Ok, have an odd issue for someone to solve.

 

1998 Legacy OWB 2.5

Issue is that yesterday I was out waiting to pick up my roomate from work and needed to warm up. So I fired her up and noticed the heat wasn't blowing out very warm, yet the engine was still close to normal temp at the time. I first thought my new t-stat went bad until I brought the RPM's up and the heat improved. the drive home was more than warm enough.

One other thing I noticed is that she likes to run 3/4 on the thermometer when I am at an idle but when I either increase the rpm's at an idle or get moving past about 35 mph. Not over heating issues any other time.

 

Thoughts?

check fluid level.

when it's warmed up - are the fans turning on?

 

radiator is probably partially clogged but check simple stuff first

radiatorbarn.com has cheap new rads.

heat not hot=low coolant level.

 

is the overflow full. This would be from coolant being pushed out.

 

look for bubbles in the overflow when running. If they are present, this is your problem.

 

indicative of a head gasket failure.

 

every other post is a cooling issue with a 97/98 legacy it seems

heat not hot=low coolant level.

 

is the overflow full. This would be from coolant being pushed out.

 

look for bubbles in the overflow when running. If they are present, this is your problem.

 

indicative of a head gasket failure.

 

every other post is a cooling issue with a 97/98 legacy it seems

 

Why 97/98 legacy?

From 1997 to about 2002 every auto mfg had at least one engine with some sort of Head Gasket issue (including harley). The emissions standards changed and there was not enough time for real world testing of engines so they were forced to cross thier fingers and hope.

 

Dodge neons had a 80 + % failure rate, subaru about 15-20%

 

In your case I am not convinced it is a HG. Lets start off simply with a new Radiator cap. If it was a HG you would have overheated and not run hot. Also your T-stat is old and can probably use a replacement.

The hg's are less than a year old as is the radiator cap and t-stat. One thing that came to mind is the heater hose is not factory and had to make due with what I could get, might be a pinch point there that prevents the hot water to flow until the pressure is up.

 

Will check the levels in a few.

Is the T-stat from subaru? Where are the HG's from as they should have been from subaru too.

 

Check your alt output also above 1800 rpm with everything on.

t-stat is factory

 

Not sure on the hg's, those were purchased before I bought it.

 

Levels are good.

 

Heat went to 3/4 and stayed there while I was idling at a construction stop point this morning. Went back to half once rolling again.

I dont think this is a HG issue (yet). Flush the cooling system. Check for any collapsed hoses. What brand is the T-stat. Any sign of fluid loss.

Why 97/98 legacy?

 

This is the year that subaru moved from composite to MLS head gaskets mid 97 for 2.2 sohc, and for 2.5 DOHC in forester and GT.

 

There have been revisions of the head gaskets that supercede old part numbers, so if you purchase a new gasket for those engines, they are the current updated design with more layers or refined design than what originally came on those engines for those years.

This is the year that subaru moved from composite to MLS head gaskets mid 97 for 2.2 sohc, and for 2.5 DOHC in forester and GT.

 

There have been revisions of the head gaskets that supercede old part numbers, so if you purchase a new gasket for those engines, they are the current updated design with more layers or refined design than what originally came on those engines for those years.

 

 

The only sure bet on that is if purchased from Subaru. Iy is a bit of a gamble from anyone else.

Any leaks from the water pump and how old is the water pump?

This one actually sounds fairly easy to diagnose. No heat and high temps at idle. Air in the system right? Do we all agree with that? Now, how did it get there, thats the question. A small leak? Maybe a bad clamp or hose? Did you recently open up system to do some work? These things can be a *************** to burp. Hopefully its not headgaskets but it always seems to be.