Need advice diagnosing overheating on 1997 2.5 Legacy Outback

[Lex1997]

Hey Gents,

 

My very old neighbor has a 97 2.5 automatic. 140k+ miles, leaking oil from every orifice, strange noises coming from rear diff during turns.....its on its deathbed. He uses it to go to pharmacy and supermarket.

 

Anyway its been overheating for the last year. He is very sickly and absent minded so he cannot give me a straight answer about what happens when it overheats. Its never had anything but minimal maintenance so we changed the thermostat and radiator cap (Subaru OEM) for first time.

 

After we changed it we ran it with the cap off to burp the air out (heat on high in cabin). After 15 minutes the cooling fans came on and the temp gage was at normal temps then went to 3/4 temps but the coolant in the radiator was barely luke warm and the car had no cabin heat.

 

I started doing research and realized these supposedly bulletproof Subarus are notorious for blowing head gaskets and this leads to air being introduced into cooling system. OOOOPS. So much for that reputation...

 

Coolant has no oil in it and oil has no coolant in it.

 

How do I know if its the water pump (original) versus a blown head? I want to do a carbon monoxide in coolant test but if the radiator isnt burping will I even get any combustion gas in it to test for?

Edited February 7, 2021 by Lex1997

[doublechaz]

The car has been abused for 25 years and now it's broke? What a crap manufacturer! They sure don't deserve a good reputation.

[Enlight]

Good on you for helping an elderly neighbor. Everything you described tells me it isn't a head gasket issue, though it's still possible. I would follow the burping procedure in this thread (link) and see if there's any improvement.

[Osei]

Being new to Subarus, you don't know that the T stat being on the bottom of the block does not not allow sufficient coolant into the system by only filling the radiator.

It has to go through a lot to burp properly this way.

The easiest and best way is to fill the block from the top radiator hose and then the radiator.

O.

[Lex1997]

Thanks guys. Much appreciated it. I will check the link out.

 

I have a leakdown test kit and a cooling system pressurizer. But I assumed the thermostat was the obvious culprit. Too add to this senior citizen's pain, he is living on a small fixed income. Sad situation.

 

This Subie specialist has some insights and in another video mentions the reasons for overheating and doesn't even bring up the water pump (gulp!), which was my my initial diagnosis after we changed the thermostat to no avail. Apparently the water pump isn't the typical culprit.

 

[Lex1997]

Being new to Subarus, you don't know that the T stat being on the bottom of the block does not not allow sufficient coolant into the system by only filling the radiator.

It has to go through a lot to burp properly this way.

The easiest and best way is to fill the block from the top radiator hose and then the radiator.

O.

 

ok I will try this as well.

 

Note that it did take all the coolant we drained out of it. Of course its lost coolant so many times in the past and he is so compromised mentally that he cannot tell me for sure what's gone on. It may be low on coolant for all I know.

[Lex1997]

Good on you for helping an elderly neighbor. Everything you described tells me it isn't a head gasket issue, though it's still possible. I would follow the burping procedure in this thread (link) and see if there's any improvement.

 

I checked ALLDATA and didn't see anything about a vent plug. It says:

 

1. With engine cool, open radiator drain plug and drain coolant into a suitable container.

2. Remove radiator pressure cap. Never open cap with engine hot.

3. Remove and drain coolant reservoir.

4. If equipped, remove drain plug(s) from engine. When coolant is completely drained, install the plug(s).

5. Close radiator drain plug.

6. Install coolant reservoir.

7. Slowly add coolant to radiator until fluid level reaches filler neck.

8. Slowly add coolant to reservoir until fluid level reaches Full mark.

9. Install radiator and reservoir caps.

10. Start and run engine at 2000-3000 RPM. When operating temperature is achieved, stop the engine.

11. With engine cool, remove radiator and reservoir caps. Never open cap with engine hot.

12. Add coolant as needed until fluid level is as specified in steps 7 and 8.

13. Install radiator and reservoir caps