Overheating...kinda

techy101 · #1 09-24-2007, 09:10 PM

I swapped radiators out today with one from the junk yard, and replaced the cap with a new one. My old one had a small crack, and the cap was shot.

Anyway, since this swap the car's acting real funny. It will heat way way up, get near red, then randomly fall back down to normal. It seems to like to get real hot if I'm being gentle, but if I gun it it seems to cool right down (even if I'm not going fast). Gunning it at a stop in neutral will also seem to have the same effect.

My guess on the issue is a sticking thermostat. Anyone else have an idea??

I'm thinking that there was either something that broke loose from the "new" radiator and is gooping up the thermostat, or it didn't show for some reason because the old radiator couldn't really build up pressure.

It's Just Eric · #2 09-24-2007, 09:30 PM

probably.

Could also be some air bubbles in the coolant from when you refilled it, but knowing the amount of work you've done to the car already, I think "You filled it wrong" is a little less likely than "There's crap in it"

Always worth a check though

techy101 · #3 09-24-2007, 09:31 PM

For giggles... how would one check to make sure that there aren't lots of bubbles in the coolant? (I never put "I did it wrong" out of the question. Seems like every time I do that's when it seems to be the cause.)

YourConfused · #4 09-24-2007, 10:30 PM

air in system #1
worn impeller on water pump #2
that's that's all the logical and easy ansswers I can think of.

budbaer · #5 09-24-2007, 10:35 PM

-make sure you car is on level ground
-remove the cap, while it's cool.
-start the car
-turn on the heater, with the temp turned up to 85 and the fan on high
-let the car run till it reaches normal running temp
-top off with antifreeze
-replace cap
-ENJOY

Sorry if this is too elementary of an explanation.

techy101 · #6 09-24-2007, 10:52 PM

Quote:

Originally Posted by YourConfused

air in system #1
worn impeller on water pump #2
that's that's all the logical and easy ansswers I can think of.

Water pump was replaced with new one just a few months ago.

Hocrest · #7 09-24-2007, 10:56 PM

Quote:

Originally Posted by techy101

It will heat way way up, get near red, then randomly fall back down to normal. It seems to like to get real hot if I'm being gentle, but if I gun it it seems to cool right down (even if I'm not going fast).

Did you reconnect the fans? Are they running when the car is not moving and the gauge goes above 1/2??

If your car is moving constantly you don't need fans, when it's sitting still they are very necessary.

techy101 · #8 09-24-2007, 10:58 PM

Quote:

Originally Posted by Hocrest

Did you reconnect the fans? Are they running when the car is not moving and the gauge goes above 1/2??

If your car is moving constantly you don't need fans, when it's sitting still they are very necessary.

Yup, that was the first thing I double checked. Fans are kicking on right on cue.

svxpert · #9 09-24-2007, 11:00 PM

<<For giggles... how would one check to make sure that there aren't lots of bubbles in the coolant? (I never put "I did it wrong" out of the question. Seems like every time I do that's when it seems to be the cause.)>>

telling us how you filled the newer radiator will determine if air trapped in the system is the problem.

techy101 · #10 09-24-2007, 11:02 PM

Quote:

Originally Posted by svxpert

<<For giggles... how would one check to make sure that there aren't lots of bubbles in the coolant? (I never put "I did it wrong" out of the question. Seems like every time I do that's when it seems to be the cause.)>>

telling us how you filled the newer radiator will determine if air trapped in the system is the problem.

I filled up the radiator first, once it was full up, went over to the tank, filled it up to Full, ran the system until hot, let it cool down, topped off the radiator and the tank.

Speedklix · #11 09-24-2007, 11:12 PM

if the heat was not on full blast though for some time, then there could be air in the heater core. when I refill the SVX it ussually has to breath some fluid in and out of the tank a few times untill the air works all the way out

sometimes I start the car cold with the heat on full blast with the cap off and rad filled and wait for it to go down, and add mixed fluid as it goes down, once it is done accepting fluid I add a little to the res and shut it off.
I use a similar procedure at the garage, only ther is a funnel like device that replaces the cap

svxpert · #12 09-25-2007, 10:36 AM

<<I filled up the radiator first, once it was full up, went over to the tank, filled it up to Full, ran the system until hot, let it cool down, topped off the radiator and the tank.>>

thats the problem. you have to fill the engine block first, then fill the radiator the rest.

techy101 · #13 09-25-2007, 09:06 PM

Well seems that you all were right. Apparently I fail at refilling coolant. It was still way low. So after filling it all up as you guys said, everything works perfectly!

Thanks!

YourConfused · #14 09-25-2007, 09:51 PM

I forget that not everyone has a spill-free funnel to attach to the radiator. they are super nice and everyone should get one.

NiftySVX · #15 09-26-2007, 02:37 PM

Filling coolant to a subaru can be tricky. I like to actually pour coolant into the upper radiator hose until it is full and then fill the radiator, with the coolant funnel. Don't feel bad, I did the same thing on my legacy the first time I changed coolant in it.