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M52 head? Coolant issues.

Posted: Sun Mar 02, 2025 8:33 pm
by Bobbobbington
Good evening all,
M52 b25 swapped e30. Originally thought I was having head gasket issues.
Compression test showed between 180 and 200 across all cylinders. Sniff test done 4 times and didn’t change colour at all.
Temp has been above half and system acts like it’s pressurising but the water in the rad was still cold.

Checked water pump and all good, have replaced stat to 80 degree. Have ordered the correct fan switch now as this was incorrect.

Where have people put there fan and temp switches in swapped e30s?

Thank you.

Re: M52 head? Coolant issues.

Posted: Mon Mar 03, 2025 10:29 pm
by Speedtouch
Welcome to the Zone! I would suggest looking at the E30 Wiki guide on these conversions:
https://www.e30zone.net/e30wiki/index.php?title=M5x#M52

Re: M52 head? Coolant issues.

Posted: Fri Mar 07, 2025 7:05 pm
by DanThe
The fan switch should be in the side of the rad, there is a provision for this on the right hand side tank about 1/4 of the way down.

If you have an original 90+ thermostat then the gauge will show above 1/2 way at running temp and it will take much longer to flow coolant to the radiator which is hopefully what you are experiencing

If you havnt got an auto fan loom I can highly recomend this https://bmconversions-uk.co.uk/product/ ... ensor-kit/

Featured in the below video, lots of other cooling system info in this video too