1999 2.5L Over heating no leaks.

[Reloadit]

This summer, my 1999 Outback over heated on a fishing trip and it seemed to have dumped much of the fluid into the overflow reservoir which in turn overflowed in the engine compartment.

 

I managed to get it to suck the overflow back and and topped it off with filtered water to get myself home.

 

I replaced the thermostat with a fail safe that supposedly stays open if it fails.

 

After several months it did it again today. When I replaced the thermostat, I spent a week burping and bleeding the air out but then I got lax and stopped checking after a couple of weeks of the level holding steady. I don't get the feeling I am leaking fluid, I sure don't see any leaks.

 

I put a pressure tester on it today and it took about 10 minutes to go from 15psi to 14psi with no sign or sound of leaks. I tested it without the car running.

 

The oil is clean, no off colored exhaust. No loss of power except with a nagging hesitation during the hottest months when I start it up when it is already at operating temperature and then take off it will hesitate then which has been a long running problem.

 

I'm just wondering if there is something that would malfunction and cause the overflow reservoir to unnecessarily draw coolant out of the radiator causing my problem or if it just stands to reason I have a tiny leak and eventually it gets low and then BAM overheats, dumps into the overflow and spews out of the overflow?

[doublechaz]

Could be a sketchy radiator cap. Part of it's function is to build pressure in the system so it doesn't boil as easy, but not so much pressure that your hoses pop. When pressure gets high it dumps into the bottle, and is supposed to suck it back when it cools. Perhaps the cap has something borderline with the spring and gasket that makes it dump to the bottle easier sometimes than others. EDIT: I did see a video where an after market radiator had the filler made wrong so the cap could not possibly seal correctly. I think that was Uncle Tony's Garage. Just to say that all parts these days are junk and we have to second guess them.

 

If the system was actually tight you could go over night without losing a PSI. That could be the cap. It could be something else. If you put that pressure in with the system actually full of coolant and no coolant comes out on the ground or into the cylinders or oil, then I would say it is the slight bit of air above the water going out from the cap to the bottle. It could also be something about the test gear you are using as well.

[Reloadit]

Could be a sketchy radiator cap. Part of it's function is to build pressure in the system so it doesn't boil as easy, but not so much pressure that your hoses pop. When pressure gets high it dumps into the bottle, and is supposed to suck it back when it cools. Perhaps the cap has something borderline with the spring and gasket that makes it dump to the bottle easier sometimes than others. EDIT: I did see a video where an after market radiator had the filler made wrong so the cap could not possibly seal correctly. I think that was Uncle Tony's Garage. Just to say that all parts these days are junk and we have to second guess them.

 

If the system was actually tight you could go over night without losing a PSI. That could be the cap. It could be something else. If you put that pressure in with the system actually full of coolant and no coolant comes out on the ground or into the cylinders or oil, then I would say it is the slight bit of air above the water going out from the cap to the bottle. It could also be something about the test gear you are using as well.

 

Guess who is going to buy an OEM radiator cap. I replace the cap when I replaced the thermostat and it was a Napa cap with the quick pressure release which I wasn't super confident in that.

[Infosecdad]

For thermostats and radiator caps I only go OEM, there are so many stories of aftermarket not working correctly.

[Reloadit]

For thermostats and radiator caps I only go OEM, there are so many stories of aftermarket not working correctly.

 

Yes, I get the feeling I should have waited for the OEM thermostat. The dealer had neither the cap or thermostat in stock when it started acting up. I ordered the cap yesterday and should be in tomorrow. It would probably behoove me to go ahead and have them order the thermostat and pay the extra $25 for it.

 

I get the feeling it was the cap all along causing my problems but will know for sure in a three or four months of the new OEM cap.

[silverton]

Even fail safe thermostats that are supposed to fail open, can and will fail closed. They all close at some point right? Which means they all don't open at some point. If your system holds pressure I'd be looking at the thermostat and/or the radiator cap.

[doublechaz]

I should point out that I held a "top quality" Napa tstat next to a Subaru Genuine tstat. The part that opens was half the size on the parts store unit as on the OE unit. Only run a dealer tstat. The parts store unit did lead to temps in the 205 to 220 range where the OE unit runs 175 to 190.

[Reloadit]

Well, I guess that settles it, if they ever get my cap in I will order the thermostat.

[Reloadit]

Update, I replaced the thermostat and cap with OEM from my local dealer and the temperature at operating temp is slightly lower on the gauge and I haven't had any issues for a few weeks now but with it being cooler can't know if she will overheat again or not.

