After flogging on his car tonight it started to get hot. Pulled over and coolant spit everywhere and was down the side of his passenger side. The car has a greddy 127kpa radiator cap, C&R aluminum radiator, 160 degree stat and the fans are definitely working. I'm hoping for an easy fix, we're gonna toss in a new stat and replace the cap. For a quick fix its likely going to be an autozone special which is 180 degree I think. I was thinking of drilling a small hole in the stat to let a little bypass and keep things a touch cooler. If this doesn't solve it I figured we'd do a compression test to see where things are at. Sound like the proper course of troubleshooting??

Also, question for burping the coolant system on a 2gnt. When I start his car cold w/o the cap on water shoot up 2 ft like a damn fountain. This is normal right? I know on other cars you can take the cap off and let the car run to get rid of air bubbles. I looked in other posts and when this was recommended the person almost always responded that they tried and shot water all over the place. Just want to make sure this is expected.

Thanks as always.

considering the obvious which you already have, which would be to make sure the thermostat is good and system is bleed.

my many years of experience will tell me that you have a bad head gasket. at this point its a small blow. compression is basically dumping into the coolant system and the cap rating is high enough to just force the coolant to dump into the overflow, until it fills up and then it overflows.

an easy way to check this is, to replace the t-stat like you want to, and then start the car up, let it run until it bleeds out. put the cap on, and then run the motor at 2-2500 rpm while you sit there and watch. at this point the cap will be on. eventually the coolant will start to bubble out and into the overflow.

if you have a radiator funnel you could put that on, and watch the coolant continuously bubble as if it were always trying to bleed.

easier way to test the therm is just pull it out, and run it without run wont hurt the car, if that helps then just replace thermo or leave it out, also take the radiator cap off and start her and see if the water if flowing the pump might not be working