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Hello All,

 

I have an issue with a 2001 Subaru Outback that I have never come across before. In the middle of moving from Albuquerque to Hawaii my Outbacks air conditioning dyed at the californai state boarder in route to Los Angeles (about 100 deg. at time). For ~ 2 months prior to this trip the check engine light would come on, but would turn off usually after I removed the gas cap then put gas cap back on... figure old cap not keeping pressure. Okay, fast forward from california boarder to three weeks later after picking up outback it now has check engine light on continuously. Week after that (~ 300 miles on car since air conditioning went out), I noticed when car was stopped at a stop light or in a parking lot still running, the temperature gage would begin to rise toward the red zone (over heating)... when I could drive the temp gage heads back toward the normal temp operating range...

 

At this point you might be thinking, relay?, fan?, plugged radiator?, makes sense. The car is NOT over heating, infact the mechanic actually took the radiator cap off while the cars temp gage was "red lining", and of course we could hear/see that the fan is kicking on. Now stuck in traffic, you can put the car in neutral and rev the engine to "kick on" the coolant pump, and the temp gage would come back down to normal temp range, you can open the vents, crank up the hot air (do not have working ac at this time) and buy some time before the temp gage crawls up to red line....

 

My problem here is... what on the planet can cause a car to read like it's overheating without it overheating? Yet, causes the air conditioner to stop working, since the check engine light (read cooling problem) was cleared the car has continued to repeat the above issue without triggering the check engine light... With the age and milage I would just let this go as a unique quirck, however Hawaii is hot, I have a 2.5 year old, and AC would be nice, but why spend money on recharging etc... if this problem might just kill it again?

 

The mechanic thinks it's electrical, but does not do electrical. Other than the temp gage reading like a perfect fan/relay/plugged poblem and the AC dying nothing else is wrong with this car.

 

This is a tough one, any ideas my fellow subinites might have will be greatly appreciated.... Thank you!

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Several ideas here.

Coolant level low,

Thermostat is sticking

Water pump impeller is worn,

Fans are not working at both speeds,

 

Fans are easy to test. Poke your head under the dash and find the two green plugs. Plug them together and turn the key to On.

 

This will cycle the fans on low-high and off in about 2 second intervals. Make sure both fans work at both speeds. Turn key off and unplug the green connectors. Once fan operation is verified, plan on replacing the thermostat.

You have to get a GOOD thermostat for these. Subaru OE or an equivalent design such as Gates or Stant Exac-stat. Big difference between one of those and a cheapo.

 

Take the car to an auto parts store and have the check engine light scanned. Even if it's not on, there are still codes stored that can help.

 

AC probably just needs a recharge.

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Fairtax,

 

Thanks for the ideas! So the coolant is not low, and I would assume if the thermostat was sticking I would not have such a smooth increase/decrease response in the temp gage? With those ruled out I went ahead and tried the fan check (big thanks), but alas... although the fans were not quite in sync with eachother (no reason they should be, that I know of) they both cycled beautiful from low to high to off. If I can ask, why so certain on thermostat with verified fan operation? water pump impeller sounds intriguing, however the car is not actually overheating... even if left running so that the temp gage rises to the red for a while.... seems like impeller would be an overheating culpurit. If this fourm would allow the MB's I could have posted a video demonstrating the smooth temp gage pointing at an overheat in non motion situations, however not the true case...

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You havent mentioned if the radiator cap has ever been replaced. They do fail with age.

 

How do you know the car isnt over heating?

 

When it runs hot do you have heat?

 

What worries me, when was the last time the timing belt was serviced.

 

AC is probably just a bad oring in the system.

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Your temperature gauge is before the thermostat in the water system (in through the top out through the bottom).  Your thermostat is before coolant goes to the radiator (again, in through the top and out through the bottom).

 

If your thermostat is sticking it will let the inside of the engine heat up without getting fresh water into it to cool it down.  Fans can kick on all they want, but if the water isn't circulating they aren't doing any good.

