temp gauge is all over the place

[wishiwerefishn]

i have a 94 xlt and the temp gauge keeps climing very high and very fast after even a short acceleration and then goes down after a few seconds. Not sure why. I already changed the thermostat but that did not solve the problem. Any suggestions or ideas?:roll:

 

[boggs1227]

do you have to correct mix in it ? have you flushed the system latelly ? did you burp out all the air in the system ? what range stat did you install ?

 

[mikeinri]

What he said...

If all the air is out, I would replace (or at least check) the sending unit. That's the most likely cause.

If that doesn't do it, could be the gauge or a wiring problem.

Hope this helps.

Mike

 

[mcelwajy]

I had the exact same issue on an old dodge years ago. Ended up being the sending unit and coolant temp sensor....

 

[boggs1227]

could be the sensor but when mine went out it made the guage read cold all the time .one easy test for this is to take the wire thats on the sensor off and touch it to the engine "grounding it" go back inside the truck turn on the key and if you see the guage go to it's fullest mark then you have ruled out the guage being bad ...sorry i don't know the volt readings for testing the sensor it's self ....should be in the haynes manual for that data .

 

[pugsy]

Mine does that as well to a certain degree. Sometimes you can tell when the t-stat closes up and the temp rises a bit, then you see it go down when the t-stat opens again. I'm guessing it's prolly just a cheap t-stat, or like others said, the sending unit. But as long as it doesn't overheat, I wouldn't worry about it.

 

[rocco123]

My '94 still does this even after replacing the thermostat. Not only indicatin, but it does seem to get cooler & hotter from the air vents. I plan on changing the thermostat again with a "Stant" brand if I can find one around here.

 

[wishiwerefishn]

thanks

thanks guys ill check that and let u know how it plays out.:roll:

 

[alphamale]

temp Rise

I had the same problem. I took upper rad hose off to see if I had flow of coolant to the radiator. I replaced t-stat thinking it could be faulty. The problem still exsited. Thought water pump went bad. I pulled old water pump off and ran a garden hose in each side of outlet port where the water pump mounts to and ran high pressure water until all air was blown out of block. Bigggggg air pocket in the block. After installing a new water pump and adding correct mixture my rig runs cool like its supposed to. Another way to tell is if one hose is hotter then the other its a preatty good indication the t-stat is not functioning properly or their may be an airpocket. I drove on it like that for almost a year thinking it was an air pocket and just needed to burb. Drove me nuts especially on the trails. The vehicle ran hotter than it was supposed to.

Hope this helps

 

[fixxxer]

If after burping the system, it still jumps around like that, it could be the waterpump, the impeller blades will eventually disintegrate. Does anything look like there is rust in the system or overflow tank?

 

[rocco123]

I still have that fluctuation in temp after changing the thermostat & intake manifold gasket duue to the intake gasket blowing out. I cleaned & flushed it with a flush kit too. Wonder if the pump is going? One thing I did notice was that when draining the cleaner / water mix out I thought the eng was up to temp, but the water that was draining was started to come out cool & then after about 1/2 gallon drained it was steaming hot. Radiator is 2 months old (replaced due to a leak). Heater core is about 3-4 years old. Still have a temp fluctuation.