Tell me what I don't want to hear.

[Aptyp]

What it is: m50 with a 318ti radiator.
What it does: temperature creeps up until I am forced to turn the car off. Coolant level drops and top radiator hose is dry after a short drive.
what has been done: thermostat is new and works. Waterpump is new Graf. Radiator flows perfectly. No coolant leaks. No heater core, so there's not an air pocket there. Car doesn't smoke, there's no oil in coolant and no coolant in the oil.


Did I miss something, or is it that new engine time?

[mrcheezle19]

well if there's no water in your coolant that could be the issue right there. Adding water helps the coolant dissipate the heat better. I would add water to the coolant.

[ian e30 318is]

+1 for the water. Also what about a fan? Sounds like you forgot that. My temp would also creep when sitting still in traffic or at a light when I did not have a fan to force air over the radiator. Wire in a pusher or puller fan mounted to your radiator and it should solve your issue.

[K1CKBAC]

If you just replaced the radiator it was probably just in need of a top off.

[mrcheezle19]

yeah definitely check your fan as well. Make sure it is working and coming on at the proper times. IIRC it should be 2 stages. one low speed before the half way line and then high speed when you reach the halfway line or go past it.

[bimmer630]

I think he meant no water in oil and no oil in the water. I can't see a car overheating just because it has straight coolant.

Might be an air bubble.. I let them sit after a short run then recheck. Does the 318 radiator haveva bleed screw?

[ieatpeople]

i think OP was alluding that the head gasket is letting go....



do a compression test, let us know how it looks.

[Aptyp]

yeah, there's no reason for coolant/water to disappear and top rad-hose become dry.

Compression test coming up today.

[e30rapidic]

hopefully not a cracked head... check spark plugs as you pull them and see if you have a "clean" one.

[DREWHALL]

Was gonna say, look for the steam cleaned cylinder. If any of the plugs come out looking cleaner than any others or the piston tops, if you can get a look at them through spark plug holes, look particularly clean then you have coolant entering a cylinder.

[Mossman]

Coolant has to be going somewhere, if it's going into the cylinder through a head crack or a failed head gasket in any decent quantity you would know it from white exhaust smoke and a sickly sweet smelling exhaust.

[future rs]

I'm sorry to break this to you. But you're fat....

[rightcoastbias]

My m42/318is radiator required me to jack the front end up ~2' and run the engine for ~20 minutes before it would bleed properly. I have not had a single issue since.

*Note: My M52 is running an 82 deg thermostat, 16" pusher fan and the heater core is connected.

[FredK]

Check that you don't have a 1.4 bar radiator cap. It will have "140" printed in the center of cap.

You need a 2.0 bar cap. It will read "200".

Easy mistake to make, as I've done it before with an M42 radiator.

[Jluke]

Mabey head gasket leak, if i were you, look for combustion to the water side not water to the combustion side, look for bubbling coolant/smoke coming back through your reserve.

Though that's the extreme side, check the simple stuff first, fan kicking on, no lines blocked, water pump working.

Also did this happen only one time, or multiple times. Just once might be an air pocket, more than once would be bigger problems.