New head gasket, still running warm

[Fomocogogo]

First off the car is a 1987 325E. So since i have had this car i have been pouring massive amounts of money into it for general maint, etc. Just last week it blew a head gasket/cracked head. So i spend a couple days, tore it down, put on a 85 SETA head off my friends running car. Which i believe is a "I" head but with only 4 barrings and a E Cam. I also upgraded the fan clutch to the "I" style, new water pump, timing belt, thermostat. I also ditched my old leaky radiator for another that had been on my friends car for a few months, never ran hot with it. For the first couple days after the head swap, it ran fine, only hitting the half way mark, no more when running. Now its beginning to hit the third notch. It never goes over. Im out of ideas, only thing i can think of is one of the sensors on the thermo housing is loose/cracked. A friend wants to drill a couple holes in the thermostat to see if it helps.

Any ideas, advice, trouble shooting would help me a ton. I plan on driving this car 1,500 miles in december and would like to work out the bugs soon.

[jlevie]

First make sure the cooling system is fully free of air. The best way to do that is to use a vacuum bleeder system, but similar results can be had by the procedure below. If you see the temperature rising later and a re-bleed results in a significant release of air, you have a head gasket leak.

It is also possible that your new thermostat is bad, that the temperature gage/sensor is bad, or the SI board is failing. An independent check of cooling system temperature will quickly tell if the gage is at fault.

1) Using ramps or a jack get the front of the car 1' or more higher than
the rear. That will make the radiator and bleed screw the highest point
on the engine and facilitate removal of air.

2) With the bleed screw open, add coolant until no more air comes out of
the bleed.

3) Leave the filler cap off, or at least loose, and set the heat for max
temp and fan speed. Leaving the cap loose will prevent air that's still
in the system from causing a "coolant fountain" once the engine heats
up. Start the engine and allow it to warm up to operating temp. As it
warms up occasionally crack the bleed screw to release any air and top
up the coolant as necessary.

4) Once the engine is at temp bring it up to 2000-2500 for a few seconds
several times. Then crack the bleed until no more air is released. At
this point the heater should be throwing lots of hot air, which
indicates that the heater core is filled with coolant. You may have to
repeat this a few times to get all the air out.

5) Drive the car a bit, allow it to cool back down, and recheck the
bleed for air. Over the next few days you may get very small amounts (a
few bubbles) of air out of the bleed screw.