sludge in coolant

Small amount of sludge in expansion tank on fill line. 90 325i stock.

Here is some pics of the sensor pulled out

typical if you use tap water to mix with the coolant.

i would recommend doing a coolant flush. cause whats one the sensor, is in the block in the radiator and anywhere else the coolant flows.

Just did timing, water pump, thermostat, an flush. Seems to over heat still. That's why I asked that thought that might be oil in the coolant so blown headgasket witch is why I over heat. Could it be a bad radiator?

Well if tou have just did all of this work. And you flushed the ENTIRE SYSTEM out thoroughly. Then (and only then) should a blown HG be suspect.

What condition is your rad in? Does it have holes, smashed in fins and such? Could be your problem.

Originally Posted by First time

Well if tou have just did all of this work. And you flushed the ENTIRE SYSTEM out thoroughly. Then (and only then) should a blown HG be suspect.

he didnt change the fan clutch, so he still has a couple options.

check the fan clutch. easy way i did it was get the engine up to op temp, shut off and try spinning the fan by hand, should have a resistance. or you can do the newspaper test. roll it up and jam it in there while the engine is running.

Oh an forgot to mention I did change the fan clutch. My radiator is prob the stock one from 89/90 and no damage to it all. Could always be clogged internally tho with junk. Could it still have air in the cooling system?

Air in the coolant would explain the car overheating but it would not explain the sludge.

If the radiator is original, i would place a bet that the sludge is in their.

Air in the coolant would explain the car overheating but it would not explain the sludge.

If the radiator is original, i would place a bet that the sludge is in there.

Sorry double post.

Yea thats what I figured. This guy I was talking to was saying radiator also. I will replace that then since that's all that's left on the list besides the head. Is there any other way to bleed the air out in the cooling system other then the screw on the thermostat housing?

nope. I believe that is correct way to bleed the system. Hopefully the new radiator will solve you problems.

Your radiator shop guy will be able to ID oil sludge / HG problem from your old radiator. Try a 1/16" hole on the flange of the 'stat and orient that at the top. It will aid bleeding a lot.