car getting hot at idle

[SAWYER]

01 Civic

when sitting idle it will get hot however if I rev the engine while idle is will cool down. It also gets back to normal when driving. Thermostat? Water pump?

 

[JulesMaximus]

I'd start with your cooling fan to see if it is kicking on when your engine is idling and up to temperature.

 

[phucheneh]

^ that. Kick the AC on and see if they spin. Assuming the AC works. If the compressor clutch engages but no fan(s) kick on, it's probably a fan motor, relay, or associated wiring. Check fuse first, then feel the relay and see if it clicks.

If the fans do operate, it's probably a bad fan switch (thermostatic switch, kicks relay on at a certain coolant temp). You can test the fan switch by disconnecting it and jumping the terminals. I think. On some cars, just unplugging it will turn the fans on. Toyota is usually like that, but I believe Honda is the opposite. Either way, you can't mess it up...there are two modes, on/off, and two switch positions, open/closed.

If revving the engine makes it cool down, though, that usually indicates a problem with coolant flow. Obviously, check to make sure there is coolant.

Assuming full coolant and no air pockets (Hondas are usually not bad about trapping air), I would say a bad water pump or a sticking thermostat.

Feel the upper radiator hose with the engine hot. If it's not pressurized (shouldn't be able to collapse it if you squeeze it by hand) or is not hot, that's gonna indicate some kind of flow problem. Thermostat closing when it shouldn't, or stuck partially open, or low output from the water pump (I've seen impellers corroded to nothing before, but it's not exactly common). Could also be as simple as a leak or a bad radiator cap, but you'd probably have noticed some coolant on the ground.

 

[Zenmervolt]

If revving the engine makes it cool down, though, that usually indicates a problem with coolant flow. Obviously, check to make sure there is coolant.

Assuming full coolant and no air pockets (Hondas are usually not bad about trapping air), I would say a bad water pump or a sticking thermostat.

Feel the upper radiator hose with the engine hot. If it's not pressurized (shouldn't be able to collapse it if you squeeze it by hand) or is not hot, that's gonna indicate some kind of flow problem. Thermostat closing when it shouldn't, or stuck partially open, or low output from the water pump (I've seen impellers corroded to nothing before, but it's not exactly common). Could also be as simple as a leak or a bad radiator cap, but you'd probably have noticed some coolant on the ground.

I agree with this. Usually if revving the engine makes the temperature fall, the issue is that there's not enough head pressure at idle. Could be a problem with the impeller, a trapped air pocket (as you note, this one isn't a normal Honda issue), could be either the impeller or the pulley of the water pump slipping on the shaft too.

I've also seen, though rare, small head gasket leaks that caused slow coolant loss without significant symptoms.

ZV

 

[ThatsABigOne]

You might have a big air pocket in your cooling system.

 

[SAWYER]

My fans are working and the top hose going into my radiator is getting hot

 

[NutBucket]

Are you low on coolant? When was the last time the timing belt was replaced?

 

[SAWYER]

I have never replaced it and out some coolant in a couple weeks ago

 

[KentState]

I would guess the water pump is starting to fail.

 

[NutBucket]

Or stuck thermostat.

OP does the top hoes get soft when the engine heats up or does it stay hard?

 

[SAWYER]

At normal temp I could still squeeze it but it was hot

 

[phucheneh]

At operating temp, you should not be able to make it deform much. A light squeeze will do pretty much nothing. Really putting some effort into it might result in, say, 25% deflection. As in, if it's a 2" hose, you shouldn't be able to push it in more than a quarter inch or so on either side. Hard to describe what 'feels' right, but that should give you a rough idea. If it's hot but you can make the sides of the hose almost touch, it's highly likely that the system is not holding pressure.

What's the lower hose like, in comparison?

Why did you add antifreeze? How much? It doesn't go anywhere on its own. Sounds like you have a leak.

 

[SAWYER]

The sides were not touching, I was just able to make it move in with a normal squeeze

 

[ino uno soweno]

Hey Sawyer,

Tricky prob with no answer as yet,

I would suggest more clues are required, so when you say, " it gets hot at idle", do you mean it boils if you do not rev it to cool it down, ??, or it just gets a little hotter and remains there,???,

Also could someone tell me what OP means, please.

 

[SAWYER]

The needle goes to red

 

[Zenmervolt]

Also could someone tell me what OP means, please.

http://www.acronymfinder.com/OP.html

It's on the top of the list. I've always found that site helpful. Even though it's just a list of all possible acronyms, it's always been enough to figure things out from context.

