ER27 cooling issue

[Numbchux]

I'm having some seemingly conflicting symptoms. I'd like to put it down, and see if anyone has any suggestions.

 

 

Car: 1989 4EAT AWD XT6.

 

117,5xx miles, so yea, it's been sitting more than driving. Specifically the last 6 years or so, outside with a drained and open (missing upper hose) cooling system. Rust and/or corrosion probably a major portion of the issue. Virtually stock cooling system (with the exception of one radiator cap....I'll mention later).

 

Cooling/heating system worked perfect when parked.

 

 

When I first started driving it again this fall, I let it idle several times up to operating temperature to make sure the system didn't leak when pressurized, and the fans worked correctly (check and check).

 

Seemed to be very slow to warm up. New Subaru thermostat and gasket were installed, no change.

 

 

The last week or 2 (it's been very cold, several mornings more than 10 below, may or may not be related), I've noticed occasionally that at a stop, the temperature creeps up. about 2/3 on the gauge, maybe a bit more. Not quite enough to be alarmed about, but definitely more than it should.

 

 

As soon as I start driving again, it cools down, immediately. All the while, putting out pretty luke warm heat into the cabin. This all sounds to me like it's not getting very good circulation, clogged radiator and/or heater core and/or water pump etc.

 

BUT, once I start driving, it cools down below "normal". This doesn't seem to make sense to me. I'm assuming the thermostat is closing as it should, and blocking off flow to the radiator, and it's certainly not dissipating a massive amount of heat through the heater core....how could it be overcooling?

 

This doesn't usually happen for long, this morning, I tried revving the rpms to about 2500 while at a stop to try to isolate airflow vs. coolant flow, and it didn't seem to make any difference. This seems to me like it would point more towards a clogged radiator....

 

 

 

Thoughts?

 

I think once it warms up, I'll flush the engine, radiator, and heater core separately. Any recommendations for a flush/cleanser product? Maybe throw the thermostat in a pot and make sure it actually stays closed as long as it should.

 

I had a small coolant leak that I thought was the small bypass hose near the radiator cap over the thermostat housing. I replaced that cap with a higher pressure one (EJ 16psi, instead of the stock XT6 13psi). My thought process was that it might prevent the cap from releasing, and therefore reduce the pressure in that bypass hose. It did stop my leak, but I suspect it may have been the cap itself leaking. I'm now concerned that the fact that this cap isn't opening might be reducing flow to the thermostat housing, and preventing it from working as it should....somehow. I'm considering either buying one (or maybe two) new XT6 caps (my cost on OE or aftermarket is about the same, but OE is way less available), or one new EJ cap (considerably cheaper) to match the other. These would have the same effect of equalizing the pressure and restoring flow through the thermostat housing. On one hand, higher pressure would increase the boiling point, which shouldn't be an issue. It puts a little extra strain on the hoses and seals, but I don't think 3 psi is that big a deal. Am I missing something?

 

 

I have no idea the condition or history of the timing belts/water pump. But being as this is just a daily/RallyX beater, and non-interference. I'd really rather not delve into that realm if I don't have to.

[crazyhorse001]

My fwd 6 does this sometimes. Not hot enough to worry, but just plain odd.

Check the lighter fuse, it feeds the a/c fan relay. Not sure why it helped mine, but it did. Both fans worked, but the a/c wouldnt. Replaced that fuse, and it was cool, and happy again with frosty a/c. This 6 has never had what you'd call hot heat tho

[idosubaru]

maybe whatever caused the radiator to partially clogged also did the same with the heater core?

 

i think thermostat failure is far more rare than comments suggest but it probably needs checked?

 

i've never really done a flush so i'm not sure. ;

 

i ran a garden hose through a forester radiator and a known good radiator in my garage.  the forester radiator barely trickled water through it while the other one flowed fine.  not that this is a fun test when it's frigid out - i don't even want to change oil right now much less run water through a radiator.  LOL

[maozebong]

as far as flushing solvents, ive had luck with CLR for removing mineral/rust buildup. ive also had some success with BG products too. i add them in the system and drive it for a week or two, then flush. there is no substitute for a large volume of water though. after using cleaners, debris has to be carried away. 

 

i also had similar symptoms when i had a minor intake gasket leak on my ea82. burping the system with a coolant funnel made it go away for a week or two at a time. i replaced the gasket and still had problems til i found the leak at the throttle body. then the problem was gone. 

[Caboobaroo]

I had a similar issue with mine years ago. Turned out to be a partially plugged radiator. Ended up breaking the upper inlet off on the freeway on my way to work. Swapped in another one and my issues went away.