 

A buddy suggested I do a full radiator flush, adding the solvent and doing it. He thinks it will clean out settled muck that could plug up the system causing it to dump coolant into the reservoir leading to the over heating.

 

Before I do something like that, I would like to get some opinions on a full flush. I don't want to make matter worse. As far as I can tell there has been no stop leak in the system.

 

I could just wait until it gets scorching hot again and see if it ever happens again, but my buddy thinks the OEM thermostat and cap wouldn't have been the problem, but he has been known to be wrong before.

[doublechaz]

I wouldn't have thought the TStat could do this either until I lived it. There isn't much in a Subaru to make muck in the system. Aluminum block and heads, aluminum radiator and crossover pipe. Rubber hoses. If it was a 1970 iron V8 I would vote for flush it, in this case I would let it ride and keep an eye on it.

[Reloadit]

I wouldn't have thought the TStat could do this either until I lived it. There isn't much in a Subaru to make muck in the system. Aluminum block and heads, aluminum radiator and crossover pipe. Rubber hoses. If it was a 1970 iron V8 I would vote for flush it, in this case I would let it ride and keep an eye on it.

 

And that's exactly what I was thinking while my buddy was telling me about the flushing of his v-8s. I will let it ride and see how she does. Thanks again DC.

[Reloadit]

Hey fellas, I made it to the bitter cold this winter without any issues and then when it got to the point of remaining below freezing for a couple of weeks, I overheated on a 20 minute trip to the frozen desert to shoot.

 

After a couple of weeks of burping/checking the fluids, taking fluid out of the overflow and putting it back into the radiator, I'm at a loss.

 

It's a factory OEM thermostat and cap not a year old. This morning I sucked the fluid out of the overflow before starting my car. I have a line on the overflow tank that I can actually see the level. I opened the radiator cap and it did have a vacuum and it the fluids seem low. I decided to drive it to work and though it didn't overheat I did lose heat for a second at a stop light. Drove the 10 miles to work and the overflow fluid was still on my mark so it didn't dump any.

 

I'm still not seeing any leaks or fluids on the ground outside of the pouring out of the overflow when it overheats. Oils seems fine, exhaust seems fine.

 

I've been pulling the plug above the top house and filling through it as well as through the radiator cap. Whenever I try to warm it up with the cap off, it starts dumping fluid out of the cap hole. I've never seen the fluid circulate in this car.

 

The waterpump should have been replaced when the mechanic shop replaced the timing belt, they were paid to replace it.

[doublechaz]

Sounds like you have covered a lot of bases.

 

The small tube from under the radiator cap that runs in to the overflow should extend to the bottom of the overflow tank without any holes. If it does not go to the bottom of the overflow unbroken it will not be able to pull coolant back from there into the radiator when it cools. That could make it push into the overflow, fail to draw it back, puch more the next drive cycle, etc.

[Reloadit]

Sounds like you have covered a lot of bases.

 

The small tube from under the radiator cap that runs in to the overflow should extend to the bottom of the overflow tank without any holes. If it does not go to the bottom of the overflow unbroken it will not be able to pull coolant back from there into the radiator when it cools. That could make it push into the overflow, fail to draw it back, puch more the next drive cycle, etc.

 

I will take a very close look at the hose today. I did make it home and back to work this morning without changing the coolant level in the overflow. The bleeding air/burping seems to be a tedious undertaking regardless.

 

Thanks again and I will let ya know what I find.

[doublechaz]

If you can find some place steep enough, a very steep uphill angle while parked can help burp it. I mean a deal steeper than if you are on level ground and drive the front wheels up on ramps. Maybe something like 18 inches higher at the front wheels than at the back wheels.

[silverton]

https://www.amazon.com/OEMTOOLS-87009-No-Spill-Coolant-Filling/dp/B01A2CQSU6

 

Something like this makes bleeding a much simpler process. Fill the bucket just over the ramp, run the car for 40 minutes or until the fans come on and then turn off, you can do that part twice if you want but just once is usually good enough. But it won't really matter how much you attempt to bleed it if air is getting in, say via the head gasket.

 

I believe there are test strips available at most auto parts stores that can check for combustion gases in the coolant, I'd do that and/or a leak down test, just to give myself piece of mind, or to know wtf is going on.

[Reloadit]

https://www.amazon.com/OEMTOOLS-87009-No-Spill-Coolant-Filling/dp/B01A2CQSU6

 

Something like this makes bleeding a much simpler process. Fill the bucket just over the ramp, run the car for 40 minutes or until the fans come on and then turn off, you can do that part twice if you want but just once is usually good enough. But it won't really matter how much you attempt to bleed it if air is getting in, say via the head gasket.

