Thermostat gauge keeps going to hot?

[Bobknoblet]

My name is Rocky, I have a 1995 Subaru Legacy with a 2.2 eng. it started out by over heating. I put coolant in it and it seemed to be better. The next day I drove to work and I think it boiled over. I had some coolant on the ground. I changed the thermostat. The gauge still goes to hot, so I changed the temp sending unit. Well the gauge is still register hot, but the gauge now fluctuates from hot to normal? Any suggestion what it might be? The cooling fans are both working and coming on. The gauge will stay normal for several minutes?? The car has 375000 miles on it. But runs good.

[johnegg]

you probably have a cooling system leak.

once enough coolant leaks out it overheats.

 

re-filling helps,

but if not done correctly it can also cause overheating.

 

changing the t-stat was probably not necessary,

and if you used a cheap t-stat from the parts store it may now be causing it to heat up.

these cars do not like after market t-stats.

 

the temp sensor you replace probably was not needed,

but removing it let coolant flow back in to the engine block

bypassing any possible ''air lock''.

so operation improved, but was not perfect afterwards.

 

so i suggest you re-install the original or buy a new ''subaru'' t-stat from the dealer.

if you compare them side by side you will see a HUGE difference.

 

refill the cooling system based on the info in the following thread:

how to fill and burp your cooling system. - Subaru Legacy Forums

 

and then drive it and watch it closely.

 

check the level every morning before you drive, when the system is cold.

if you are losing coolant over a few days, you have a leak.

 

park over a piece of cardboard at night.

look for coolant on the cardboard. (ignore the oil spots for now)

 

let the car idle in your drive way , over cardboard, after you return home.

sometimes they only leak when at full operating temp.

 

if it over heats, look inside the over flow bottle, not the rad, and look for bubbles.

this could indicate bad head gaskets.

but if the system has not been filled correctly, it could just the air escaping.

 

at your age it would not be unusual for the rad to be clogged,

but you need to eliminate other stuff before you buy a rad.

 

you COULD have bad head gaskets,

but this is not common for the ej22,

not unheard of either.

 

but most likely you have a leak,

and the fixes you have employed have complicated the issue.

so you need to get back to a full working cooling system to diagnose the problem.

 

good luck.

[xdeadeye1]

yeah he probably got low from a small leak,, then let in a big air bubble into the system and now its still being hot,, and fluctuating..

 

You need to burp your system of the air bubble.