Subaru Legacy Forums

Subaru Legacy Forums (http://legacygt.com/forums/index.php)
-   Second Generation Legacy (1994 - 1998) (http://legacygt.com/forums/forumdisplay.php?f=95)
-   -   Overheating, no evident leaks (http://legacygt.com/forums/showthread.php?t=202690)

Mitchael 03-01-2013 08:28 PM

Overheating, no evident leaks
 
1997 Legacy Outback 2.5 Automatic trans ~200K miles.

Every so often it spikes in temp, but a couple mechanics have looked at it, and no one has found a leak. Of course it doesn't overheat when I take it to the shop.

Top radiator hose gets hot, so the thermostat doesn't seem like it's jammed shut.
New radiator cap.
Recently flushed, new fluid.
The weep hole on the water pump isn't leaking, so the pump should be fine.
The heater blows hot (really hot) and this will most of the time keep the temp gauge at or just above normal temp.
The only fluid I seem to be loosing is from the overflow reservoir when the fluid is hot and boiling over.

One forum suggested that the heater core may be bad. I was going to bypass it to see if that fixes it, but I'm concerned it won't, as I still get heat and I haven't noticed much fluid loss or any leaks into the cabin.

My first 97 Legacy Outback 2.5 overheated like this at ~240K and I got rid of it before I solved the problem.

Any suggestions? Is this a frequent thing?

monkeyposeur 03-01-2013 08:53 PM

Either your thermostat is not an OEM t-stat, is bad, or your head gaskets are leaking internally.

Your heater core being bad or clogged is also a possibility, but not a common occurence.

I'd recommend getting a hydrocarbon test done as soon as possible. It will tell you if exhaust gases are getting into your coolant. Is your overflow tank bubbling? Milky? White smoke coming out of your exhaust?

Check your bottom radiator hose for heat, not the top. The bottom hose is directly connected to your t-stat.

travgag 03-02-2013 07:31 AM

+1 might be a random failure of the thermostat sticking or something, but there's definatly things to check

JJay03 03-02-2013 08:17 AM

Hmm a 2.5 over heating I wonder what it could be lol? 90% of the time its the HG's sorry to say. Combustion gasses can get in the coolant and cause it to have a air gap right behind the t-stat with no noticeable signs of leaks.

Scubaru03 03-02-2013 08:27 AM

I would disconnect the top hose from radiator and make sure the block is full and no air pocket. If not that. I would replace the thermostat.

monkeyposeur 03-02-2013 09:02 AM

^Good call about possible air trapped in the system. I spaced that. Personally I would purge or burp the system before disconnecting the radiator hoses.

snederhiser 03-02-2013 09:23 AM

Hello;
Are your cooling fans working properly? Head gasket issues usually show contamination of the overflow bottle, brown coolant. The oil can be contaminated, getting brown with a milky white foam collecting on the filler cap. Any white smoke coming out of the tailpipe? When was the last time the cooling system had some cleaner run thru and flushed? How about a new oem thermostat? If your heater is blowing hot air I figure that the system is working with no trapped air. Steven.

spooln30 03-03-2013 01:49 AM

If your heater core was bad you would have coolant inside your car on the carpets and you would have a sweet smell along with all of the windows would have a film of coolant on them. Probably the headgaskets GL.

pleaidestar 03-03-2013 09:41 AM

+1 monkeyposeur, if it gets hot sitting still and goes to normal operating temp when you drive normally there is air in your system. Burping it is real easy....

Let your car idle for a minute then take that plastic screw out of the passenger side of the radiator and take off the radiator cap, top off the coolant like normal until you see a little bit of the coolant come out of the hole you removed that screw from, then put the screw and cap back in. Test drive it for a few blocks, if your still heating up do the process again.

afixer 03-03-2013 10:17 AM

How old is the water pump. I have actuly had the fins on the pump errode so bad that the pump moved very little water, but enough to circulate just not enought to keep it cool. Also are the fans coming on, could be the sensor. Just one out of the box thoughts to go with the obvious, t stat, head gasket ideas. Relatively new to the sub motors , but have been around a few others for a bit. Good luck with it, hope it works out.

mailman 03-03-2013 11:20 AM

I don't remember if it was the haynes manual or the owner's manual, but somewhere I read that only one fan comes on all the time and that the second fan is an aux. that only comes on with the AC system. In my 96 the AC is broken and I've never had to use it, but I only ever have one fan.

However, I noticed that on the 94, both of the fans run when they kick on (AC off). Which is it?

subadoo_95 03-03-2013 07:19 PM

if eveything checks out fine,than chances are ur headgasket is on its way out.

subadoo_95 03-03-2013 07:24 PM

Quote:

Originally Posted by mailman (Post 4321628)
I don't remember if it was the haynes manual or the owner's manual, but somewhere I read that only one fan comes on all the time and that the second fan is an aux. that only comes on with the AC system. In my 96 the AC is broken and I've never had to use it, but I only ever have one fan.

However, I noticed that on the 94, both of the fans run when they kick on (AC off). Which is it?

i have a 95 and only 1 fan works when needed.during ac the other one kicks in when needed as well.as long as the t-stat is doing its job there is no need for a fan to run all the time.i had this issues before and replaced one of the fittings thats under the throttle body and that fixed the problem..cant remember what its called

Mitchael 03-05-2013 01:58 PM

Thanks all!

I'll try burping it.

There's no smoke or milky film in the fluid. It was flushed a couple months ago, and the fans work just fine, when it heats up and when the AC runs.

mailman 03-05-2013 11:20 PM

Be patient with it... mine has been overheating only when ~2 hours into the mail route. Today when it happened I tried burping it and it kept the temperature down, but then I noticed that my heater only blew hot when accelerating. Eventually it overheated again, and so I burped it again. Same thing. Third time, I removed the plug too soon and coolant spit in my face :lol:

Fourth time, I took my time, opened everything, ran it until it started spitting up, let it cool, did it again, then filled VERY slowly until the bleeder holes and under the cap were full and had no obvious air bubbles coming out. Sealed everything up, and it got me through the rest of the route.

BUT, I'm still not confident that I did it right so tomorrow I have the day off and will do a "dry run" to see if I can get it to overheat again. I never want to see antifreeze again in my life


All times are GMT -6. The time now is 06:26 AM.


LegacyGT.com