 

I believe there are test strips available at most auto parts stores that can check for combustion gases in the coolant, I'd do that and/or a leak down test, just to give myself piece of mind, or to know wtf is going on.

 

I looked the coolant overflow hose over and didn't see any damage so I cut off the end that connects to the radiator and reconnected it with a tighter fit in case it was lose there.

 

I ordered the coolant kit.

 

Maybe you or Double can explain the overflow normal behavior to me. Does fluid transfer back and fourth all the time?

[doublechaz]

It pushes into the overflow as it gets hotter. I would expect from a 2 gallon system about a pint. Then as it cools it pulls back in. If that overflow tube leaks it will pull air back in rather than coolant from the bottle. The radiator cap is also very important in this.

 

An ideal cooling system will have zero air in it. Water is very close to perfectly constant volume under changing pressure conditions. No compressible. It is not constant volume while liquid under changing termperature conditions. It has the smallest volume just a few degrees above freezing. We all know it gets a good deal bigger when freezing, but it also gets a little bigger as temperature goes up. This is why the warm water and cold water in a lake separate into layers, etc. This change is quite small, about 5% between freezing and just before boiling. But just like ice breaking pipes, it would break the block if it had no where to go. Hence the overflow tank.

Edited February 12, 2022 by doublechaz

[silverton]

There is a reason the coolant overflow has a 'full' line. as the cooling system heats up and cools down the coolant expands and contracts. the system needs a reservoir to pull some when it needs it, and then somewhere to put it when it's done with it.

 

If you are ensuring your reservoir is never higher than the full line, and it is still blowing coolant out, your cooling system is getting over pressurized. Either by a faulty radiator cap, thermostat, OR...blown head gasket.

[Reloadit]

OK, thanks fellas. I marked a spot on the overflow container up high enough so I could see the actual mark and tell if it is depositing coolant or extracting it more.

 

I'm 40 minutes after driving it right now and I am about two inches above the mark, one inch from overflowing the overflow container. I don't know when the suction occurs or if this excess in the overflow is just going to stay in the overflow or what.

 

Here is my question at this point. If I were to take the car to a dealership and have them give it a "makeover", do they have such a thing where they go in and replace all critical gaskets, hoses and censors or something and if not, what do you fellas recommend a man do. Mind you, it has a new timing belt, water pump and CV joints though I suspect they are somewhat defected because there is still a slight shimmy from 30-40mph.

 

That car only has 120,000 original miles and the head gasket was apparently changed at the dealer once before from the original owner.

 

I'm curious to know what should be done to keep this car reliable for my fishing and hunting adventures in the mountain often out of cell service and what one might or should expect to pay. Thanks fellas.

[doublechaz]

I would check that fluid level after it sits the night. It should be in the same place every drive cycle from full cold to full cold. It can take a surprising time to reach full cold.

 

Another item that can cause the overflow to not function correctly is the radiator cap and it's fitment to the radiator neck. I've heard of aftermarket China radiators where the neck is so far out of spec that no cap will function correctly on it.

 

The shake at 30-40 is likely wheels or tires.

 

If you keep your oil pan from fighting a rock for space the only things that should strand you would be hoses and belts. Those can be inspected and replaced. For oil seals I would keep an eye on it for leaks and only replace as needed plus carry some extra of each kind of liquid with you. Brake hoses and parts can be checkd and replaced as needed.

 

If you go to a dealership with an open ended list like that it will cost several times the value of the car. If you can find a reliable local independant shop it will cost about half as much. Hence my inspect and replace as needed policy.

[Reloadit]

I would check that fluid level after it sits the night. It should be in the same place every drive cycle from full cold to full cold. It can take a surprising time to reach full cold.

 

Another item that can cause the overflow to not function correctly is the radiator cap and it's fitment to the radiator neck. I've heard of aftermarket China radiators where the neck is so far out of spec that no cap will function correctly on it.

 

The shake at 30-40 is likely wheels or tires.

 

If you keep your oil pan from fighting a rock for space the only things that should strand you would be hoses and belts. Those can be inspected and replaced. For oil seals I would keep an eye on it for leaks and only replace as needed plus carry some extra of each kind of liquid with you. Brake hoses and parts can be checkd and replaced as needed.

 

If you go to a dealership with an open ended list like that it will cost several times the value of the car. If you can find a reliable local independant shop it will cost about half as much. Hence my inspect and replace as needed policy.

 

 

Thanks DC. Yesterday I hovered over the radiator with the cap off and RPM set at 2000 until it started circulating. I used a turkey baster to extract fluids before overflow. I ordered the kit Silverton recommended but seems like it must be out of stock because the arrival date keeps changing and Amazon gave me a refund for the same amount as the kit.

