97 outback getting hot

[gzbmw]

Hi All,

I'm new to Subaru's. Just bought this one with 246,000 kms on clock, 2.5l, manual and would appreciate some advice/confirmation.

I flushed the radiator without the thermostat, with a rad cleaner. Flushed it good with heaps of fresh water in every orifice I could find (heater on). It was not overheating before and the temperature gauge was just under half. I did this for preventative maintanence.

I may be paranoid, but after re-installing the thermostat, and running it on idle, it takes (for me) too long for the coolant to flow through the thermostat. Bottom rad hose is cool after 30 mins of running, then starts to warm up. I checked the thermostat in boling water and it opens up as it should before the water boils.

The block seems to be very hot. Hotter than I would like to to be.
The temperature guage reads a needle thickness under half.
Our ambient temp is 12 deg C or 53 deg F.
Just to be sure, the spring end should point towards the block, yes?

Am I paranoid? or is all as it should be?

cheers,

George

[grossgary]

be careful, you have one of Subaru's worst motors when it comes to overheating, head gasket issues, etc so you don't want to help it along in that regard:

1. they have massive headgasket issues - read all week along on the interweb
2. that motor is also notorious for getting air pockets in it and they need burped if any coolant is drained to make sure all the air bubbles are out. some radiators have a plastic bleeder screw on the top passengers side of the radiator, open that while filling to let bubbles out.

are you positive this was only "preventative" maintenance?

when it reaches operating temperature - does it immediately have hot air on demand? turn the vents on high and all the way hot and run it for a while - do you always have hot air or does it come out hot initially then the temp decreases?

the temp gauge is what you should be able to look at it - if it says it's overheating then something is wrong. if it says the motor is fine then it should be fine.

yes - spring towards block.

your radiator may be clogged. radiatorbarn.com has cheap new radiators shipped to your door but maybe you're international?

[plain OM]

It was not overheating before and the temperature gauge was just under half. . . . . after re-installing the thermostat, and running it on idle, it takes (for me) too long for the coolant to flow through the thermostat. Bottom rad hose is cool after 30 mins of running, then starts to warm up. . . . . . Our ambient temp is 12 deg C or 53 deg F.

These all-aluminum engines are quite capable of dissipating heat on their own, especially when the engine is just idling from a cold start. (All the more so, if the hood is up, and the ambient temp is low.) And if the engine is running efficiently, it will not generate as much heat when idling as when driving.

Checking at the lower rad hose isn't going to tell you much. At idle, the coolant flow rate is slower, and as coolant goes through the radiator, it is cooled -- that's what it's all about (even with the fans off). Consequently, the lower rad hose could very well remain relatively cool (based on touch) even though the thermostat is, in fact, only slightly open and regulating the engine temperature. In contrast, a hot lower hose could indicate that the radiator isn't removing as much heat as it might.

If the engine doesn't appear to be overheating according to the temperature gauge, and the radiator fans aren't coming on, I'd tend to think that the cooling system is working fine after your flush. If you're doubtful, and suspect overheating despite the gauge, use an infra-red thermometer to check the temperature at the crossover pipe. (This is the pipe that goes between the two heads, the right side of which leads to the upper radiator hose.)

grossgary's idea to check the cabin heater output is also good. In fact, with the heater fan on, the heater can draw out a lot of heat, so again, with the heater fan turned on and the engine only idling, the thermostat might not be open, or only open slightly -- there's enough coolant circulation through the block and the heater core to keep the temperature in check.

[gzbmw]

thanks for the replies.

Question. Should the head get so hot that you can't leave your hand on it after 30 mins of running?

My next step is to get a IR thermometer and check temps around the block and heads.

Also, there are no bubbles in the coolant at the rad cap opening.

Cheers.

[JavaTee]

Originally Posted by gzbmw

thanks for the replies.

Question. Should the head get so hot that you can't leave your hand on it after 30 mins of running?

My next step is to get a IR thermometer and check temps around the block and heads.

Also, there are no bubbles in the coolant at the rad cap opening.

Cheers.

Reread the first reply to your post.

On your radiator, passenger side there should be a small phillips head plastic screw to remove a 'burping plug' from the radiator.
Pull your Outback up on some low ramps/elevate the front of the car up a little to help in relieving the block with the air that's in it. Our Subie boxer engines are not your typical inline 4/6 cylinder or V6/8 for that matter, and require a different coolant filling method then most of us are used too.

Good luck,
T.J.

[grossgary]

if you place your hand on the head then your hand is a very small distance away from violent explosions and combustion....yes it's going to get very hot.

[gzbmw]

Yes, I am international, Melbourne, Australia.

An update. This afternoon, I drained the coolant, installed a new OEM thermostat and gasket. I checked that it was working properly first with a thermometer in hot water. I flushed the rad fwd and reverse flow only, not the block. Flow was strong so it appears not to be blocked at all. Refilled it, ran it for 10 kms or 6 miles. All the time, the temp gauge was just under half and did not fluctuate.

When I came back, I cracked open the vent screw (but not all the way out) and some coolant and bubbles appeared to come out intermittenly.

Now, after the run and while idleing, the RHS electric fan came on for 15 seconds or so then went off for 5 mins. It did this a few times.

With an IR thermometer, the top hose was about 80 deg and the bottom thermostat cover was about the same. Gauge did not budge from its under half reading.

I think all is OK with my suby.

A question, if the headgaskets were buggered and allowing exhaust gases to bleed into the coolant, what would I be seeing from the bleeder screw or the rad cap opening? size of bubbles and frequency?

Just how long does it take to bleed (burp) the air out of the system?

I'll be monitoring this over the week by releasing the vent screw and seeing what comes out.

Thanks for your help

regards,

George

[maddog39]

If you have HG problems that have progressed pretty far, you should be able to open the coolant overflow reservoir after running the engine for a while, and see the coolant bubbling up. You might also see exhaust residue inside the tank.