I am new to this forum but need some help with my Honda
I am driving a 93 Honda Accord and it has been having overheating issues.
When I drive it down the road it is fine and the temp is normal, but when ever I would stop at a stop light it would jump to about 3/4 of the way almost instantly and slowly climb. Then as soon as I started driving it would drop down to a little under half and stay the whole time I was driving.
A friend told me to check the cooling fan system. I checked the fan and the relay by shorting the plug that goes into the cooling fan switch (located at the thermostat housing) buy using a paperclip. It worked and the fans came on, so I changed the switch but it still would heat up when I stopped.
I took it to a mechanic and he said it was the radiator. So he flushed it and gave it back to me, it did nothing.
He then told me that I should change the whole radiator. My knowledge of cars is pretty limited to I did what he said and changed the radiator and the thermostat. Still does the same thing.
But lately I have noticed something that leads me to think it might be an electrical problem.
When I slow down, or even if I'm driving, if I do things like turn on the brights or roll down the windows the temperature gauge jumps up about a quarter of the way instantly. If I stop it still heats up, but if I do anything electrical, like even my blinker, the temp gauge jumps up even higher instantly.

Any thoughts? I am kinda at a loss here.

 

Make sure both cooling fans are running when temp gauge shows overheat condition. Intermittent cooling fans is possible due to faulty relays or fan motors.

You may have a faulty temp sensor that is cracked causing an intermittent response. ECT is very inexpensive and probably cheapest route is to replace and see if problem is resolved.

If you have a IR temp gun you could check whether temps are normal when fully warmed, usually about 195F is normal.

Unusually large voltage changes might also cause the immediate jump in temp indication. Suggest having alternator checked for normal voltage; 13-14.5 typically.

good luck

 

I'm very suspicious about the gauge jumping suddenly when you use electrical loads. Ground loops, electrical problems, things like that can cause errors in the gauge readings.

It's not possible for the actual temperature to change instantaneously. That has to happen over the course of a minute or probably much slower.

And with Honda, the normal position of the gauge needle is about 40% when you're driving down the road. Plenty of air is pushed through the radiator by the car's motion. When you stop for a long time (or block the air from the radiator), the gauge will climb above 50%, maybe even to 65% before the fans switch on. When they switch on, the temperature drops down & the cycle repeats itself. So don't freak out when it behaves like that. It should not approach the red zone at the top of the gauge.

 

Ok, yes maybe I will try to replace the ECT Sensor. Where is that located? Whenever I try to look it up everything shows me pictures of the fan cooling switch in the thermostat housing, not the temp gauge.
I'll have to see if I can borrow a temp gun from someone.
And I have a voltmeter so I'll test the alternator.

 

I believe it is under and forward of the distributor. Look in electrical under gauge panel for details. It's a single wire (red in 94 manual I have) harness and connector.

good luck

 

From: What are all the different "water-temperature sensors"?

 

If the gauge suddenly jumps up that could be caused by a flaky sender (the 1-wire sender) or by the wire being rubbed through the insulation & occasionally shorting to ground. Check out the wire before getting a new sender. (This one isn't very expensive, but I like to rule out wiring problems first)

 

As stated above. I think once you verify if the motor is actually getting hot you'll know what direction to head. I'm assuming you have checked coolant level so there's no air pocket and whatnot.

 

I had almost the exact same problem with my '90 Accord after I changed the radiator. Turned out the problem was air in the cooling system, all I had to do to fix it was use the cooling system bleeder valve to bleed out the air. There are some good videos on youtube that show where it is and how to use it.