View Full Version : please help!! overpressurized radiator

05-03-2009, 10:09 PM
hi i have 2 90 SC's i just replaced head gaskets on, both deck and heads were not warped, they were within spec when checked with a straight edge, but for some reason they both have pressure in the cooling system right after you start it, one kept pressure for a few days after it not running, i used felpro head gasket set with new head bolts and torqued properly, i cannot figure it out, and am going to lose my mind if anyone else has this problem or has seen this problem please let me know, again i am going crazy haha, thank you all for your help.

Kevin Leitem
05-03-2009, 10:22 PM
did you have the heads pressure checked? could be a cracked head

05-03-2009, 10:35 PM
>i used felpro head gasket set with new head bolts and torqued properly

Just curious which way the hgs were installed in respect to fore/aft & coolant passages...

05-03-2009, 10:46 PM
that's exactly why i'm taking my heads to a professional engine bld./machine shop. for the amount of pressure ,and two the different matng surfaces, these engines have, there's just far too many intricate and fine things to rework and consider. with all that time and work i don't want to have do it again anytime soon.:eek: .......and plus the fact i know i don't know enough of what to look for. let me know what you find. hope i don't have to go through the same thing.:(

05-03-2009, 11:43 PM
i did not have the heads pressure checked

i don't honestly remember which way they went on, but i am pretty sure i did what seemed most logical, considering they said front on them, but even if i did put them on wrong how would that cause this problem/?? just wondering?

yeah if i pull my black bird back apart i will have a machine shop check them out, this just sucks cause after 2 years i finally got her back together, FMIC, 46 lb injectors, 3" CAI, ported manifolds, 76mm maf, 5% pulley, underdrive pulleys, short throw shifter, stage II clutch, 92 fuel tank, 255 fuel pump, and now i might have to tear her all back apart, like i said i am going to lose it lol :(

05-04-2009, 12:46 AM
dam nova im sry to hear about your problems, unfortunately thats what happens with us die hard sc enthusiast. I own 4 and of those 4 only one runs which just so happens to be the one that I did a 351w swap on (go figure) anyway, I'd recommend that you do a pressure check before doing anything or cracking into the engine again. I think you can rent the radiator pressure test kits from autozone for a few bucks. Just pump it up and let it sit for a few minutes, if you loose pressure then you have a problem.

Also, I've seen some people install the thermostat backwards, the spring is suppose to sit inside the intake, if you install it backwards you could get similar problems to which you were describing.

05-04-2009, 10:06 AM
yeah i have a pressure tester i will do that and check the thermorstat and might just pull it out and see what happens i am so bumed

05-07-2009, 02:50 PM
havent got around to pressure testing it yet, but i was wondering, are these common for having ed heads???? i have been sick so thats why i have messed with it yet, i am sure it is probably the worst so i get to dump more money into my bird :( thanks for the input guys!