Engine overheating at idle

[InflatableBuddha]

The last couple of days, my 92 Accord (Auto, 136,000 km) has had the engine overheat (almost into the danger zone) when idling and driving at low speeds. Once I'm above 20km/h, the temperature drops to normal.

I'm taking it in tomorrow, and the mechanic is going to call me once he's examined it. He says he's going to look at the radiator and water pump first and then look at internal components (head gasket etc.) last.

What sort of problems could I expect, and how much can I expect repairs to be? I just want to have an idea for when the mechanic calls.

Thanks.

 

[BassBomb]

Is the rad fan activating?

Also, drive with AC on to force the rad fan to activate if possible

 

[zoiks]

Prob the fan as BB above indicates. I had the same problem with my old 240sx and the fan clutch was the culprit. Your car may have an electric fan however.
Prepare to get raped by the dealer though.

 

[InflatableBuddha]

Actually I have been driving with the A/C on recently - it's been warm enough that I've had to.

Also, this car has a feature where the radiator fan runs for a few minutes after switching the ignition off - that's normal according to the manual.

I'm not exactly expecting it to be cheap, but I don't have much car knowledge so I have to take it in. They're a respectable dealership though, and I've taken my car there before.

zoiks - if the fan clutch is the problem, what does that cost to replace?

 

[darom]

Was your water pump leaking?

Have you replaced a thermostat in your car? If it doesn't open, it might cause overheating condition you've described. Cheap part to fix.

 

[thomsbrain]

Your car does not have a fan clutch. It has electric fans. That's how they are able to turn on after the car is switched off. If they turn on at all, they are working.

If this only happens at idle and your fans are operating and your coolant level is good, my suspicion is the thermostat. I replaced a couple thermostats during my 91 Accord ownership. (or rather the mechanic replaced them). Should cost a couple hundred bucks installed.

Radiator and water pump problems would probably cause overheating at any speed, not just idle.

 

[radioouman]

If you have a leak in the cooling system and have pulled air in, air will get trapped at the top of the engine and cause the engine to overheat when the car is idling. A bad head gasket can also cause this.

 

[InflatableBuddha]

Originally posted by: thomsbrain
Your car does not have a fan clutch. It has electric fans. That's how they are able to turn on after the car is switched off. If they turn on at all, they are working.

If this only happens at idle and your fans are operating and your coolant level is good, my suspicion is the thermostat. I replaced a couple thermostats during my 91 Accord ownership. (or rather the mechanic replaced them). Should cost a couple hundred bucks installed.

Radiator and water pump problems would probably cause overheating at any speed, not just idle.

Thanks. I'll have the mechanic take a look at the themostat.

 

[exdeath]

If it's only overheating while stopped, but fine at all other times while moving, it's going to be the fan, fan relay, or fan temperature switch. Any other problems , such as poor circulation from air bubbles or bad thermostat would manifest while moving as well. If the wax has leaked out of the thermostat or it's corroded shut, you would be overheating all the time, as circulation to the radiator would be completely cut off, regardless of movement.

 

[DrGreen2007]

"I replaced a couple thermostats during my 91 Accord ownership. (or rather the mechanic replaced them). Should cost a couple hundred bucks installed"

a few hundred bucks to replace a $20 or less part?

 

[SparkyJJO]

Originally posted by: DrGreen2007
"I replaced a couple thermostats during my 91 Accord ownership. (or rather the mechanic replaced them). Should cost a couple hundred bucks installed"

a few hundred bucks to replace a $20 or less part?

That's what I was gonna say... I mean, crap, I know imports generally cost more to fix stuff, but 200 bucks is like

 

[herm0016]

my thermostat only cost me about 12 bucks, and took about 5 min to install.

sounds like a fan issue to me, just had to replace the relay and temp. sensor in my T/A so that the fan would come on. it would be fine at idle for a few min, but anything else would overheat it quickly

 

[brblx]

Originally posted by: thomsbrain
Your car does not have a fan clutch. It has electric fans. That's how they are able to turn on after the car is switched off. If they turn on at all, they are working.

not always. if the fan has multiple speeds, it could have something like a bad relay preventing it from working at just high or just low speed.

bad thermostat also usually is more of a problem under load, rarely when idling, and driving won't make it better. sounds 100% like the fan to me.

