90 GSX coolant problem (over pressurized system???)

[slowacura]

So I've purchased my 4th dsm, a beautiful 90 gsx with ****ty paint :)

I replaced the 14b, rebuilt the head, added 3" turbo back exhaust, safc, 255, 550's, mbc, 2g mas, new clutch, etc etc etc....

My problem is, that after I drive the car for long periods of time, the coolant overflow tank bubbles, the line is releasing excess pressure into the tank. I cant for the life of me figure out what the problem is. The head and h/g are new(4 layer w/arp's and completely rebuilt head that was resurfaced) Compression is 160-162 across the board, I repaired the only two leaks I found with my sweet craftsman coolant pressure tester, but thats it! Any helpful ideas would be greatly appreciated. I am going to be changing the thermostat just to make sure a dumb 2 dollar part isnt hanging me up... Please gimme a lil help guys!

Thanks!!

John

[turbo4g63]

is it overheating at all? Sounds wierd, i've never had that happen to me so i don't know what to tell you...did you post it up on philly dsm? you would probably get a response there...or check in w/ pale dsm on here (erik from jnz)

[slowacura]

not overheating at all... temp needle may move hotter by a 1/8" for a few seconds, but drops to normal in a matter if seconds. Yeah its really got me stumped too... Been scratching my head for a week.

[SpendOne]

Did you try a new rad cap?? Cap could be shot. When you open your rad cap, do you smell exhaust fumes??

[MissDSM]

im not even going to pretend I know this is whats wrong, lol, but my gst was overheating and my coolant overflow tank would bubble and i would leak coolant when the car was off. I assumed it was the hg, but my friend thought it was the thermostat or cap so we changed the thermostat first. It doesnt overheat now, coolant tank doesnt bubble, and it leaks a tiny bit of coolant when the cars off. Ill still replace the hg, but the thermostat fixed the majority of the problem. My friend who has a 95 gst is on his 3rd thermostat and 2nd radiator cap.

[slowacura]

Did you try a new rad cap?? Cap could be shot. When you open your rad cap, do you smell exhaust fumes??

Unfortunately I did, it was one of the first things I attempted.


And MissDSM, The headgasket is a new(well, 6,000 miles old now) mitsu 4 layer, and there are ARP's on a fresh head, so I can't imagine that is the issue, lol, esp running that awesome 12psi I had it set to for break in(bumping to 16 tomorrow, limited by the damn stock intercooler... If anyone in NJ wants to help me out, I'll gladly pay cash, beer, or smokes... Its a problem that really, just flat out pisses in my cheerios every day

[Nors]

LOL @ cigerettes. Try flushing the system then adding new coolant + Bleed the system.

[slowacura]

yeah, I was gonna do that also today when I replace the thermostat

[Hans_GZP]

Sounds like you have a bad thermostat and air pockets in the cooling system. Definitely bleed it out and make sure the fans kick in.

[MissDSM]

Unfortunately I did, it was one of the first things I attempted.


And MissDSM, The headgasket is a new(well, 6,000 miles old now) mitsu 4 layer, and there are ARP's on a fresh head, so I can't imagine that is the issue, lol, esp running that awesome 12psi I had it set to for break in(bumping to 16 tomorrow, limited by the damn stock intercooler... If anyone in NJ wants to help me out, I'll gladly pay cash, beer, or smokes... Its a problem that really, just flat out pisses in my cheerios every day

no i wasnt saying it was the hg, i was saying the thermostat since I had a similar problem, and the thermostat fixed my coolant tank bubbling.

[slowacura]

the fans are def kicking in..

And sorry if I came off confusing MissDsm, I was just explaining for anyone who reads that its def not the h/g... I certainly appriciate all the insight everyone has offered, I will let you know how I make out after I'm done tomorrow.

-John

[enigma]

When you bleed out the system, put a funnel in the rad cap spot, fill it halfway with antifreeze, and rev the engine. Make sure the funnel is nice and tight in there, and you should see plenty of air coming out.
It took about a week of driving for all the air to come out of my car, i think most of it was trapped in the throttle body, then redistributed itself throughout my engine.

[turbo4g63]

my car was actually acting up a few weeks ago. the gauge was moving up an 1/8 of an inch then it would go back down. it would especially do that when it was hot outside like 90*+. then i bled my system and it seems to have solved my problem. i saw a bunch of air come out. it hasn't acted up since then.

[slowacura]

Well, I burped the whole system well, and for good measure changed the thermostat, and water lines to the turbo. Thanks for all the insight guys...

now onto my next problem, I failed emissions terribly :)

[SpendOne]

emissions...whats that??

[slow4cyl]

I failed emissions terribly :)


You didnt give the guy inspecting your car a big enough tip. :wink:

[slowacura]

You didnt give the guy inspecting your car a big enough tip. :wink:

Yeah if only they'd take the damn money in NJ... bastards! The state has a tight grip on all their balls