nonvtec92

Hey everyone.

My car is trying to overheat... sometimes.
I can't really pinpoint what exactly is triggering it. It almost seems to be doing it after a certain amount of time and then if I downshift and drive it harder, it settles down. If I cruise along at 55mph in 5th gear, i'm fine. If it sits at idle it SLOWLY rises. I mean, after 5 minutes it'll be somewhere between half way and 3/4.

I just replaced the water pump and thermostat(which was checked in boiling water) 2 days ago.

Radiator is just a few months old.

The fan is kicking on.

What else could be causing the car to WANT to run hot?

Blown headgasket? There's no serious amount of smoke to be seen... No boiling coolant. No coolant overflowing into the overflow can. Nothing.

Any ideas?

Paul-R

i have no clue with out seeing it for myself but feel the hoses to see if there really really hot to see if your new thermostat is working right .

nonvtec92

Both hoses are hot.
I checked the thermostat in boiling water before I put it in.

mikehawk

air in the lines? you may need to bleed the system

JDMh22eg9

thats what i was thinking air in the lines would do it. try bleeding it out

95jeremie

X3 for air in the system

nonvtec92

I've let the car run and run with the radiator cap off... probably 45 minutes. Fan would NEVER come on. I stood there FOREVER!? Fan wouldn't come on.

So, I put the cap on... drove down the road. Fan came on. Took the cap off... topped it off, let it run for like 20 minutes still wouldn't come on.

Figured it was good enough?

How should I bleed the air out? I don't have an air release valve or anything. It's a d16z6

batallic

bleed the system and get back to us

honda.lioness

It is usual for it to take 35 minutes to an hour for the fan to come on during the bleed process.

Is your thermostat OEM?

The procedure for bleeding air from a 92-95 Civic is here: http://media.honda.co.uk/car/owner/m...l/pdf/10-4.pdf

nonvtec92

Thermostat is a Stant.
I guess i'll try and bleed the air out again.

Any other ideas? Is that all it could be? Other then a blown headgasket?

nonvtec92

Also... I glanced at that pdf link. My car doesn't seem to have a bleeder bolt. My old d15 did... my d16z6 doesn't have one.

How is the process different if I dont' have one?

Just leave the cap off and run the car until the fan turns on? OR should I put the cap on half way like that pdf says?

honda.lioness

Hmm, parts sites show your d16z6 having a bleeder valve. If it truly does not, try the procedure given at https://honda-tech.com/forums/honda-civic-del-sol-1992-2000-1/how-do-you-bleed-coolant-1594998/ . Note the chatter in the aforementioned thread about not having a bleeder valve and how by design air in these engines is supposed to go to the rad cap.

But all bets are off AFAIC without an OEM thermostat.

Are you losing coolant and so adding it regularly?

Did you have this problem prior to replacing the thermostat and water pump?

nonvtec92

I had the same problem I have right now.

It would overheat at idle. If I reved it way up and kept it there; the temp would go back to normal. Back to idle, or low rpm cruising it would steadily climb.

So; I replaced the thermostat and water pump.
Still doing the same thing!

honda.lioness

I trust you know that these engines are so small that traveling at high speeds is by itself enough to keep them cool. If the cooling system is malfunctioning, then siitting there idling will not remove enough heat. Cars overheat at idle, not when moving at highway speeds, generally speaking.

Thermostat or head gasket or, with luck, too much air in the system. I lean towards head gasket right now. Sorry.

nonvtec92

I've been worried that's what it is.
Hate hate replacing headgaskets. Especially in the winter with no garage.

I figured wind speed would cool the engine temp a bit.
When I say downshifting and increasing rpms would lower the temp gauge; even if I stayed at the same speed, and JUST downshifted... only change being rpms, the gauge would go down.

Don't know... i'll try bleeding it again before I change the HG