Strange Heater Behavior...

Just got back from 2wks overseas on Tues and noticed something strange. On Wed I went for a drive and noticed that my EGT gauge alarmed a couple of times. At the time I thought nothing of it cause I thought I may have recently reset the alarm when I disconnected the battery, didn't spend any more time thinking about it. However, yesterday I drove to work and noticed my heat wasn't working right... If I would stop at a light, the heat would go away (turned cold) until I accelerated away. This happened every time I stopped to wait for a light. Then I noticed that my engine temp would rise after I started going again, but not every time (may be related to how long I was stopped at the light). I then started thinking about the EGT alarm and realized it happened as I was accelerating away from a stop. Relationship? The EGT temp delta was ~50F from where it normally runs under load (1425 vs 1375). I started to think the EGT was real....

Now, what is wrong is the obvious question. First I was thinking thermostat, but can the behavior be explained by that? This morning I came up with another theory, the water pump. Could that lead to these symptoms?

Anybody have any suggestions or experience with this?

Thanks.

 

coolant level? year make model?

 

head gaskets??

 

Naaa..not a head gasket..you would smell coolant through your vents...if you are still worried its a head gasket do a leak down or test for exhaust gas in your coolant lines.

I would imagine it may be a shot thermostat? If it was your water pump you wouldn't be going cold so fast so it's not your water pump...not in this slackers opinion anyways.

I would check your thermostat...remember, start small and work your way up..usually the simplest thing is the biggest problem.

If it isn't your thermo let me know and we will continue trouble shooting Won't take long to track down the problem.

 

Oops... 04 STi. Haven't checked the level in a couple of months...will do that at lunch.

 

Could this be related to the fans? I wouldn't think so, but I am trying to understand why there is no problem while the engine is under load....

Thanks.

 

head gaskets can (and do alot) leak internally, where you wont smell them at all

 

i doubt it. if the fans arnt working you will over heat at idle, and have some wicked heat through the vents.

+1 on coolant level

 

yeah.. and throught he vents is usually heater core issue... trust me.. doing mine tonight... ha ha ha

 

Coolant is just below the low level line in the overflow tank, cold engine. I will add coolant, but do you think that little difference could lead to this behavior? I would hate to put more in, just to have to drain it again this weekend...

Thanks again...

 

no, if its cold and its on the low then its where it is supposed to be.

 

The water pump on my old car was going out and it wouldn't throw heat unless I was moving/in the revs. I've never heard of that happening before that tho.

 

Well, looks like I will start by changing my thermostat this weekend... Anybody know who takes used coolant?

 

the ground , i kid i kid, most auto parts stores will take it, i think!

 

So, I got out of work too late to make it to the parts counter before closing on Fri...Burnsville Subaru lists being open on Sat, but I find out that is an error...no time tonight...looks like I will hope for tomorrow.

I also realized something else over the weekend. It now sounds like I am spinning a supercharger all the time, although not real obvious unless you listen closely. I opened the hood and as it idled, I could hear what sounded like a bad bearing. I tracked it down to near the tensioner pulley. The belt appeared ok. Seems like an awfully strange coincidence that it went out at the same time. Any ideas if that could be related?

Thanks.

Christian

 

your water pump could be on its way out, that could explain the heating issue, is it leaking at all?

 

No leaking... The noise didn't seem to emanate from the water pump, but maybe it really is? Hmmm... I need to get the RS out of the back garage so I can look closer (heated garage).

 

So, I am starting to think this is the water pump going.... After doing a little research, I see that the pump is right under the idler pulley and that is where the sound appears to be emanating. I am going to look closer tonight...

Anyone know what it would cost to have this replaced (and might as well do the timing belt, as well)? I don't see that I will have the time to do such an extensive project as tonight is my only free time until the end of next week.

Thanks.

 

Well, all is now good... A buddy suggested removing the belt to see if the noise went away (why didn't I think of that?!)...it did. So, I have now replaced the idler pulley and the t-stat and all appears to be good. Thanks to everyone that offered help and suggestions.

Still surprised I had two idependent issues at the exact same time...

Christian