Engine Cooloing Question...

OK, Temp guage wasn't working (would move off 'c' a little and no further) so I started to diagnos the problem. Started by trying to ground the temp sending unit wire. Once I did the needle went right up to 'H'.

I replaced the temp sending unit. As long as I was dirty I removed the thermostat to make sure it worked, (did as described in FSM), checked out OK. Put everything back together w/ new gasket and...

..my guage now works, works so well that it creeps slowly all the way up to the 'H'.


Now, whats causing this? Is it possible that there are air bubbles and the coolant isn't flowing properly? How would I know and how do I fix? Any other thoughts?

PS-must have Jeep drive "fix" soon, going through DTs.

 

a new t/stat can be very "active"
a 180* won't be fully open till about 190 - 195
you may see the needle go up until the t/stat opens
then it should fall back down
with cap off, you should see coolant circulating when the t/stat opens
yes it's possible there could be an air pocket

 

how does the internals of your radiator look? it might be clogged with scaling and material build up. you can run the engine with the radiator cap off to help purge the system of air.

 

Isn't that what the radiator overflow hose is for? :?

 

No the cap requires a preset anount of pressure to allow it to open and let excess antifreeze pypass into the overflow bottle. Sounds to me like it might be a problem with amount of flow. Check the radiator as described before and check your ignition timing. Wrong timing can cause excess heat as well, but I would bet on radiator.

 

Don't necessarily assume that a new thermostat is 'good'. If it acts weird, test it with hot water (I do it in the kitchen w/the microwave), and a candy thermometer. I wouldn't keep a thermostat that didn't open smoothly.

Use the candy thermometer to check the water temp in the radiator. Find specs (ohms) for the sender. Use hot water, candy thermometer and multimeter (ohmmeter).

 

gauge could be bad also. check temp w/known good one.

 

I'm gonna check the timing today hopfully and hook up a different gauge as a test. Thanks for all the responses

 

Will a mechanical temp gauge read different/lower than an electrical gauge? I hooked up a mechanical guage and I could see where what I thaught was a 190* thermostat opened at about 165-170*. The temp dropped alittle then leveled off at 170*. And the timing looked on so...