h-o-n-d-a

My gsr motor overheats when i go out and drive it. but ive let it sit and idle for a half hour and it stays right half way like it normally should and doesnt overheat. both coolant hoses get hot and the fan goes on and off like normal. The motor was rebuilt and headgasket changed along with the rebuild. I want to try and rule out headgasket as a possibility should i remove the thermostat and run it open ? its a half size aluminum radiator and slim fan with a moroso coolant catch tank. . i also find the tank to fill up after a little bit of driving. any suggestions to rule certain things out

tw1tch

I would make sure the head gasket was replaced correctly. If the head was warped at all and it was not addressed, then you could change it 100x and still overheat. What kind of driving makes it overheat? Usually the cool air on the radiator can keep the temps down. I think you're looking at needing to get the head checked and a new head gasket, but hard to tell from these limited details.

h-o-n-d-a

well the head was machined and checked throughly. the block was checked with a straightedge. i just dont get it. usually if it wants to overheat you would think itd do it at idle too. it can sit for an hour and not overheat. but if i take it out on the road it goes up and goes down. but more or less stays above half way. anything else to check?

h-o-n-d-a

yesterday i topped off the coolant because i think it was a lil low. so i started it up kept it at 2grand and nuthing. it sits right below the halfway mark. but i didnt get a chance to take it out on the road to see if it does it again but im willing to be it probably will go above halfway

Former User

Is this saying that you are losing/leaking coolant somewhere?

h-o-n-d-a

no leak but i find that the overflow tank fills up and steams off outta the pin hole on the top of it. but it doesnt overheat while its sitting. it sits perfect on the gauge.you'd think if it was gonna overheat itd do it there if it was somthing serious. does the overflow tank have to be in the same height as the top of the radiator? mine is a lil lower tucked underneath off to the side.

Former User

I would have to agree with tw1tch. It sounds like a blown head gasket that is allowing exhaust gas to be forced into the cooling system. You may be able to purchase an analyzer kit that tests for exhaust gas in the cooling system.

Jas9848

iTrader: (2)

head gasket. take the radiator cap off and start it up and if coolant shoots out or bubbles up, then it's definantly the head gasket, but it probably is anyways, especially if the overflow is filling up and bubbling over compression is leaking into the coolant system through the blown head gasket.

h-o-n-d-a

ughhhh. such a pain again. this is the second headgasket ive had done on it. The first got pinched by and wasnt aligned correctly and the guy didnt torque it to spec and it leaked oil lol everywhere. now i replaced this one with a oem honda gasket and got everything straight started up fine and never overheated till i was ready to take it out on hte road. then it started rising up. im ready to just get a new motor and part this one out. learned my lesson.

waaBAAH

keep driving it around... work those air bubbles out. give it some time before you do a head gasket.

temp going up and down is more of a sign that there is air in the system or sticking thermostat.

start with easy first..these hondas are so difficult to get air out of the system compared to other cars.

h-o-n-d-a

well its just weird. ud think that itd overheat sitting still if air is getting in the system. but it doesnt overheat when i just let it sit. it goes up when i drive. this sux. does anyone know if the coolant overflow has to be level with the radiator? i thought that may need to be fixed too

Former User

You offer a lot of good advice on the forum but, in my opinion, the OP should disregard this suggestion. Continued driving with an engine that overheats risks destroying it. OP -- If you think the problem is caused by air trapped in the cooling system, then it would be safer to perform a thorough bleed.

Former User

If some of us are correct that the head gasket is blown, then one possible explanation is that higher cylinder pressures produced while driving versus idling allow exhaust gas to breach the bad head gasket, enter the cooling system, and cause overheating.

I don't think the relative height of the reservoir to the radiator matters.

waaBAAH

i take for granted that not alot of people know to shut down the vehicle while overheating.......what i meant is drive it still...if it starts to go above 220 or whatever your gauge says "nomral".. then shut the vehilce down...wait a couple of minutes then continue on. some hondas dont have a bleed valve..some do.

if you suspect air bubbles..jack up front end as high as possible and have the cap off and let idle for awhile....the air bubbles should work themselves out.

sorry if this is kind of backyard mechanics but i could say.. pressure test this..pressure test that.. take a temp reading...probe the radiator for exhaust gases. instead i am offering easy DIY for cooling systems and such for others.

not harm taken ron...

hdzhonda96

my temp gauge says it overheating but does not show any signs of it. it shows its overheating when it idles but when i get going the temp goes down. on the freeway it shows that it wants to go up but does not when i come to a stop it does the same thing again...what could be the problem?

Former User

Does the radiator fan run when the engine is hot and idling?

hdzhonda96

the fan comes on when the temp, rises past the halfway mark. but if the temp coolant sensor is bad would that give me false readings

Former User

Your fan switch and coolant temp sensor are fine. The latter measures but does not control coolant temperature.

Try replacing the thermostat and bleeding the cooling system.

hdzhonda96

i changed the thermostat and bled the system but the temperature still rises like it has been doing. the fan doesnt turn on when its sitting and at an idle..what would make the car heat up so fast... one minute we take the radiator cap off fill it with water and coolant put it back on turn the car on. we try to take the cap off after a minute...the car was so hot that the cap blew off... what could it be

92civlude

Does it overheat with the fan switch jumped? Are the fans turning the correct direction? Did you replace the thermostat with a cheap aftermarket chinese knock-off?

robfrmny21

seen this issue be4 with defective water pumps. pump spins normal at idle but slips at higher rpms cuz it broke off the shaft that spins it.

slow96lude

i had this problem with my full build gsr and i thought it was the tune running to lean and it ended up being the oil pump starting to go out. another way to check the head gasket is to get some carb cleaner and spray aroung the head gasket while running and if idle spikes you have found your problem

civicCX92

Try getting a new water pump. Its possible that its slipping like robfrmny21 said