Overheating

[Ore Ele]

Hey,

 

Have a quick question (hopefully).

 

I have a 97 subaru outback and when I drive, the cooling system seems to just shutoff and let the engine overheat.

 

In the morning, when I start the car, it starts up fine and warms up fine, and stays at a good temperature. The heater works and the engine temperature levels off where it should. Then, after about 10 - 15 minutes, my heater begins blowing cool air and the temperature skyrockets.

 

I have plenty of coolant and no leaks and I just changed the thermostat since it was due anyway, but there is no change. I also had both the radiator and water pump replaced 6 months ago, though I would not be too surprised if they were not installed properly.

 

Anyone have any ideas, or if there is any other info that could help?

 

Thanks,

[idosubaru]

was overheating the reason the water pump and radiator were replaced?

how many overheats before those and then since those were replaced?

 

when did the overheating start?

 

did you use a Subaru thermostat? (aftermarkets are known to fail and are visually cheap)

if not - was it overheating before you swapped the t-stat (i'm assuming yes but trying to figure out the history here, it may help a lot to know).

 

definitely make sure it's not something simple but sounds like DOHC EJ25 headgasket failure, which is quite common for that engine. blackness in the overflow or coolant pushing into the overflow after you turn the car off are classic symptoms as well.

 

it is odd that it's been doing this "for months" so maybe it's not? that's a long time for something that's shooting up into the red overheating? given the known high failure rate of the headgaskets i'd try to track this down sooner rather than later and keep it from getting into the red. running a headgasket prone 15 year old motor hot is risky.

 

these also get air pockets and can be tricky to burp the air bubbles out of and a rather small amount will lock up the cooling. nose up and fill, nose up and fill, keep checking and opening the cap to let air out.

 

some radiators have a plastic bleeder screw on the passengers side top, just unscrew that and fill until air comes out.

[Ore Ele]

was overheating the reason the water pump and radiator were replaced?

 

The water pump gasket had ruptured and was leaking water, the entire water pump needed to be replaced with it. When that was replaced, the mechanic accidently blew a hole into the radiator (something about not filling it correctly after draining or something, I was a little too stressed at the time anyway).

 

how many overheats before those and then since those were replaced?

 

when did the overheating start?

 

Since the water pump/radiator was replaced (May or June, not sure), it never overheated.

 

This began about 1 1/2 weeks ago. It happened once on my way to a birthday party (didn't really notice anything until we were almost there and the temp was already at H). Let it cool down, and checked the fluids and for leaks. Nothing. Issue didn't come back until Monday (two days ago) and now, it happens every time I drive any distance (still works fine for short distances).

 

did you use a Subaru thermostat? (aftermarkets are known to fail and are visually cheap)

if not - was it overheating before you swapped the t-stat (i'm assuming yes but trying to figure out the history here, it may help a lot to know).

 

Yes, I used a subaru one, and replaced the thermostat just yesterday (after the issue came up), it made no difference at all (still lasting about the same distance before the cooling system stops working).

 

definitely make sure it's not something simple but sounds like DOHC EJ25 headgasket failure, which is quite common for that engine. blackness in the overflow or coolant pushing into the overflow after you turn the car off are classic symptoms as well.

 

So if there is any darkness in the overflow tank, that points to the gasket?

 

it is odd that it's been doing this "for months" so maybe it's not? that's a long time for something that's shooting up into the red overheating? given the known high failure rate of the headgaskets i'd try to track this down sooner rather than later and keep it from getting into the red. running a headgasket prone 15 year old motor hot is risky.

 

these also get air pockets and can be tricky to burp the air bubbles out of and a rather small amount will lock up the cooling. nose up and fill, nose up and fill, keep checking and opening the cap to let air out.

 

some radiators have a plastic bleeder screw on the passengers side top, just unscrew that and fill until air comes out.

 

I do have a bleeder screw and I undo that whenever I need to fill. If it is an air bubble that is stuck somewhere, how can I get that out? Just park the car on a steep hill (nose up) and fill? Or any tips? Does it need to some tool like for bleeding brakes?

 

Thank you very much.

[idosubaru]

i wouldn't say "any darkness" in the tank since age can land plenty of debris in there.

 

no special tools. look up "burping" on here, that's what it's called to get the air bubbles out.

 

if it drove for a long time though it should have been fine and i doubt that's your issue. air bubbles don't just randomly appear on a perfectly fine running engine.

 

i'm betting headgasket, but hope it's not of course. it's common.

 

buy one of the vent-release radiator caps at an autoparts store. if that works to keep it from overheating then it's your headgaskets and it'll allow you to drive it for awhile as it allows the pressurized exhaust gases blowing into your coolant to escape.

 

don't let a mechanic try a compression test, these don't fail that way and I can almost promise you it will past, most of them do.

[Fuzpile]

The clue about the heater blowing cold indicates a piece of gasket has lodged in that loop or as gary explained a severe air bubble in the system.

As a backdrop when I got my Legacy it was leaking from the waterpump bigtime and I didn't know it, buying in the drizzle. Only one of the two fans were working then and kept the engine from frying.All is corrected now but at point of overheat i coulda run the heater to decrease the engine temp.

Some vehicles have the heater lines as part of the system. That's another matter. The core needs opened up by control and system bled of air again.

I Know you didn't position the thermostat wrong. Giz twd engine, right:)

[nipper]

Hey,

 

Have a quick question (hopefully).

