HI. i just had my radiator out the other day,to make a repair on the piece where the overflow tube hooks up. it was loose. so i had that fixed and put the rad back in. then i noticed something in my overflow tank,,it looks like a film of either oil(hopefully not) or tranny fluid possibly. its light brownish in color. I cant tell if its one or the other. is there any way i can tell? i never noticed it before the swap,,,but it may have been there. last week my car was running hot,,and i could not pull over for about 5 mins...so i was babying till i could. so im thinking head gasket blown possibly. im just not sure how to diagnose this film in my overflow. small periodic bubbles can be seen in the overflow tank while running the engine at idle. is it possible the tranny lines to the rad need re attached maybe..or is it the head gasket? ...thanks

 

I have a problem like this last year but my radiator failed internally. The transmission lines inside the radiator busted and then one day while taking mine out for drive, the transmission didnt have any power. Checked the radiator and all of my transmission fluid was in my cooling system. If this is the case, just make sure you run some cooling system flush through the cooling system before adding more antifreeze.

 

Did it actually overheat? Through my own idiocy I let mine overheat pretty badly several months ago, coolant had been nice and green for years. Coolant went brown, and I got a nice layer of that brown stuff deposited in my nearly-new and prisitine white overflow bottle.

After basic health checks - compression test etc, found no sign of anything untoward with the motor. I don't have my radiator tranny cooler hooked up - figured I just boiled off a bunch of scale/dissolved rusticles out of the head/block coolant passages.

Drain coolant, flushed heaps etc, new coolant, but could not get the discolouration out of the overflow bottle - still annoyed about that. Motor runs fine.