strokerblackhawk

iTrader: (4)

this may have nothing to do with your problem but my car was doing the same ****, i even replaced the overflow bottle new hoses and every time i would nail it or drive for an extended period of time i would notice coolant all over the passenger side of the engine bay, could figure out for the life of me where or why it was leaking. This was after i got my car back from the shop doing major motor work on it, well one day i was under the hood trying to find where it was coming from cause for the longest i thought the bottle was leaking or something, so i started slowly increasing revs in my drive way looking for water to come out of the overflow, and ill be damned if after 4k rpm my radiator had a leak that looks similar to a squirt gun where the plastic sides where crimped to the aluminum finned part of the radiator and then it hit me if someone layed across the aluminum part of the radiator while doing the heads it could cause it to leak cause the plastic part is what holds it in place, so my guess is the guy maybe put to much weight on it but, at idle until 4k rpm's it wouldnt leak at all over 4k a couple of times and there was coolant all over the place an i couold have sworn for months it was the overflow. hope this helps!!!

jetaws6

iTrader: (3)

Thanks for the input but you can clearly see that it is out of the overflow I will check my rad though just to make sure.

LS6427

iTrader: (2)

A blown head gasket leak can hide from a coolant system pressure test, if its a tiny little leak and depending on where exactly it is. The upstroke of a piston on the compression stroke is thousands of times more psi then a 18-20 psi coolant system pressure check. Then think of the psi on the power stroke when the fuel air ignites.

You might be getting the leak from a cylinder (blown head gasket) only at high rpms because the leak is so small and it takes that big power stroke at high rpms to overcome it.
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But do that test first....its free and easier. If that shows no drop in pressure over a given time period.......then I would do the leakdown check. And only let someone do the leakdown check who has done them before.

Or, get the car up on front end ramps AFTER the engine is at operating temp......then turn it off and wait 20 minutes. Come back and with a flashlight, look for tiny pinhole leaks. The pressure and temp rise for about 20-40 minutes.....this is when a tiny leak will show itself. This is essentially a coolant system pressure test.

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LS6427

iTrader: (2)

You are getting air in your system....thats a fact. But from where. It could be a tiny little leak somewhere, and when the engine is turned off it will **** coolant out....then over time you have an air pocket. That causes temps to rise, which causes pressure to rise. Then you will get it blowing out the overflow.

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wssix99

iTrader: (5)

The pressure tester fits where the radiator cap goes and you pressurize the system with air. If the air pressure falls, its an indication of coolant escaping from somewhere. If you get a leak, you'll see it. If you don't get a leak, then the fluid is moving in to oil passages or the cylinders.

As LS6427 points out, the pressure test isn't fool proof, but if its an exhaust leak that's bad to the point where coolant is shooting out of your bottle, then I'd expect a pressure test to expose that.

Lots of other probable causes too, but the pressure test is the first place to go and eliminate causes.