1992 Honda Acura Lengend Overheats at Idle

If it stays cool "going down the road" and only heats up when stopped or at low speed, the problem is the radiator fan. The fan motor may be fine, but the relay is bad. Or something in the control circuit. You need to have it scanned and see if the temp sensor is being read. Toyota dealer can probably use their scanner to test the relay command

Thanks Gunny. We are replacing the relays today.

Semper Fidelis Marine

Gunny is right on target. If after changing the relays, you do not have the overheating resolved, look into finding a wiring diagram of the car. That should help solve it. Good luck.

There must also be a temp sensor that drives the relays......I suspect the temp sensor.....does the water temperature gauge function correctly? It may be the same sensor....

I have seen some engines that have high mileage and haven't always had the best of regular care, have a couple of cylinders that run hot due to build-up of sediment in the water jacket surrounding these cylinders. The sediment is caused by not changing the anti-freeze mixture, or often plain water, until it looks muddy and the rusty sediment precipitates out in areas of low turbulence. As the sediment accumulates, turbulence further decreases and sediment piles up to the point where cooling water can't get to the cylinder walls. This entire mass becomes a large heat source that, when at idle, the low coolant flow can't dissipate fast enough. At higher engine speeds and greater air flow through the radiator, enough cooling is provided.

Since water pumps usually pump water into the front of the engine block, the cylinders most affected are in the rear. An easy and cheap way to check is to knock out a freeze plug near the rear cylinders and poke around with a screwdriver. If a great deal is sediment is found, loosen it with the screwdriver and bent coat hanger and blast it out with a garden hose. Rubber expanding freeze plugs are about $5 each and are extremely simple to install, even if no sediment is found.

Using radiator flushes won't touch impacted sediment but are a good idea after digging it out. The good brands do remove a good bit of surface rust and scale and provide a better surface for heat transfer. In the past, I've found powdered Oxalic acid to work really well on heavy scale though it may not be compatible with todays engines that use a lot of plastics and aluminum. I would research it before using.

When working with cooling systems I first check the water pump as that is what moves the coolant. The pump can be turning but not pumping any liquids. Most water pumps stop pumping when air get in around the propeller area. Either from a bad seal or crack in the block, head gasket or ? It called cavitations this will as slow or stop your Boat in the water. After you have checked the pump and that is working then check the other components.

Electrical fans and relays are a pain at times. Please do a simple test to see if the fan is working. Find where the fan plugs into the electrical wiring. Unplug using test leads from the battery positive and negative test the fan . If and it should come on and run just fine. Tape the wires secure and start and run the engine. If the engine does not over heat you will know where the problem is. Then the problem is the relay and start looking. Relays are sometimes hard to find and easy to fix. The simplest way to find where the relay is you want is to go ask the auto dealer service shop.

There is an alternative you can use to get to the dealer or for driving out and about while trying to find the problem relay. By either leaving the test wires secure in place or running the wires into the driver compartment with a switch to turn the fan on and off as needed. You can even plug the factory wiring back in with your remote switch wires . Big trucks have an over ride switch to turn on the fan when the driver want. This should not be to hard to do as you are a home mechanic fixing a problem.

Last is if you have air conditioning in the auto or truck. When you turn it on the fan will come on. This is also the relay that is hook to the engine heat censor . It is possible to have more than one relay to the same cooling fan but not likely.

Good luck and sorry I did not go into details on how to do the wiring. The fan will turn either way so check the air flow to see if its pulling or pushing air.

Everett w.

Radiator fan relay or faulty connection in the wiring.

Coolant thermostat installed backwards (Have personnally witnessed this).

The litle sensing 'bulb' needs to face the engine when installed into the housing.

Cheers.

J.

Thanks for all the recommendations Guys.

We have determined that it was indeed a head gasket. Very small failure but enough to leak exhaust into cooling system.

Case Closed.

So, anyone need a project car?

Make sure you use an OEM thermostat, not a autozone type. Replace main fan relay, you should be good. Also bleed the cooloing system.

We refused to give up on it. The head gasket failure was really a failure of the mechanic to properly run the test.

So far we had replaced the radiator, fans, relays, thermostat, hoses and belt. Water pump checks out fine.

Final solution was to Flush the block and radiator again. Took out the radiator, and flow tested it again at a real radiator shop. Insufficient flow caused by blocked passages from poor quality welding/soldering. Got the manufacturer to replace the radiator (tested it first) and pay for half the parts and labor.

Car now runs great with no overheating, even in Phoenix.