ZV

 

[ino uno soweno]

Hey Zenmervolt,

Thanks, yes, very so obvious, but the obviouse is often the hardest to see, I locked your link into bookmarks, excellent, you are a legend.

So was the futures and options link, I will read it soon, so it sinks in, real soon, thanks,

At Garage Youtube Group, link did not download, but I look forward to seeing it,

Quote.
The needle goes to red

I wonder how long it has been going to the red, and if you might say, " it has been doing this scince you last serviced it or changed to a after market thermostate, or radiator ", or something that might have caused the problem in the past, ??.

At this point there is not enough cooling at idle, but then you raise the rpm, and pressure, veloicity of water flow rises, perhaps a restriction when there is " not enough " pressure or water velocity, just guessing, I have not experienced this prob before,

Might be easier to just change the thermostate, but a hose calapsing is a very good chance too, definatly fits the problem, but I am still just guessing,

You might check the hoses for de-laminating, the inside the colapses and restricts while the outside does not leak, and look ok, the restriction is forced out of the way under pressure,???.

 

[SAWYER]

It just recently started doing this the past month maybe, I havent did anything new

 

[iamwiz82]

perhaps the water pump lost one of its impellers and isn't moving the correct amount of coolant now. The fact that it cools down when revved at idle is very strange.

EDIT: You just put coolant in? How much did it take?

 

[hanoverphist]

could be the water pump, or the radiator is clogged. id almost put money on the head gasket failing and pushing HC gas into the cooling system. mainly because i have an older civic and have had the issue before. try leaving the radiator cap turned halfway on and see if it goes away. make sure to fill the radiator if you do this, the water/ coolant will leak out.

best thing to do once you run through all the other trials is go to a shop and have the coolant tested for HC gases present. if there is, bad head gasket.

 

[BUTCH1]

could be the water pump, or the radiator is clogged. id almost put money on the head gasket failing and pushing HC gas into the cooling system. mainly because i have an older civic and have had the issue before. try leaving the radiator cap turned halfway on and see if it goes away. make sure to fill the radiator if you do this, the water/ coolant will leak out.

best thing to do once you run through all the other trials is go to a shop and have the coolant tested for HC gases present. if there is, bad head gasket.

I had a car that when at a stop light the fan would come on but it took a long time to notice the coolant temp drop, turns out the radiator was just to gummed up for good flow, since a new one was only $100 I swapped it out and all was fine. I think OP might be looking at the pump vanes being badly worn and not moving enough water@ idle to cool off the engine. Get it fixed soon OP, Honda makes as tough a 4 banger as they come but overheating aluminum is always a bad idea..

 

[kitatech]

If the engine doesn't overheat at the beginning, then the thermostat has opened, wouidn't you think?
If the fan goes on and they cool the temp when the car is stopped it could be the water pump or just maybe that the air flow through the front may be blocked by debris and the fan draws more air as the moving car does...check to see if there is dirt and debris on the front of the radiator...hopefully the solution is as simple as a hosing down...

 

[ino uno soweno]

Wow, I got on to a good Honda mechanic, I told him the problem, Civic 01, overheat at idle and normal under driving conditions, he immediately said " electrical idle control module ",
I would not know, but I think this guy is good, he says just get a second hand, it is rare that this happens, and a second hand mod usually fixes the problem for good, ,
I have also been ringing another guy, no success yet, but if he agrees, I think that will be your problem,
I will get back to you when I get on to him, and yes I should of thought of getting on to them from the beginning,

 

[Zenmervolt]

Wow, I got on to a good Honda mechanic, I told him the problem, Civic 01, overheat at idle and normal under driving conditions, he immediately said " electrical idle control module ",
I would not know, but I think this guy is good, he says just get a second hand, it is rare that this happens, and a second hand mod usually fixes the problem for good, ,

There is absolutely no possible way that the Idle Air Control Valve (the term used by Honda for that part; any decent Honda mechanic should call it that and not an "electrical idle control module") could cause overheating.

ZV

 

[BUTCH1]

There is absolutely no possible way that the Idle Air Control Valve (the term used by Honda for that part; any decent Honda mechanic should call it that and not an "electrical idle control module") could cause overheating.

ZV

Even IF the fan's activation were in some quirky tied to the IAC the OP has already verified the fan is coming on when called for, I'd hate to be that mechanic's customer!..