 

And when you put your foot down this can be occurring:

 

Timing belt turns the water pump faster, i.e. pushing more water.

 

the additional water pressure can be forcing the thermostat to open.

Edited by lstevens76
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is this an H6 ez30 or the ej25?

 

on the 01+ H6,

the AC will cut out any time the car (gauge) overheats.

it is designed to reduce the load on the overheating engine,

 

 

i cannot figure out the rad cap removal when the gauge is red line.

this is beyond me.

 

rad caps fail way more often than t-stats, factory t-stats at least.

 

i would address the over heating first.

 

ej25 or ez30???????????????

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i

 

i cannot figure out the rad cap removal when the gauge is red line.

this is beyond me.

 

I figured on this one either:

 

1.)  He had the rad cap off and let it warm fully up to the point of the temperature gauge reporting red line to see what was happening.

 

2.)  He slowly pulled the cap, meaning he let a lot of coolant flow into the overflow before he could pull it.

 

3.)  If he didn't have to do either of the above he should have known at that point it was either a faulty temp sender, thermostat, or water pump.  With a faulty thermostat being the most likely culprit.

 

And finally I would be more worried about a possible coolant leak the more I think about this.  It almost sounds as if there is air in the system and the reason he was able to pull the cap off while it was running is because there wasn't enough pressure on the system.

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Thanks for the ideas! So the coolant is not low, and I would assume if the thermostat was sticking I would not have such a smooth increase/decrease response in the temp gage?

That kind of depends. The thermostat could be closing more than it should and blocking coolant flow, and the guage will reflect that as coolant flows out of the engine.

 

The thermostat on these cars is on the inlet side of the water pump, meanings its on the cold side, where cool coolant from the radiator has to flow across the thermostat before it goes into the engine. This is where the importance of using a real subaru OE design thermostat comes in. The proper design doesn't react as quickly to small changes in temperature. A 10° drop in temp will make a cheapo aftermarket thermostat completely close, and it won't open again until the engine gets 20-30° hotter, at which point it may go wide open and allow too much coolant flow, which just causes the cycle to repeat.

The Subaru thermostat will close slightly, but not completely, which means it will regulate temperature more evenly, rather than giving the roller coaster effect.

 

The thermostat is a moving part, so even if you have a Subaru thermostat in the car, if its old it could be worn out or is staying in a closed or partially closed position for longer than it should.

 

 

 

Thermostat opening temp for these is 170°. This is the point when the thermostat just starts to open. Normal operating temp is 190-195°. The thermostat should be wide open at 195°.

Your temperature guage will read right around the middle for any temperature between 170° and about 210°. The guage is designed NOT to fluctuate greatly when in that center range, even though the coolant temp may change 10-15 higher or lower within that range.

The difference on the guage between the middle and the very top is from about 210° to about 230°.

 

The radiator fans will turn on at 204°. They will run until the coolant temp drops to 194°.

At 204° the guage will still show dead center.

So if the guage is showing hot, use an infrared temperature gun to verify the coolant temp coming out of the block just before the upper radiator hose. If its above 204, and the fans are Not running there could be a problem with the ECT sensor that the computer uses. If it's below 204° but the guage still shows hot, the ECT sensor for the guage is probably faulty. I believe on the 01 the temp sensors are built into the same unit.

 

If the fans are running, guage shows hot, and temp on the IR gun shows higher than 204°, it's either the thermostat isn't opening properly, or the water pump isn't moving enough coolant.

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Ok, I had the direction of flow backwards for some reason.  I also agree with Fairtax as well in everything he said.

 

The same situation though regarding flow and pressure.  When the water pump moves faster it creates more pressure and more flow which can change a lot of things.

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Thank you everyone!