 

[InflatableBuddha]

Originally posted by: brblx

Originally posted by: thomsbrain
Your car does not have a fan clutch. It has electric fans. That's how they are able to turn on after the car is switched off. If they turn on at all, they are working.

not always. if the fan has multiple speeds, it could have something like a bad relay preventing it from working at just high or just low speed.

bad thermostat also usually is more of a problem under load, rarely when idling, and driving won't make it better. sounds 100% like the fan to me.

Yes, as I mentioned, it's only a problem when idling or at very low speeds, so the fan sounds very plausible. I'll have the mechanic check the fan-related relays and sensors too.

Thanks everyone, and I'll post back tomorrow with the results.

 

[brblx]

have you not just checked to see if the fan is running?

start car, turn AC on. if the fan's not running, it's probably the fan motor or a relay.

 

[DivideBYZero]

No one's asked it yet, so I will. Have you checked the coolant level?

 

[slag]

Originally posted by: DivideBYZero
No one's asked it yet, so I will. Have you checked the coolant level?

Thank You!!

I just saw this thread and this was the first thing that popped into my head.

Basic troubleshooting. Check coolant level, check to see if the fan is running, with the heater on, does it blow warm or hot air?

simple stuff first....

I've never seen an electric radiator fan have multiple speeds either. Guess its possible, but unlikely. Either it works or it doesnt.

 

[LTC8K6]

All of the cars I own have electric fans with multiple speeds.

On many cars, if you unplug the coolant sensor that the fan circuit is using, the fan will default to max speed. This will be a much higher speed than it ever normally runs.

 

[bruceb]

Your radiator may need to be flushed and fresh coolant put in. But that sounds like a weak water pump to me. As to multiple speeds on fans, depends on how the car is set up. On my GM 1999 there are 2 fans, one comes on for normal cooling when water gets to about 205 degrees.
Both are on when the AC is being used.

 

[radioouman]

Could be a corroded radiator too. Radiators do get plugged up on the inside from corrosion.

 

[exar333]

Originally posted by: DivideBYZero
No one's asked it yet, so I will. Have you checked the coolant level?

+1. My old car had head gasket issues and the coolant would leak, causing heat issues when sitting still.

 

[Jugernot]

Originally posted by: DrGreen2007
"I replaced a couple thermostats during my 91 Accord ownership. (or rather the mechanic replaced them). Should cost a couple hundred bucks installed"

a few hundred bucks to replace a $20 or less part?

Let's use your logic with a head gasket. Just because a part is cheap, doesn't mean it's not expensive to replace. Though a thermostat is cheap to replace...

 

[zoiks]

Originally posted by: Jugernot

Originally posted by: DrGreen2007
"I replaced a couple thermostats during my 91 Accord ownership. (or rather the mechanic replaced them). Should cost a couple hundred bucks installed"

a few hundred bucks to replace a $20 or less part?

Let's use your logic with a head gasket. Just because a part is cheap, doesn't mean it's not expensive to replace. Though a thermostat is cheap to replace...

Might be cheaper to replace on a Honda. On my 240sx, the thermostat was underneath the water pump pulley which was a bitch even for the mechanic to replace. Since the fan is driven using a pulley, the fan shroud, water pump and the fan needed to be removed to make space. It took him about a couple of hours to finish the job.
$200 doesn't sound far fetched for some cars.

 

[InflatableBuddha]

Originally posted by: slag

Originally posted by: DivideBYZero
No one's asked it yet, so I will. Have you checked the coolant level?

Thank You!!

I just saw this thread and this was the first thing that popped into my head.

Basic troubleshooting. Check coolant level, check to see if the fan is running, with the heater on, does it blow warm or hot air?

simple stuff first....

I've never seen an electric radiator fan have multiple speeds either. Guess its possible, but unlikely. Either it works or it doesnt.

The fan does work - I'm pretty sure I mentioned that earlier in the thread.

I looked under the hood with the mechanic when I dropped it off this morning - the coolant was indeed low. He said they would flush it, put fresh coolant in and run a pressure test.

He just called a few minutes ago to say that the water pump is leaking and needs to be replaced. I also need a new thermostat, heater hose and distributor o-ring. Parts, labour and taxes all-in - about $900 CAD. Holy fuck .

Well, at least this will give me a bit more life on this car.

 

[InflatableBuddha]

Originally posted by: bruceb
Your radiator may need to be flushed and fresh coolant put in. But that sounds like a weak water pump to me. As to multiple speeds on fans, depends on how the car is set up. On my GM 1999 there are 2 fans, one comes on for normal cooling when water gets to about 205 degrees.
Both are on when the AC is being used.

Yep, you were right about that.