A BHG (assuming it is causing overheating) could take any amount of time depending on how quickly air is escaping and causing the airlock (or how much coolant is escaping/how long to deplete system enough to overheat whats left).
Do you actually have any other symptoms of BHG? If it's a BHG causing the overheating you have to be losing coolant at the very least, either blowing out of the overflow tank or burning it. To be honest it could just be something simple if the head was torqued & everything prepped properly. How long is it actually taking to overheat (is it actually overheating, what is the engine temp measured independently of the gauge?).
__________________
'89 MA70 Supra GT aero 3.0turbo JDM, Rebuilt motor, K&N intake, 3" stainless turbo-back. New turbo and braided line kit...
'89 Honda NC27 400, NC23 cams, open pipe, PC36a shock & possibly Showa USD forks...
'83 Yamaha 29R XJ750E-II, number 69 off the line, only runner in the country? Original except Koni shocks
'95 Honda PC26 CB500R, Winter hack, hateful, trying to sell it
I'm not paranoid, they really ARE after me!!! 
|