaps supposed to move or is the smaller spring pressure activated versus temp activated?

At this point, I'm thinking of taking the new Wahler out and putting this Vernet one back in

[TobyB]

It's your t- stat. Change it back, and I'll bet you're good to go.

And oddly, I've had them change behavior when they dried out. They SHOULDN'T,
but especially on older ones, they don't seem to like getting dry. Rubber seals?

And yes, I've had trouble with Wahlers, Vernets, Stants, and genero- zone ones, too.
The wax inside is a pretty cool trick- and apparently, not trivial to get right...

hth

t

[CorvallisBMW]

It's not uncommon for brand new t-stats to be defective, no matter the manufacturer. Best to test+verify.

[JinormusJ]

It's your t- stat. Change it back, and I'll bet you're good to go

Changed it back to my old one just this morning: heating at 7/16ths, like it should. I'm a happy guy; it only took two extra jugs of BMW coolant though LOL
But I managed to save and filter most of it, so I have 3 jugs of 50/50 on tap now

I seem to have the best luck with Vernet though; out of my eight or so timing belt changes, that one was never let me down. This is the only one I've ever had problems with, and it was the more expensive Wahler one. Go figure

If it ain't broke, don't fix it: certainly applies here

It's not uncommon for brand new t-stats to be defective, no matter the manufacturer. Best to test+verify.

I pulled out the old thermostat and verified it and the Wahler one opens way too early, like around 60°C, whereas my old Vernet one opens around 80°C like it should

Called up the shop I bought it from and they said the best they can do is a warrantee exchange even though I don't need a Thermo anymore... Whatevs

[CorvallisBMW]

I pulled out the old thermostat and verified it and the Wahler one opens way too early, like around 60°C, whereas my old Vernet one opens around 80°C like it should

Glad you found the culprit.

[packratbimmer]

I have found that the Wahler 88 degree stat behaves closer to the 80 degree spec. The B/T (Behr-Thomson) 80 degree performs better to factory specs in my experience. I run the Wahler 88 in the winter in Maine so the car heats up a bit faster and stays at the 12 o'clock mark.