iv been battling a coolent issue for 2 months now can not figure it out.
so i fill it up will one of those funneles that lock on the top of the rad so you can over fill the funnel to blead all the air out .and i run the car for 45min and no problems. stays cool. then i rev the motor to 3,000 rpm and the funnle fills up with coolent like it is being filled up with a garden hose, seem odd but then it go's back down after you let off the gas. then i go for a drive boosting it hard for a few pulls like 5 then it starts over heating,stop let it cool. drive home normal and it fine for a little while then it starts over heating again. it spews coolent all over the engine out the over flow. i raised the radiator put a new thermastat in and tryed bleedin it a million times. the last time i noticed i had a ton a pressure on the radaitor hose and i opened the bleeder at the head and it pissed air out for like a minite and a half. whats wrong. it is a new built motor 500 miles on it . works great other wise

 

try block testing it, if coolant is gushing out of the rad. fill, with air bubbles=head gasket

 

I'm having the same problem. Mines a stock boosted LS on 7lbs. When i hit boost the coolant would spray out the overflow tank. So far I've popped both heater hose and the lower radiator hose. Its an Aluminum radiator if that matters.

Wish i could help but I'm in the same situation as you. So far all I'm reading is that its the HEAD GASKET. My leak down/compression test are good so I'm stumped. I'm going to take the slow road and start from simple to complicated. New radiator cap & new thermostat. about $25 and 10mins of work. Then bleed the coolant system again. See if that helps any.

-Has anyone came across this and found a solution?

 

head lifting , possibly from detonation but your getting cylinder pressure in your cooling passages changes the headgasket and studs make sure everythings flat while your at it

 

Once there is enough pressure in the cylinders, its lifts slightly and since the cylinder pressure is so high, it goes into your coolant and the high pressure prevents oil from getting into your coolant.

You can have a test done at a shop, they test your coolant for hydrocarbons, and that will tell you for sure that if that is the situation.

Sometimes you can also see bubbles in your coolant with the rad cap off, that will also tell you there is something wrong with your headgasket.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by D@nnY &raquo;</TD></TR><TR><TD CLASS="quote">head lifting , possibly from detonation but your getting cylinder pressure in your cooling passages changes the headgasket and studs make sure everythings flat while your at it</TD></TR></TABLE>

 

seams weird though because the coolent over flows even when im out of boost a 3,000 mine boosts a 5,500. it should have that much pressure at that point. when i cheak the block for leaks it it not going to show a leak unless it is boost then,when the head starts lifting? im going to cheak my arp head studs for tightness dose any body know torq. they should be at for a gsr motor?

 

not to jack the post but, i have some small bubbles in my radiator, is that normal?