Radiator Gauge

Hello I have a 1991 plymouth acclaim and here is the problem, when I take a long trip and reach speeds of 60 or more for any length of time, the Needle for the radiator moves up and down between low and high but NOT to Hot!
If I am driving around town it does not seem to do this, is this normal for the temperature guage to be eractic like that on an older car? I suspect dirt in the antifreeze, the thermostat was changed about 3 years ago! I checked the antifreeze reservoir and ratiator to see if it was unusually hot. seemed normal
Also, is there anyway to Test the thermostat to see if it is defeative? Thanks

 

You can put a thermostat in a bowl of hot water. You will need a thermometer to get the water hot enought to see if the thermostat opens up, usually around 135 degrees I believe.

Do a good coolant flush, replace the thermostat (cheap).

 

Just wondering...something tickled a brain cell...could it be air in the system as well? Dunno, just a random thought.

 

Ok, here is what I did, I drained all the antifreeze and it was filthy and had pieces of junk in it. So I then flushed it out with the hose, I did not use any Flush rust remover, after I filled it up again with plain water, I let it run for 15 minutes with the heater on full blast. But after 15 minutes, there was no heat just cold air, was I suppose to turn on the heater AFTER the 15 minutes were up? Or is there particles still in there, in which case should I get a Flushing agent will that disolve the particles? Right now it is sitting in the garage with the plain water in it still,. Any adise would be appreciated, Thanks, BTW, the thermostate worked perfectly before this and is only 3years old!

 

Filling it all with water is a no no. The longer you let the water sit there, the more likely you will/could have a corrosion problem.

Fill it with the proper ratio of coolant.

 

But the heater should be hot whether theres water or antifreeze in the radiator, isn't this True??

 

GungGuy, If it is air in the system how do I get it out? Thanks

 

sounds like air for sure...best way to bled air out of that system is raise the front of the car so the radiator cap is higher than the heater core....but before you go do that...that t-stat on the 2.2 2.5 engine are known to break.....not open funny break....break break....like one of the tabs that hold it togeather snap off so don't even think 3 years makes it ok....check it first....it's sounding like that is the deal.....if you don't lose heat in the cabin i would go with the t-stat

 

my theory is any time you remove a t-stat just replace it they are not that expensive, also gunguy yes it is probably air locked and some vehicles are easy to burp and some are not.
look for bleeder valves on different places on the engine when filling, some times you will need to loosen hoses to heater cores and use a thin blade screwdriver to insert between the hose and the pipeing to burp the air out, also as stated by itstheshark raising the front of the vehicle can help although front wheel drives don't work as well on this.
never leave just pure water in a modern engine due to corrosion problems.

here is a tool that works very well to help remove all air from modern cooling systems.
UView 550000 Airlift Cooling System Leak Checker and Airlock Purge Tool Kit

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