 

When the fans would kick on, the fluids lowered and I could put more fluid in but when they turned off, the fluid would start overflowing again. I ran it for 4 or 5 cycles where the fans kicked on, just adding and extracting fluid to keep it from spilling. I drove it before it cooled down completely and when it was cooled down completely, iced over windshield there was about 3/3-1 inch over the full line.

 

I'm going to keep extracting the overflow amount and adding it back to the radiator and if I do get the kit as it still says it will be delivered Tuesday, I will hook that up and let it run and burp until it's 2.5 heart is content.

 

I do have one question on this kind of burping/bleeding. Do I put the cap on while the car is still running or turn it off and cap it?

 

Oh, and about the shimmy, we have beat that up here too and it started right after I had the CV joints replace which the shop got the wrong ones and installed them and then had to get the right ones. At the same time I did put on new tires and the tire store has checked everything over and over and maintains it is not the wheels or tires. Took it back to the used car dealer I purchased it from and who did the CV joints and they said they couldn't find the cause of it, they felt it but said to bring it back in if it gets more obvious.

[doublechaz]

You want the cap on as it cools so the suction thing will happen. Beofre or after shutdown shouldn't matter if you are talking a minute or so.

 

I remember the shimmy talk now. I wouldn't think the half shaft would be able to make much vibration unless it was visibly bent. But then the wheel shop should be able to identify a bent wheel while checking balance. So I don't know how this isn't solved yet.

 

I did learn a new one just the other day. Some wheels are positioned by a precision bore in the wheel and a precision shoulder on the hub and the lugs just hold it on. Other wheels are positioned only by the cone of the lug nuts. In the latter case, if you use the wrong design of lug nuts the wheel won't be centered relative to the axle so it will never really balance.

 

There are at least three designs of lug nuts. Two different angles of cone, and another that doesn't have a cone, but rather a sort of threaded tube that goes inside the wheel hole and a flat that must be matched with a washer. I've only ever seen the last kind on magnesium wheels. I believe the two cone designs are for steel vs. aluminum wheels.

[Reloadit]

Hey DC, after I let the car run and get to full temp and cycle with the cap off as mentioned before, it overheated again and filled the overflow reservoir.

 

Now, my funnel coolant filling kit came in the day before after waiting a month for it to show up from Amazon and I have used it. I let it run and cycle with the funnel 1/3 full which clearly allowed it to burp and bleed the air. I could see tiny tiny tiny little air bubbles pretty much the whole time.

 

After running it for another 40 minutes at operating temperature with the fans kicking on and off I squeezed the top hose plugged the funnel and then put the cap on and turned to car off per directions of use.

 

It has kicked out about 3 cups of coolant into the overflow over the past few days. It kicked most of it out after some 80mph freeway driving. It hasn't overheated. I have extracted the overflow without putting it back into the radiator. I was planning on seeing if it keeps kicking coolant out or if it was just too much coolant from the funnel filling kit.

 

If it turns out I have gas leaking into the cooling system and I decide to get it fixed what would be the wise job/overhaul to have done while it is torn apart and what kind of warranty should I be expecting to get for this kind of work.

 

I could buy a new Subaru but if I had my choice I would rather have my 99 over my wifes 2014. It has only a total 0f 122000 miles on it. I've looked at rebuilt engines and I have seen the engines from Japan available.

 

Just trying to get some ideas of my options and what to expect. I sure can't sell it without disclosing the issues.

[doublechaz]

If it has a head gasket leak the options are all pretty expensive if you don't do much or all of the work yourself.

 

A same year engine swap is easy if you can get hold of an engine you can trust, but that is the trick.

 

Going to a different year engine can get in to mismatch of sensors and things like that which can make it more difficult.

 

Head gasket repair isn't like building a rocket, but there is plenty of room for a shop to add in costs. If you have a good shop or friends you can trust on the project it shouldn't be too bad. I would pull the engine to do the work. Get the heads off and clean the surfaces. Check the heads and block for straight. Machine shop if necessary. New MLS gasket. Back together. Of course there are lots of steps and details to talk about on that path.

 

My local yard is run by theives, but if you have a good local yard then it's close to ideal to find a car that was running great and is at the wrecker's because it was Tboned recently. Pull the whole engine and swap in a weekend. Unfortunately that's not very likely with a car this old.

 

There is a test you can do on the coolant to check if it has exhaust gas in it. Put a little in the provided bottle, add a test chemical and check for a color change. It's cheap enough to be warranted before getting in to serious repairs.