rockit

iTrader: (3)

hey i've been driving my 87 l98 gta a lot lately. took it on a trip to indiana, went 500 miles and got about 20 mpg, not too bad, right? on the way back the car was overheating very slowly, if i went over 70 mph for too long it would climb up to 260*, it does this consistantly now everytime im on the highway. in city stop and go its cool as a cucumber but at cruise it starts to climb in temp slowly. Also to go along with this my gas tank gurgles briefly, maybe for 30 seconds after i shut the car off. i'm not sure whats causing either problem or if they are related and any insight is appreciated.

some info about the car:

the cam is an unknown, the motor is a new jasper piece, i have correct heads but i don't know about the cam, i'm running a 15.1 at 91 with a 2.1 60 ft so it's probbly not far from what its supposed to or else it's close enough for the maf system to compensate.

the car has a hacked together exhaust that has the orginal y pipe with a 3 inch section replacing the original 2.5 inch collector, and it's 3 inch from there back.

my mods so far include a 160* t stat and a tb coolant bypass

3.8TransAM

Run a 180 not a 160 stat.

It always staying open can contribute to overheating in higher temps, it needs time to be in the radiator to cool before going back into the engine.

Several prom parameters will also not be met on a regular basis at 160.

Plugged radiator, sticking t-stat, weak water pump, collpased hose can also contribute as well. Are your fans working?

# 1 issue with overheating is the missing lower valance/air dam across the front, our cars are bottom breathers.

Fuel tank gurgling is usually caused by inop purge system(not releasing pressure vapors) or fuel tank vent valve not allowing fresh air into the tank.

Start there and let us know what u find.

later
Jeremy

rockit

iTrader: (3)

i wondered about that valence, mine is removed as it was hanging off when i got the car, i still have the larger plastic peice that swoops up into the engine bay but not the inch and a half tall one that goes all the way across the car underneath. is there a way to improve flow, will removing that rubber at the back of the hood help?
the thermo stat is brand new i just put it in to combat this problem and it didnt help at all. as far as a 180, the tech article says closed loop is achieved at just over 100 degrees, in addition as i said it made no difference im still running at the same temps as i was so either or im in the same boat.

i need help with the tank venting part of things as i had the same idea, yesterday i replaced about eight feet of crumbling vacuum hose in the pcv and charcoal canister systems, no difference tank still gurgles. i need a check procedure for this system as well as locations for the vent you peak of and how to inspect the charcoal can system.

the rad is from my camaro, also a v8 but a 305, is there a difference in the thickness of the rads? i know its fine my camaro never went over 180 degrees even while racing the 1/4. the hoses have 5000 mi. on them but the water pump is an unknown, probably the original peice.

i appreciate the help, if it seems at all as if im being rude in my replies its because i distracted thinking about the problem as i type i really do want the help.

joejoe

iTrader: (1)

It will only get hot on the freeway, and cools when leave freeway? If so check your timeing, a little to advanced will cause it to do that, if dis. was loose it could have turned a little on your trip.

rockit

iTrader: (3)

its at roughly 7 degrees. how much timing is required to make that happen?

i never would think of timing, whats crappy is theres a hour long trip down the highway to get to my timing light

im getting a new charcoal filter and i'm going to inspect all the lines from the fuel tank for kinks etc. because in certain cases the pump is cavitatiing and sometime vapor locking highway or city and im sure it isn't helping the cooling situation to have a lean mix goin on.