Last resort please help with overheating

[PNWM42]

Alright I've done everything I can think of on my 1991 318is, I've replaced all of my drive belts, my water pump, my thermostat 3 times, some of the cooling system hoses, the clutch fan, and the last thing is the water coolant plastic pipe that runs from the block to the cooling system. The only thin I haven't done is the mess under the intake and the damn radiator. All four cylinder compression are around 180-190. Please help I really need to get my car back on the road!!

[monty23psk]

Did it start overheating before you did all that? What was happening that made you do all that work?

[1998ccc]

Bled properly with heat on?  Make sure the grove in the thermostat housing is clear so it will bleed easier.

Use a laser thermometer / thermo attachment to your DVOM to check for accurate gauge readings or cool spots in the radiator.

Any chance you added stop leak recently...they will stop up a rad.

Good luck.

[PNWM42]

I  was doing 60 on the highway for about 15-20 minutes and I heard a pop which was all three of my drive belts snapping and the water coolant pipe that runs from the engine block to the cooling system all the hose connectors snapped at the plastic ends on all four ends. No stop leak has been added. And I've had the shop in my town do the thermostat replacement.

[monty23psk]

After the pop and the belts coming loose. How long did you drive it? What did the temp needle in the gauge do? How hight did it go? Loose belts popping off is common, has happened 3 times to me. Once it was a long slow drive to get it home to prevent needle to get to 3/4.

[DesktopDave]

Compression sounds good, I'd trust the head & HG. Did you try out a cooling system pressure check? HF sells a cheap ~$90 pressure tester with a BMW fitting, less with coupon or on sale. Really helped me out with overheating, ended up being a heater core AND a pinhole leak in the control valve.

You didn't use the URO part for the plastic coolant manifold, did you? Mine cracked just like yours did. I replaced it with a Uro part that didn't fit, then replaced it again with the OEM BMW Part instead.

You're using the correct alu thermostat housing with a paper gasket, proper o-ring, and you checked the bleed passage in the casting, right? Stock temp thermostat? I also use 1/2 bottle or WaterWetter and dilute my coolant down to 33:66 with distilled water, tremendously helps with bleeding and hasn't frozen up on me yet.

[mmkale]

the temp gauge can't be trusted. confirm overheating with a thermal gun gismo witn digital readout.

[jrobie79]

the temp gauge can't be trusted. confirm overheating with a thermal gun gismo witn digital readout.

where should the gun be pointed to get an accurate reading? My gauge barely cracks 1/4 tick mark, it creeps in traffic until the fan kicks on (I installed an e36ti e-fan in lieu of the clutch and aux fans), then promptly drops back down to the the 1/4 mark. Seems low to me as the previous m42 I owned was right below the 1/2 line most of the time.

Also in regards to the overheating, it might have to to with the heater core valve near the firewall?