SolidSpruce

guys i need help, my car overheats when i drive it hard. At first i thought it was because the coolant system couldnt keep up. I have a b16 w/ a fluidyne radiator w/ a fan running full time.
what happens is after driving it hard and coasting or coming to a stop, the temp will start to creep up, as soon as i start driving temp settles back to normal.

i started to monitor what was actually happening with my coolant, and came to realize, that my resivoir was overflooding....i grabbed my radiator and it was cool to the touch, yet me car was overheating! i grabbed a fat towl, put it over the cap, and opened it, to my surprise no coolant came out, just air pressure release, and i looked into the radiator, and realized that the coolant level had dropped below the upper hose line that feeds the engine.....which explain why it starts to over heat at an idle after a hard drive....there is no fresh water being put in....and when i accelerate, coolant pressure rises enough to start pushing water back into the motor...

ive purged, bled, everything to get the air out of the system; ive changed radiator hoses, ive changed radiator caps (special order $19 from fluidyne), ive changed thermostats (tried a 190 and a 170). ive done a coolant pressure test, and it held 30psi for over 15 minutes.

last night when i ran it at the track, i had to top off the radiator between runs....it sucked bad, because there is a problem and it needs to be addressed and ive run out of ideas.

one guy suggested the idea of a leaking headgasket - not necessarily 'blown', but leaks just enough that under boost pressurized air gets into the coolant system...
i can see how that may be a possibility, but how does one check for that? i really hope the only way to check isnt taking the head off and do a visual inspection of the gasket....

ideas and comments welcome, thanks!

DaveF

i used to have a major problem blowing headgaskets.

the olny time it would push the coolant out of the rad and into the resivoir was when it was boosted on. than there wouldnt be enough coolant in the engine so the guage would rise very quickly. .....i am almost sure that you have a blown head gasket.......

but than again its possible that you have huge air bubles in your system.


edit...what kind of block and headgaskt are you running? and is it o ringed?

SolidSpruce

how would i check for a blown headgasket? i dont blow white smoke, i dont smell the pancakes, i pulled the plugs and they are all dry, i did a compression test on the cylinders and it was 150, 151, 148, 150.

if my headgasket is blown: what should i replace it with? the one i used when we built the motor was just an OEM headgasket....
should i get somethink like a hardcore copper one? or a particular brand?

DaveF

you would have to do a leakdown test. i dont think a compresion test would necessaraly do the trick.

my car never blew white smoke either...because the "boost" would push into the coolant chamber..not the coolant into the combustion chamber. maybe it would smoke at idle but not when boosted on.

SolidSpruce

im not familiar with how to do a leakdown test.....is that something i should ask the dealership to do? i dont want to take my car to joe' blow's mecahinc garage...

DaveF

you should be able to get a leakdown tester from snap-on for cheap. its not hard to do.

SolidSpruce

yeah, im up for trying that! could u give me a brief description of whats involved in performing a leakdown test?

CivicSoul

I just fried my headgasket last night! My problem was that I reused my head bolts! A big NO NO! I am getting arp head bolts right NOW! If you plan on buliding a serious boost monster, look into the the greddy head gasket as well.

T4eg

i would do a leakdown test. They are very easy to do. That will show your your problem