idle temp issue

[emosun]

Its a 92 wagon. When the vehicle is idle the temp will slowly rise well above normal.

However , if it's at idle and I press the gas pedal the temp will immediately shoot back down. As if it isn't pumping water without the rpm's being higher.

This is an obvious problem if I plan to stop at traffic lights.

Fan works fine , drives fine , coolent is full.

somthing to do with the relation between when the pump is supposed to turn on and whatever is supposed to tell it to turn on....

[spiderpig]

Clogged water pump?????........

[emosun]

Keep in mind if i sit in the car in park and have my foot on the gas at 1300 rpms or higher , it'll sit there totally fine and cool. The pump seems to work , just not when it's supposed to.

[spiderpig]

The water pump is ran off a belt right? Could belt be missing it at idle but catching it when revving? Do you have a digital multimeter to check the ECTS?

[emosun]

I may be wrong but I'm pretty sure there isn't a water pump on a belt on cb7's. just AC power steering and alt.

[Fleetw00d]

The water pump is driven by the timing belt. When you say coolant is full, are you actually checking the radiator or just the overflow tank? My 90 was doing this and I kept looking at the overflow tank and it was about halfway where is should be. I finally checked the radiator and had to put at least half a gallon in (not sure where it's going). Temperature is steady again.

[emosun]

Should the radiator be full just below the cap when cold?

Yes , I also filled the overflow tank and notice the actual radiator wasn't full , I didn't wanna chance overfilling it.

[Fleetw00d]

Should the radiator be full just below the cap when cold?

Yes , I also filled the overflow tank and notice the actual radiator wasn't full , I didn't wanna chance overfilling it.

Ever get your problem figured out?

You can't overfill the radiator or overflow tank. The system is supposed to work to keep the radiator essentially full to the top. As the coolant and any air in the system heat up and expand, the pressure increases until it opens the valve on the radiator cap, allowing the air to be pushed to the overflow tank. It is introduced at the bottom of the tank so that it will then bubble up to the top. After shutting your engine off, when the system cools, the coolant and what little air is in the system contract, resulting in a lower pressure than atmospheric, so it sucks coolant from the bottom of the overflow tank back in to the radiator. This is how the system purges air and keeps the system full of coolant.

If you "overfill" the radiator, it flows out before you put the cap on. If you overfill the overflow tank, as the system heats up and pushes coolant out of the radiator, it will simply push some coolant out the vent at the top of the overflow tank. To avoid wasting coolant, there is a "Full Hot" line about half way up the overflow tank. This permits a certain volume to accommodate the amount of coolant pushed out of a hot engine, then sucked back in when it cools.

I am now experiencing a similar problem on a 92 EX coupe I just bought. It was running hot when I got it. I checked the thermostat and swear it was in backwards; so I installed it correctly and it seemed fine while driving it, but when I got home, the temperature slowly climbed. Tonight I installed a Honda thermostat, filled, and bled the system (I've found bleeding works best if you raise the front of the car). I started it, let it idle for a while; the temperature came up, but fans never turned on. I took it to pick up pizza, idled for several minutes at the pick up window, temperature held normal and steady. When I got home and stopped, the hose temperatures were in the 180 range. The temperature again slowly climbed to the top of the gage. My infrared thermometer showed both upper and lower hoses only in the 190 F range. I found the ECT A switch connector undone; connected that, then the fans would kick on as the needle climbed to about 3/4 up, but the hoses were still only in the 190-200 range. I guess I don't believe it is the gage because it appears to read correctly when I'm driving. How can the temperature sensor see such a different temperature?