HELP??? Any suggestions

[2001 Legacy GT]

Problem started after replacing lower rad hose (3 weeks ago). Drove over 100 miles and car overheated. Pulled out thermostat checked with boiling water, put it back in. Overheated 120 miles later but would cool back down. Here is what I have done since then.

 

1. Replaced thermostat with new one from NAPA.

2. Put in new spark plugs.

3. Put in BG 44 fuel injector cleaner.

4. Replaced radiator cap.

5. Did a chemical combustion leak test (negative)

6. Did a pressure test on cooling system (negative)

7. Replaced thermostat again.

 

No oil in water

No water in oil.

No external leaks found.

Only white exhaust when first starting, normal exhaust when warm.

No oders.

Burp tank functioning properly.

 

No pattern for overheating. Every 5-6 days (maybe)

Did I just get a bad thermostat, and it is now fixed???

[bobo69]

airlock somewhere??

[deneb]

Bad water pump, or if it's belt driven, a slipping fan belt? A belt can slip without making that horrible screeching sound usually associated with a slipping belt. Dunno if the 2001 Legacy has a belt driven water pump or not.

 

Have you verified no leaks while the engine is running? Has the new thermostat solved the problem?

[schwinn]

I agree - air locked up somewhere, which is a common problem on some cars - my old MX6 had this issue. The coolant flush procedure is pretty important in these cases. Not sure if the LGT is one of these types... but I thought it might have been mentioned somewhere on these forums?

 

Secondly, though unlikely, a bad water pump? Or something not allowing for proper water flow? A "broken" water pump could do this, in theory... but I would imagine a clog in the system would be more likely than this. Bottom line is that nothing you have done has tested the flow of the system.

 

Might want to check the pressure (via a gauge) of the system, too... if it's not holding pressure, then it won't be able to keep the water from boiling.

[2001 Legacy GT]

I am with the air lock. Drove today and it overheated within 3 miles. Lost heat in heater, but returned shortly after. Bled system for 1 hour with front of car elevated on snow bank. Test drive for 30 miles. No problems and heater worked very well. thank god since it is only 13 degrees outside and that does not include the wind.

[2001 Legacy GT]

And just so you don't think I am an idiot; My dad taught automotive for 30 years. My parents had 5 girls. One of us listened!!! He is almost as confused as I am.

[mickeyd2005]

I don't think you bled the engine properly after draining the coolant. The Subaru boxer engine is notorious for being difficult to fill.

 

For example, in late 2004, Subaru issued a TSB warning their mechanics to follow the coolant drain and fill procedure as stated in the service manual. They then REVISED the service manual. The 2005 service manual floating around the internet was actually printed prior to this TSB.

 

The 2007 service manual has the new fill procedure. It's basically a series of high speed revs and stops all done within a certain amount of time and the engine is not allowed to heat up.

 

A better method is to use a vacuum to evacuate all the air from the system and then fill the engine with coolant. Since there is no air... then there is no air pocket.

 

BTW, I had a hard time bleeding the air out of my '98 Outback.

[2001 Legacy GT]

Hopefully we have fixed the problem. Got it back up in the air this morning. No air bubbles until it was up to normal temp and even then only an occasional bullbe. It will get a real test today. Have no choice but to drive 140 miles later today.

 

Thanks for all of your help. I will let you know if the problem is finally fixed.