 

Addressing a few things... the timing belt is about 14 months old.  We are dealing with an ej24. The point about getting the cap off while "red lining" and not seeming overly hot, does give concern about air/lack of pressure... the rad cap has never been replaced, but I also do not have any visable leaking along coolant flow path...

 

you guys have been great! I love this car and intend to keep it for quite some time to come so I will start with thermostat (OEM, of course), if that does not work I will report back but likely move to ECT sensor next, if temp. is tracking the way Fairtax mentioned.

 

Your temperature gauge is before the thermostat in the water system (in through the top out through the bottom).  Your thermostat is before coolant goes to the radiator (again, in through the top and out through the bottom).

 

If your thermostat is sticking it will let the inside of the engine heat up without getting fresh water into it to cool it down.  Fans can kick on all they want, but if the water isn't circulating they aren't doing any good.

 

And when you put your foot down this can be occurring:

 

Timing belt turns the water pump faster, i.e. pushing more water.

 

the additional water pressure can be forcing the thermostat to open.

this part scares me, as I could be doing some damage unknown during troubleshooting.

 

I'll report back

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I would replace the cap because it is old, they are cheap enough and do age.

 

When the timing belt was replaced, what else was replaced along with it?

 

Thermostat is a good place to start too, get one from subaru, not aftermarket.

 

Is the radiator free of debree and intact? Sometimes cooling fins corrode with age, and the radiator can clog up. 

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Nipper,

 

So, I have owned the car (second owner) for over nine years... last year was the first major work that had to be done... oil leaking into spark plugs. A known issue that a long time subi mechanic knew how to fix permanently (and promised another 100k, currently only 180k on it). Looking through that work to give you the details as to what other work was done I found out that the mechanic (last year) did replace the thermostate (OE)!!!! Crap!

 

In addition to the thermostat, also machined the heads, replaced the cylinder head gaskets, 2 idler pulleys, timing belt, spark plugs, and spark plug wires, and knock sensor. About a week before that (and not knowing the sinister truth at time), replaced ac high pressure line, and replaced ac reciever drier... yeah, last year was about 2500USD in work.

 

What is the chance of the thermostat OE failing in a year?...

 

Radiator/fins look good and in tact

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What head gaskets did he use?  That was a lot of work currently done and most of that had nothing to do with oil leaking into the spark plugs, nor can you realistically permanently fix that problem.  The oil into the spark plug wells is due to the o-rings in the valve cover gasket failing and they will do it again with age (just a fact of gaskets).  Although 100k+ is realistic for the replacements to hold.

 

It does seem odd that he replaced the idler pulleys and not the water pump nor the tensioner.  I would question the water pump in this situation.  If that water pump is at 200k+ miles it could easily be the problem.

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What he said about the water pump.

 

Can you do this? After using the car and putting it to bed, place a peice or several clean peices of cardboard under the engine over night. Look for drips.

 

It is extremely unusual to do all that work and not replace the water pump.

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It sounds like it's overheating - but you say it's not?  Why do you suspect the gauge to be wrong?

 

check simple stuff first - proper coolant level, burping, tstat, cap, etc.

 

1. radiator clogged

2.  headgaskets

 

Are there any bubbles in the radiator or overflow tank while idling, running, driving, overheating?

 

i've never seen a failed Subaru EJ water pump - except one that's leaking through the weep hole.

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When engine temp gets high, the computer will turn off the Ac automatically until temp is back to normal.  Sounds like a stuck thermostat or restriction in coolant flow since speeding  up engine driven coolent pump helps with circulation (speeding up engine would not likely help if the problem were electrical). I would try a coolant flush and new thermostat.  (Just an  inexpensive and simple idea that might help.)

 

Note: If you can check the temp of the area around the coolant sensor, see if it is real warm. The sensor could be reading corrcectly and there is a build up of heat in the areas affected by the restriction.  If you keep driving your car with this hot temp cycle each time it will not be long before the head gaskets will be leaking.  This engine does not like overheating or hot spots.

Edited by brew7420
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