I have a 97 del sol vtec ive been working on, but im having an issue. ill turn the car on (first time the engine has had coolant and probably a month). and it has a small idle surge, every 2-3 seconds it surges slightly then comes back down. sometimes it will go away , then sometimes it comes back after it goes away. when the car gets to operating temp (fan kicks on) the upper radiator hose gets really hot, and the lower just stays cold, the upper feels like it has pressure in it, but i can squeeze it and hear a squishy noise (its hot so i dont squish for very long). I pulled the thermostat a while ago and brought it home with me, boiled it in hot water, and it opens like it should. so i dont think its that, the motor has a brand new cometic head gasket, and arp head studs, and is not leaking. no oil/coolant mix anywhere. im lost... the only thing i can think of is that theres air in the system still? when i filled it, i didnt put the heater on full blast in the car, so maybe that could be it? any recomendations? theres no bleeder nipple on my thermo housing or anywhere that i can see. radiator is a brand new aluminum performance radiator. any help is appreciated. need help soon. wanna get this beast on the road.

 

anyone? i need this fixed asap. searched a bunch, cant seem to locate the problem. i dont have a bleeder nipple on my thermostat housing (obd0 block) so should i just drain some of the coolant from the radiator and turn the car on with heat on full blast and the rad cap off to get rid of air? im stumped.. need help soon guys, thanks.

 

yes run it with the radiator cap off, no need to drain any coolant, once the thermostat opens it should start sucking it down and you will need to add some more.

If the air pockets are being stubborn rev it about to about 4000rpm and hold it for a few seconds, seems to do the trick every time.

And is your thermostat new? the symptoms you are describing sounds like a bad thermostat, even though you tested it. I would just replace it anyway, seeing as to it's only about $13 and you can rule it out.

 

ok thanks man. ill try that. reason i said to drain some coolant out, because its at the top of the radiator cap, and when i let it run with the cap off, the coolant level rises slowly until it keeps overflowing.

 

ok. so i changed out the thermostat just for precautionary measures. checked thermostat opening and water neck (no blockage). burped the coolant system after re-assembly with heat on full blast in the car. now with heat on full blast, and car idling. fan comes on and the car doesnt over heat at all, normal operating temp.. every hose gets hot. upper hose, heater core hoses all other coolant hoses, except the lower radiator hose.. its still staying room temp... im not sure if its because i need to drive the car or what, but ill find out tomorrow.. any suggestions on that? thermostat seems like its opening. i dont know tho.

 

Test drive the car around your neighborhood while carefully watching the temp gauge. Get home immediately and turn it off if the temp begins to rise above normal.

 

took it for a spin. everythings fine, lower hose just takes forever to get hot.. thanks for all the help guys