 

I have a 97 subaru outback and when I drive, the cooling system seems to just shutoff and let the engine overheat.

 

In the morning, when I start the car, it starts up fine and warms up fine, and stays at a good temperature. The heater works and the engine temperature levels off where it should. Then, after about 10 - 15 minutes, my heater begins blowing cool air and the temperature skyrockets.

 

I have plenty of coolant and no leaks and I just changed the thermostat since it was due anyway, but there is no change. I also had both the radiator and water pump replaced 6 months ago, though I would not be too surprised if they were not installed properly.

 

Anyone have any ideas, or if there is any other info that could help?

 

Thanks,

 

 

This does not bode well, but before i become Dr doom...

 

Did you use a Subaru t-stat? If not go get one and install it. replace the radiator cap as it is old enough to be replaced.

 

refill cooling system.

 

remove cap

start car

slowly pour in coolant with car running

stop when full.

wait for car to warm up

When the water surges out the radiator, that is the T-stat opening. Wait till it settles down and add more coolant

put cap on

Fill overflow tank

take a short drive.

let car cool down

check fluid levels

 

If needs more coolant repeat.

 

This is the proper way to fill any cooling system. If you still have the same issue, well, we will cover that later.

[GeneralDisorder]

You have blown head gaskets - I noticed you are in my area and I replace these often - if you would like some help with your problem I would be happy to take a look at it and give you an estimate, etc .

 

Basically - the engine has to come out of the car - and there are some other services (valve adjustment, etc) that should be done at the same time. It's also an opportune time to replace leaking oil seperator plates and bad clutch's, etc.

 

It is not a stuck air bubble if you are using the bleeder screw when filling it and the car is level or nose-up. With the bleeder out you just fill till it comes out the bleeder and you are done. If it overheats after that it's not due to an air bubble.

 

99.5% of the time - the symptoms you outlined are indicators of head gasket failure on that engine. It's very, very ,very common - so much so that these engines rarely make it past 150k (somtimes not past 50k) without blowing them. The good news is that the replacement gaskets from Subaru are excelent and the problem will never return.

 

If you have not done so - you need to change the oil. When the engine is overheated the oil breaks down - this will contribute to rod bearing failure down the line. Then you will be looking for a new engine and you will be very sad

 

Contact me - I can save you a lot of money and frustration. And if it turns out that you just have a more simple cooling system problem then it will be a simpler, cheaper fix - though I doubt that's the case from your description. My email: cropper(at)gmail(dot)com.

 

GD

Edited November 11, 2010 by GeneralDisorder

[bstone]

GD, do you ever do HG jobs with the engine still in? Obviously easier to take it out, but curious. Yeah also can replace the PCV Plate and the rear main seal if it's leaking.

[idosubaru]

Did you use a Subaru t-stat?

yes, they did:

Yes, I used a subaru one, .

from when i asked.

[GeneralDisorder]

GD, do you ever do HG jobs with the engine still in? Obviously easier to take it out, but curious. Yeah also can replace the PCV Plate and the rear main seal if it's leaking.

 

No - while it technically can be done, it is VERY not fun and the issue is primarily one of cleanliness - you just can't do a good enough job of cleaning block surfaces, etc with coolant dripping out of the engine, and the chance of damage to the head or block surfaces or to the new head gasket durring installation is higher. Removal of the engine saves as much time as it takes and the end result is higher quality - also that oil seperator plate, etc is pretty much a deal killer for doing the EJ25D head gaskets in-car - why skimp out on a $37 part that will stop a major oil leak?

 

GD

[bstone]

GD, I do wish you were not on the other side of the country. I have some electrical oddities that would love your attention.

[GeneralDisorder]

Electrical is a lot of fun . PM me if you like - I'll help as best I can from this distance.

 

GD

[idosubaru]

electrical....hmmmm....fun.

[Ore Ele]

You have blown head gaskets - I noticed you are in my area and I replace these often - if you would like some help with your problem I would be happy to take a look at it and give you an estimate, etc .

 

Basically - the engine has to come out of the car - and there are some other services (valve adjustment, etc) that should be done at the same time. It's also an opportune time to replace leaking oil seperator plates and bad clutch's, etc.

 

It is not a stuck air bubble if you are using the bleeder screw when filling it and the car is level or nose-up. With the bleeder out you just fill till it comes out the bleeder and you are done. If it overheats after that it's not due to an air bubble.

 

99.5% of the time - the symptoms you outlined are indicators of head gasket failure on that engine. It's very, very ,very common - so much so that these engines rarely make it past 150k (somtimes not past 50k) without blowing them. The good news is that the replacement gaskets from Subaru are excelent and the problem will never return.

 

If you have not done so - you need to change the oil. When the engine is overheated the oil breaks down - this will contribute to rod bearing failure down the line. Then you will be looking for a new engine and you will be very sad

 

Contact me - I can save you a lot of money and frustration. And if it turns out that you just have a more simple cooling system problem then it will be a simpler, cheaper fix - though I doubt that's the case from your description. My email: cropper(at)gmail(dot)com.

 

GD

 

Thank you, and everyone else that helped.

 

I have a brother in law that is a mechanic for Carr Subaru over in Beaverton and he does all my work for me, labor free (I do his taxes for him), and my grandpa has a garage over in Hillsboro (by Intel) so I only have to cover parts.

 

Thank you again.