M42 Thermostat

[dr.gonzo]

I've completely overhauled the cooling system and the current thermostat keeps the car close to the 3/4 mark no matter the time of day or temperature. I'm not sure what size thermostat is needed but I wanted one that would be significantly cooler than stock to handle AZ summers.

I also am not sure where to look for a lower temperature AUX fan switch.

Thanks

[jlevie]

Something isn't right. Either the gauge is lying, or the engine is running hot. A check of the temperature of the cylinder head when the gauge is reading 3/4 will tell where to look.

Did your "complete overhaul" include the radiator, expansion tank, cap, fan clutch, thermostat (88C), water pump, and all hoses?

[dr.gonzo]

Something isn't right. Either the gauge is lying, or the engine is running hot. A check of the temperature of the cylinder head when the gauge is reading 3/4 will tell where to look.

Did your "complete overhaul" include the radiator, expansion tank, cap, fan clutch, thermostat (88C), water pump, and all hoses?

I have replaced:
Aux fan, Fan clutch, Radiator, waterpump, and thermostat. I had the work done by Bavarian Workshop in West Hills, CA (Very reputable shop). They originally had installed a bad thermostat and I have a feeling that they replaced the bad one with a higher temp one because even with the heater on, driving on the highway, at night, it stays at 3/4s and wont go past it. I'm considering removing the thermostat later (Or drilling a couple extra holes to help the flow) later today

[vpilarrt]

Fan clutch and/or bleed.

[jlevie]

The best course of action would be to use an IR thermometer to find out how hot the engine is really running. But if you want to blindly throw parts at the problem while hoping for a favorable outcome, get a new OE 88C thermostat and put it in. Then make sure you fully bleed the cooling system.

[dr.gonzo]

The best course of action would be to use an IR thermometer to find out how hot the engine is really running. But if you want to blindly throw parts at the problem while hoping for a favorable outcome, get a new OE 88C thermostat and put it in. Then make sure you fully bleed the cooling system.

Isn't it obviously a thermostat if it is maintaining the car at a specific temperature no matter what? The thermostat is regulating the cars temperature at 3/4

[jlevie]

Not necessarily. It could be that there is a fault in the gauge, it's sensor, or the wiring. Or it could be that the wrong (or faulty) thermostat is installed. The temperature of the head will tell which it is.

[dr.gonzo]

I removed the thermostat, drilled six holes in it (a little overboard) and put it back in. Now the car isn't coming up to proper operating temperature. Where can I get an 80C thermostat for an m42?

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[Nick_S]

Anywhere should have an 80C thermostat. I got mine from Pelican Parts. Mine was reading 3/4 mark before I bled the system even with an 80C. After that, right in between 1/4 and 1/2

[jlevie]

The M42 engine wants the stock 88C thermostat. Obviously you could get it from a dealer, but there are many other sources (local auto parts houses or on-line retailers).

[bmwman91]

Yeah, the 88C thermostat is the correct part. If you are getting hotter than that, there is something else wrong. Are you installing it backwards? A number of people make that mistake.

[dr.gonzo]

Would this thermostat work? http://www.pelicanparts.com/cgi-bin/...2531%2529%2520

[roguetoaster]

Would this thermostat work? http://www.pelicanparts.com/cgi-bin/...2531%2529%2520

It might, but you really want the 88 degree M42 thermostat, P/N 11-53-7-511-580. Whichever brand you want should be fine, but make sure it includes the sealing ring.

Link on Pelican

[dr.gonzo]

It might, but you really want the 88 degree M42 thermostat, P/N 11-53-7-511-580. Whichever brand you want should be fine, but make sure it includes the sealing ring.

Link on Pelican

I want a a 80c one only because of the summers here

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[kwill22]

88 will be fine. Mine doesn't go above the half mark in summer. Granted your summers might be a tad hotter than mine I'm not sure but if your cooling system is running as it should you'll be fine.