I have a91 honda accord 5 spd and have gone through the entire cooling system and still have a weird problem. I leave for work at 430am and i literally drive maybe 1/2 mile and the temp gage has already creeped up to full running temp. Yesterday coming home it got really hot right below the red line on the gage but when i pulled over to look there were no signs of it being hot. I just replaced water pump and put a factory oem honda thermostat in. So has anyone else experienced this? Im thinking the temp sending unit might be bad. Thanks for any help.

 

Did you open the bleed fitting when refilling the cooling system to remove all trapped air? Double check that radiator is full when the system is cold.

 

Was this happening before the work - wp and t-stat replacement?

There are some other questions but need to know the answer to mine before going foward.

 

To answer 9DEX first the radiator is full when car is cold and i did not take that bleed fitting out when fill so i guess there could be some air in the system. And poorman212 yes it did warm up within a half mile of driving from the day i bought it and it would get hot but cool right down. But now that im driving longer and farther its not cooling down until i am on a down hill or get off freeway according to the gage.

 

As suggested, check or re-bleed the cooling system.

When the temp gauge goes up, do BOTH fans come on? When you shut the car off and the gauge is at "hot" - does one fan kick on and run?

 

When i pulled over the first time i saw it get that hot both fans where running but its hard to hear them from inside the car so cant say there running every time for sure. The one fan does kick on after the car is shut off alot also. As far as bleeding the air do i just start the car an pull that fitting? And for how long?

 

Best way to bleed is while you are filling the cooling system. Make sure your heater is set to full hot to open the heater control valve to purge any air in the heater core.
You loosen the bleed fitting, but don't remove it. Now slowly add your 50/50 Honda brand coolant. As you are filling through the radiator, you will see partial coolant and air start to come out of the bleed fitting. Close the bleed screw after you see 100% coolant with no air mixed in. Now fill the radiator to the top. Leave the cap off.
Start the engine and let it run long enough for the cooling fan to come on twice. Add coolant as necessary to keep radiator full during this process. You will be able to see air bubbles being expelled at the filler neck.
Monitor your temp gauge and you can also insert a thermometer at the filler neck to see what the coolant temp actually is. Visually verify that you have good coolant flow/circulation through the radiator.
Be sure to add coolant to the recovery bottle to bring the level up to between the hot and cold marks.
Make sure your cap is functioning properly and that the seal is good.

My 90 accord also reaches full operating temp within the 1st mile with a oem honda t-stat. This is normal.

 

Ok i will do this and post results thanks for the info 9DEX.

 

One thing to add, don't get worried if some coolant pushes out of the rad as the engine is warming up......let it over flow....at some point (t-stat opens) it will drop. If it drops too much (you can see the row of "fins" inside the rad), add a bit of coolant

 

Ok i did everything we talked about above step by step and its still doing the same thing. I let the car idle 25-30 min and towards the end of that i put this digital heat gun i have on the open rad and got 174 degrees. And the fans came on a few times and i could tell when the t-stat opened, this is to weird.