Topic: Running hot - 96 Accord

[Accordingly]

Hi guys, RE: 96 Honda Accord EX, 4 cyl. (not EX-R, VTEC) @ 320K

The car seems to be running hot, but only under specific circumstances. The temp reads in the normal range when on the road, but then shoots high after coming off the highway and entering city traffic.

In city traffic, the temp then varies from near normal to high, depending on whether the car is in motion (i.e. wind cooling effect?). Also, when idling at a light, the temp rises, but the fan does not turn on. However, when I turn off the ignition, the fan comes on straight away for a period of time.

Why would the fan remain off while at idle (with high temp) but then turn on after I turn off the ignition?

My mechanic suggests a new water pump and thermostat for $500. However, the water pump was changed with the timing belt at ~300K.

Thoughts? Thanks in advance...

[mrthompson]

Try a thermostat and rad cap.  Both are to be changed at the same time.

[Railton]

Try a thermostat and rad cap.  Both are to be changed at the same time.

Try to locate a Summer thermostate that will open sooner. You might think of replacing the rad as well - the current one is likely on it's last legs. They're not too expensive and depending on your ability and tools not too hard to replace.
Railton

[PJungnitsch]

I'd guess it is a problem with the sensor that controls the fan. On my Olds there was a temperature sensor screwed into the engine block that went bad and wouldn't send power to the fan when the water temperature heated up.

IIRC there was a simple test in the Haynes manual, probably first checking for power to the sensor, then checking all connections (sensor and fan), then putting the sensor in heated water of a certain temp while testing the contacts to see when it allows power flow (ohmmeter).

Anyway the sensor was cheap and replacing it was easy.

The alternative test would be to put the fan on a manual switch, turn it on when the temp goes up, and see if your problem goes away, I know some who have done that on motorcycles with sensor controlled electric fans as a permanent fix. Bit of a pain though.

[mrthompson]

Good call on the rad, Railton.  It can be difficult to determine the condition of a rad by visual inspection alone.  Now I remember that when I had an '85 Blazer that tended to overheat in conditions, I tried replacing the thermostat and other items.  The rad looked to be in serviceable condition, however that was not the case.  After replacing it, there were no more problems with overheating.  Running your heater on high to prevent a boil over on a humid July day is not fun.

[Accordingly]

Thanks for the thoughts so far.

The rad was replaced in October 06, so it is likely OK. The mechanic has now tested the fan and it is operating correctly; he feels poor coolant flow is the culprit. Hence, his recomendation for a new water pump (and to replace the thermostat while at it, I guess).

Perhaps I should have only authorized replacing the thermostat to rule that out, but I wasn't thinking diagnostically, I guess.

Anyway, will let youse know how it turns out. Its only money 

Cheers,

[mrthompson]

The heater core could be plugged.  My father had troubles with his Dodge Shadow overheating.  After a new head gasket, rad, water pump and thermostat the overheating persisted.  Another mechanic recommended that he have the cooling system flushed as the heater core could be blocked.  He went to a shop which specializes in this and it solved the overheating problem.  I think it cost around $40 for the flush job.

[barrie1]

If your anti-freeze is fairly new then I would also say Thermostat as thats the most often overlooked part in most engines. They open and close virtually thousands of times every year and the spring eventually loses its tension. Did one of my own cars last week as it was rather slow as well.  I could push the spring with my little finger which is the sign of a tired spring. That car runs as good as a new one now because of the change. 

[Accordingly]

Thanks Barrie...there is a new thermo in there now (as well as new antifreeze), so we'll see how that goes. Mr. T, I will keep the flush in mind if the overheating persists. Will highway test it tomorrow, which is where I had the trouble. Thanks.

[kmak]

If it was a Honda genuine part, then no way to the water pump.  Jobber, who knows.

Try thermostat first as you have done.  If the fans cycle after shut down, check the rad fan timer circuit ( I don't recall if the 96 Accords had one.)

Also, a poorly operating coolant fan switch can cause the same symptoms you describe.

All these items are fairly inexpensive and easy to change.

[barrie1]

I would suggest when it becomes time to flush the rad  put a large box of baking soda in the rad asnd drive it for a week 1st. Then do the flush as it will really clean any of the deposits out and just rinse with plenty of clear water afterwards. This will clean it out just as good if not better then the $40. -$50. flush at the garage instead.  

[articsteve]

Also, when idling at a light, the temp rises, but the fan does not turn on. However, when I turn off the ignition, the fan comes on straight away for a period of time.

Why would the fan remain off while at idle (with high temp) but then turn on after I turn off the ignition?

Fan relay or auxiliary fan switch located on the left of the rad's water outlet.

The car seems to be running hot, but only under specific circumstances. The temp reads in the normal range when on the road, but then shoots high after coming off the highway and entering city traffic.

Sounds like only your fan clutch is cooling the car, hence it's overwhelmed at stop lights.

[Accordingly]

Thanks Steve...what is the fan clutch? And what is amiss if it is overwhelmed?

[maritime_storm]

Their is no clutch fan on the car. Yes, change the water pump while they are changing the timing belt, if this is your problem or it is going to leak it will usually do it right after a belt change, it costs very little extra to do it at this time, and lot if you have to have it torn down a second time shortly after.

[articsteve]

Thanks Steve...what is the fan clutch? And what is amiss if it is overwhelmed?

FYI, fan clutches are mechanical radiator fans that run right off the rotation of the motor.  They were still around in the 90's, but are essentially phased out now.  My 95 Bimmer had both a fan clutch and an electric fan for the AC condenser.

I took a quick look at my parts finder and it came up with a clutch fan for the 96 Accord, but after looking more throughly I think your car, if it is without AC has only one electric fan to cool the rad.  This assembly includes the fan motor, the fan blade, and the shroud. On models w/o air cond., this is the only radiator fan. On models w/ air cond., this is the fan that is controlled by the coolant temp thermo-fan switch.

So is this Accord with or without AC?

With AC

This assembly includes the fan motor, fan blade, and fan shroud. This is the fan that is controlled by the air cond. system and not the fan that is controlled by the coolant temp thermo-fan switch.

I'm thinking that your cheapest bet is to replace the coolant temp thermo-fan switch.  There are two different ones unfortunately.  They sell for about $40. each and you should be able to do it yourself. Here is a pic.  One is located in the radiator return and the other is in the thermostat housing.  Try disconnecting one and if no change then that might be the offender.

[Accordingly]

Steve, I missed your reply and was then away on vacation. Sorry about my delayed response. Thanks for looking into this.

My Accord does have AC (can't live without it). I will look into your suggestion...seems simple enough to disconnect one and see what happens.

Thanks again. 

[articsteve]

My Accord does have AC

In many cars the condensor fan (AC) and the rad fan (engine) are both controlled by the "AC" relay.    You could try unplugging it and giving it a good tap or two and then reinstalling.

[Accordingly]

I think I better invest in a Chiltons if I want to keep this car any longer.