I'm learning altogether too much about Subarus since my son bought one and it's been one problem after another. He just arrived home after having driven 10 miles with the temp gauge pegged! How prone are the 2.5 liter motors to warping the heads when overheated? I'll start trouble shooting this piece of junk in the morning. Is there anything "special" or routine in the way these motors fail or should I just do the usual checks for thermostat,oil and antifreeze mixing, etc.?
DeadSkunk wrote: How prone are the 2.5 liter motors to warping the heads when overheated?
Sadly.....very.
Headgaskets - what year?
If it's a DOHC 2.5 look for a milkshake where the oil should be (coolant in oil or vice versa), if it's a SOHC 2.5 it should be an external leak.
These little all aluminum watch winders are not good friends with being over heated. They do like to warp. And like Jed said the phase 1 na's fail internal while phase 2 na's fail external. Of course it could be a busted hose and if it was still running, who knows...it might be okay.
Good Luck
@ OP Year make and Model of the car?
If the Oil looks ok figuar out where the water went (hose rad etc) Fix that and I would fill it up with water and see what happens.
If it leaked internally or you find a HG leak then time for head gaskets.
A full coolant overflow bottle is a sure sign of an internal head gasket leak on these.
If anyone tried to fix the leak with some parts store HG fix in a bottle then the radiator could be clogged as well. (Ask me how I know)
Sorry about not putting more info in my original post , Guys. I was more than a little ticked off at 10:00 PM when he brought it home. It's a 1999 Legacy Outback with the DOHC 2.5, lucky me.
I dislike the dual cam motors.
They leak internally, which this one probably did. You're almost certainly looking at a head gasket replacement. Heads are probably warped a bit so those should go off to the machine shop. Make sure they pressure test them to check for cracks while they're at it. These heads have adustable puck type lifters that are $6/ea. at the stealership. I once spent $100 on lifter shims for those motors. Never again! I'd bail on this one.
Ok. Initial inspection shows it was a gallon short of coolant. There was some evidence of coolant on the driveway, but certainly not a gallon sized puddle. Checked the dipstick and it's black/dark brown and at a normal fill level, which I've taken to mean there's no coolant in the oil. Started it and let it idle. After 10 minutes or so it got up to 40% on the temp gauge. A few minutes later it started both cooling fans and the upper radiator hose was getting hot, as expected. I left it run and eventually it got up close to the hot mark, so i shut it down. Added some more coolant to top it up and waited 15 minutes.The second time I started it up and let it idle it stayed at normal temp for quite a while and didn't go back up to the hot mark. The only thing that seems a little odd to me is the lower rad hose isn't very warm at all and I would expect it to get warm, but not as hot as the upper. I'm assuming the thermostat is buried under the intake manifold where the end of the upper rad hose goes, so that will be a PITA to change. Don't understand why the lower hose is barely warm while the upper is untouchable, unless the rad is plugged and not flowing enough coolant. Any other ideas, Gang ?
Thanks
Warren
Oops. Just found out that the thermostat is on the pump outlet, lower radiator hose. That would seem to show it didn't open if that lower hose isn't getting any where near as hot as the upper hose.
It sounds like you might have an air pocket in the cooling system. It is a giant PITA to bleed the cooling system on a Subaru, usually takes multiple attempts and lots of cursing. Add some redline water wetter, jack up the front or park it on an incline and try burping any air out. Unfortunately if your son already drove around the with the temp gauge pegged, I'd echo the sentiment that there is a 1% chance you get lucky and the heads aren't warped. As far as the thermostat, I know on the later SOHCs the t-stat housing is pretty easily accessible behind the radiator. Assuming the DOHCs are the same it might not be a bad idea to throw a new one in. I would suggest sucking it up and buying one from the dealer, most of the aftermarket ones are crap.
Step 1 - Ask son to sit in the driver's seat, point to and name all gauges out loud.
Step 2 - When son reaches "Temp Gauge" ask him to point and repeat multiple times.
Step 3 - Open hood, ask son to name large object located there in.
Step 4 - Wish son luck in fixing it, offer to loan tools for a very favorable rate.
(my apologies to Bill Cosby and the "no gas in the car" bit)
Sounds like your son is about to learn how to R&R a Subie engine. Should be a great character builder.
In reply to Stargazer:
I hadn't thought about an air pocket, but if I had to put 4 liters in to fill a 6 liter system, there was bound to be a lot of vapor in there. That may explain why the second time it didn't go to "Hot". An air pocket may have moved, or something. I'll try the new thermostat if for no other reason than it's the cheapest thing to try. If he didn't warp the heads I think I'll go buy a lottery ticket. My lucky day.
In reply to slefain:
I did all of that this morning in my van to be sure he doesn't blow it up, too. The only thing on your list I won't let him do is touch any car, his or mine, with tools. It'll just result in more work for me. He'll never be a gearhead, just needs a dependable appliance vehicle. Unfortunately, I'm the one who picked this one out for him so I feel a little responsible .
Open the radiator cap and then squeeze the bottom hose. You should be able to push coolant up to the cap freely. If the lower hose is under pressure and you can't squeeze the coolant through the radiator, you have a blockage in there and it needs to be replaced.
Fornetti, I'll try that once I put the new thermostat and coolant back.I took the old thermostat out and ordered a new one. I boiled the old one and it was fully open before the water actually boiled, so I'm not very optimistic that the new thermostat will change anything in the morning. I think I'll see if I can flush the rad with a garden hose. Unless the rad is blocked it's looking like the head gasket (s) is blown, although I'm still not sure why the lower hose wasn't hot to the touch while the upper was. To me this indicates that there wasn't any flow into the rad through the lower hose. The playing will continue tomorrow.
Waterpump or clogged rad?
I replaced the water pump when I did the timing belt about 3 months ago. I would hope it hasn't failed in ninety days. What I may do is take the valve out of the old thermostat and just install the outer portion. That way I'll be positive it's not closed and we'll see if if the lower hose gets hot.
Flushed the rad and water flowed through it rather readily. Boiled the old thermostat and a new one to see if they both functioned normally. They did, so I put the new one in. Lower hose got hot after several minutes of idling, as it should. Went for a drive and temp gauge was less than halfway for 5 or 6 miles, then it went up to the hot mark pretty quickly and I nursed it home before it boiled over. I had removed all the antifreeze to flush the rad and replaced it with straight water for the drive. I got 1.5 gallons of water into it which is the system capacity. To me , everything external to the engine is behaving normally.The only thing that's throwing me off is there's no coolant in the oil, or oil in the coolant so if there's a head gasket failure where is it? Between two cylinders? What else would cause the thing to overheat? Am I missing anything? I am getting to close to walking away from this POS and just take the $200 I can get from the scrap yard.
Wish there were a home test for hydrocarbons in the coolant...
Couldn't a head gasket fail between the combustion chamber and a coolant passage?
Compression test? Leak down test? Any steam coming from the exhaust? A BHG between the cylinder and a coolant passage will behave as you have described. Had it happen on a 22R once.
Pull the plugs, if one or more looks new (violently white insulator) you have a blowout to the cooling system.
More things to check. Hess, no steam from the exhaust. I've got a compression tester and I knew the plug stunt from years ago. Just getting old and forgetful, I guess. Thanks ,Guys.
What are you doing when the car overheats? Are you idling? Are the cooling fans still coming on and working correctly? Is the fan clutch good (or electric fan)?
I have to wonder if you're dealing with an air pocket, as others have suggested.
You'll need to log in to post.
