Thermostat gauge fluctuating today in this hot weather :(

So its 96 Degrees here in Fl like it has been the past two months, but today my thermostat temp. was fluctuating like crazy.

 

I noticed it when I was parked with the a/c cranking at idle for no more than 7 minutes and my temp gauge was sitting just under notch right before the "red zone". I started to drive in stop and go traffic and the needle would pretty much bounce. While im driving 40+ mph, it would drop to its normal operating temp that I usually see (which is right before the 1/2 way mark). When I'm stopped, the needle would get to that high notch again. It never hits the red zone but this was defiantly unusual. I checked and I was still topped off with coolant.

 

I had a rad flush does less than 2k miles with Subaru coolant along with my T-belt job ( I'm at 106k stage 2) However I never changed my Thermostat in the water pump housing.

 

I'm thinking my radiator is giving up on me, so I'll probably replace it, but I want something that's a little larger, any Idea's ? I've seen a Mishimoto for $255

I already going to put a thermostat on order.

^

sounds like your radiator fans might not be turning on, according to your description, only goes up at idle but while driving it goes to normal mark, air flow problem at idle, check your relays then go from there, i believe i also saw something on here before about a problem on these cars about the radiator fans

It sounds like the fans.

 

A magic radiator will not help this at all and is not necessary.

What about synthetic oil? Will that help?

http://legacygt.com/forums/showthread.php/cooling-fan-relay-issue-now-recall-campaign-55332.html?t=55332&highlight=radiator+fans. This is the thread about the cooling fan issue and synthetic oil won't help its still going to require the cooling fans to work

I was being facetious.

I was being facetious.

my bad, you actually had me fooled

If you stick around for a while, you'll get it. Search the forum for rao + oil and you'll see what I'm talking about.

I thought synthetic oils reduced operating temperatures, is this not true?

Only the ones that you can't buy off the shelf.

Thanks for the replies. today was the second time the temp. guage was fluctuating like before, in hot weather. I totally forgot about the rad fans and I haven't checked the relays/ fuses but I have heard them turn on. Maybe only one is functioning ? Anyhow I did get the Mishimoto radiator/ thermostat since the car does have 100k miles, I figured why not.

 

Oh yea, my car has been serviced for that relay issue in the early years.

As I see it - the main reasons for the temperature to go wild is one of the following:

 

• Dirt (like dandelion seeds or similar) in the cooling fins of the radiator - flush from the backside with a garden hose.
  
• The thermostat. (Either it's bad or someone did mount a thermostat with a higher temperature than specified, which may be useful in areas with severe winter conditions)
  
• The fan(s).
  
• Bad head gasket or cylinder head.
  
• Bad water pump.
  
• Bad temp sensor. (do a separate measurement of engine temp to figure out this one)
  

And also - if you have something constricting the incoming air flow to the front side of the radiator. Stuff covering the opening below the bumper can make a large difference.

 

Also see: http://legacygt.com/forums/showthread.php/dont-pinch-off-heater-core-hose-167523.html

A bad flow through the heater core can also cause problems.

2004 wrx rad is the same but twice as thick.

So I went at it today installing the new rad ( btw this thing is huge !)

 

turns out the fan on the driver side was disconnected, not sure how, but it was.

 

I wanted to install my new thermostat but I couldn't get the 10mm bolt on top of the housing off, the bolt has been stripped and it's hard to get a grip. So I'll have to find another day for that...