Hi I'm new to the forum- my civic 01 keeps overheating- I'm not sure if it's actually overheating but the dial is very spiratic and goes about hot... this happens when I use the heater or go over 60pmh. I already put in a new radiator, a new temp sensor, and a new thermostat was also put in less than a year ago. Any suggestions?

 

Does the radiator fan come on?

If not, have you checked any of the fuses or relays? (number 9 and number 10 fuses in the under-dash fuse box)

Are you losing any coolant?


Sometimes the temp. gauge goes nuts and the gauge assembly needs to be replaced. Other times it's a problem with the ECU, or the Multiplex Control Unit. We'll worry about that later. Do the easy stuff, first.

 

also check ur radiator cap i had to replace mine due to overheat and spitting all coolant out also make sure its a 1.1

 

mine is doing that also. and i just replaced the thermostat and radiator cap and it will still drain the antifreeze out of the radiator and my resevior will always stay full. also did a pressure check on the system and was no leaks

 

Doesn't make sense. If there are no leaks, where is the coolant going?

If you can't see a leak, and there are no signs of a leak (coolant on the ground under the car) then it can really only be going one place... into the engine.

 

Could be a warped head/bad head gasket. The coolant wides high in the resevoir and begins to overflow the resevoir. thats where your coolant might be going. if your thermostat is fine, and every thing else is fine (fuses, fan switch, thermostat, radiator, water pump) then its most likely a the warped head/bad head gasket.

 

Ok so no leaks and i put a new radiator cap on a few weeks ago and the fan works fine. I just put in a new thermostat (even though the one i had was 6 months old) it seems to be fine now but we'll see i'm gunna take it up a few hills today

Thanks for all the advice i'm hoping it doesn't have anything to do with the headgasket

 

Let us know what the outcome is.

 

After you replaced the thermostat, did you burp the cooling system after refilling it?

 

yea i did burp it. so the issue still remains... it's usually fine except for when i put the heater on so i can't use the heater... that and if it's really cold outside. ironic. i'm guessing it's one of the bigger problems maybe the headgasket or waterpump...is there a way to find out which one?

 

Yes. If you see leakage around the waterpump, then it's a waterpump leak. To check for a bad head/head gasket, you can take it to someone who can perform a test on it. The head gaskets rarely go bad anymore. Normally its just a warped head that needs to be resurfaced. If that is the case, you will need all new gaskets and a bunch of other parts.

 

False. This has been a major problem for our engines. It's been such a bad problem there's a TSB. Just because you can't see any change in the coolant doesn't mean your headgasket is good. Have them run a test for exhaust contaminates in the coolant.

 

Headgaskets rarely go bad.... It's more that the head, itself, is the culprit. Not necessarily the headgasket. If and when you do have a bad head, the problem is that the head ends up getting warped. this can cause water leakage or exhaust fumes leaking into the coolant, adding air into the cooling system and pressuring the coolant into the resevoir. This is why a lot of times the coolant rides high in the resevoir. It's not a cracked/bad head gasket. It's a warped head.

 

I'm not saying the head couldn't be bad. You should always check the head when the gasket goes bad. What I'm saying is the D17 engine is known for this and USUALLY it's just a gasket replacement. TSB's are there for a reason.

 

Hi. Be sure about the head gasket, even when its a common problem.

If your car works fine without the heater, could be the heater system. Do you see water inside the car?, specially in the passenger side? Do you make the leak test with the heater turn ON. If your car is low on coolant or an air bubble in the system and you turn on the heater, it helps lower the temperture not the way around. Not using the heater does not help if you have a problem with the head gasket or the head. CHECK the HEATER SYSTEM FIRST before any mayor repair like the head gasket. When you gauges are eratic is a common symptom when the coolant is low and it moves up and down when you turn right or left.

To check the water pump is easy. With the engine cold and running check the pump, you should see water drops coming to the floor and with the engine hot the leak stops ( most of the time ).

With the head or head gasket is not that easy; could be tricky, but check for water in the oil and check bubbles coming from the radiator ( radiator without the cap ) with the engine running and HOT!. If a leak test turn OK ( your head is OK ) but you still may have a problem with the head gasket because the leak test is done when the engine is cold, this is common with small leaks and the leak occur only with the engine running hot ( problem with the head gasket).

 

Ok, so no leak and put a new radiator cap a few weeks ago and the fan works well. I just got a new thermostat (although I was 6 months) seems to be fine now, but we'll see I am gunna take it up a few hills today.

 

I'll be doing a HG swap this weekend. Be sure to check the DIY!

 

thank you I'm going to try the hg test and definitely check the heating system... better to get the small stuff out of the way first

 

Had the same problem with mine. Replaced radiator, therm, water pump only 10k miles, no leak. Turned out that it was the head gasket releasing into the exhaust a very small amount. Does the temp guage fluctuate a lot? Mine would go from mid to hot no matter how I was driving.

 

yea mine is exaclty like that so the hg huh yea im guessing i have the same problem

 

Good info ITT thanks