Air in cooling system after numerous bleeds, but no loss of coolant? - Page 2 - Subaru Outback - Subaru Outback Forums
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post #11 of 19 (permalink) Old 02-22-2019, 08:18 AM
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This EJ is NOT prone to overheating events. That is just plain wrong.

Here's a rundown on coolant and engine temperature. Light science.

The system is sealed and and pressure contained via the radiator cap which helps keep the coolant from boiling even when reaching the boiling point. The cap vents excess pressure that builds in the system to the reservoir, anywhere between 13 and 19 psi depending on your cap, and when the system is cooling, the cap allows for the fluid in the reservoir to be pulled back in to the system.

Coolant and water expand with heat creating the pressure.

The thermostat maintains engine block and head temperature by containing the coolant in the block and allowing the coolant to flow through the radiator, starting at about 175F. This allows the pump to pull in a cooler blend of coolant and mix with the coolant in the block. This is a constant opening and closing of the thermostat after the engine reaches operating temperatures. If the thermostat is the wrong type, then flow is restricted, temperatures rise, pressure rises and the cap allows the coolant to flow out excessively until the coolant either fills or overflows the reservoir.

Now, on the OP's issue, it seems to me that you have a head gasket issue. What ever caused it, it's up in the air at this moment. I don't think you are not losing coolant. Are you checking the radiator or the reservoir level? The number one way air gets in the system is through a breech in the head gasket. If it has a leak, the pressure in the cooling system will push the coolant out, not suck it in while the engine is running. You would see spots on the ground where you park if it's heavy enough. The only time a system can pull in air through a leak is when the coolant contraction creates a vacuum on the system and air is pulled through the cap either due to a reservoir hose leak or the reservoir is empty. Sometimes through a weak clamp/hose connection somewhere at the top of the engine. But again, you would also see signs of a leak due to pressure pushing fluid out when the engine reaches temp and pressure rises.

There is a difference between seeing fluid come up in the funnel and air bubbling. When the fluid expands with the cap off and a funnel in the neck you will see a rise in the fluid in the funnel when the thermostat opens. It will flow up like water from a garden hose in a bucket. No air, just fluid circulation. When you have repeated tried to burp the system and you continually get air bubbles after some time and repeated thermostat operation, it's HG time. The heat at one moment and no heat at the next is a sign that the coolant is low and there's not enough in the system to maintain proper flow through the heater core. The temperature door motors on these cars don't fail. They last seemingly forever. My 99 went 300k miles without one HVAC part needing replaced. My 01 has 215k miles and no issues with the HVAC system components in the cabin. My 10 has 167k miles on it and it's the same. No problem. So I would inquire to the previous owner if you can concerning the brand and type of HG that was installed. Did a shop do the work or did he/she do it themselves? Was the head checked for cracks, plane, etc.? If the Heads weren't torqued down properly, you could have an extremely slow breech that over time turns in to a large breech, such as what you describe points to, and this issue may have been there from the beginning.

Pressure test the coolant system with a proper tool. Build the pressure to 18-20 psi and wait. If the pressure drops, there's a leak. If you don't see fluid dripping externally, then that means it's internal. If/when the pressure drops, and it's been about 10 minutes, start the car with the pressure on the system built back to 14-18 psi and see if it smokes. Even if it doesn't smoke out the tailpipe, you could still have a HG leak or crack in the head. My 10 didn't smoke a bit and coolant was getting in to cylinder #1. I know this because when I took the engine apart, cyl 1 was squeaky clean. No carbon on the chamber or valves because the water steamed it off.

Just sayin'. Looks like HG. Be sure to get MLS gaskets and check the heads for cracks, especially the one that is covering the clean cylinder, the overall plane of the heads and make sure everything is clean and all remnants of the old gasket removed prior to reassembly.

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post #12 of 19 (permalink) Old 02-23-2019, 05:19 PM
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Quote:
Originally Posted by cardoc View Post
This EJ is NOT prone to overheating events. That is just plain wrong
nope, you’re wrong....if that’s how this needs to be discussed!?

To be clear I was speaking of 2010 EJ headgaskets modes, not just the engines in general. I don’t mean they’re prone to overheat. but that the initial symptom on 2010s, unlike 00-09s, can be overheating. Seems obvious to me. In any event the first sign of headgasket failures on this exact engine which this OP owns could overheating. Because:

Replaced EJ headgaskets that fail, have symptoms like this more than factory installed.

Also factory 2010’s have it happen more often than 00-09s. A google search shows 2010’s overheating being an initial headgasket symptom. This particular failure mode seems more prominent on 2010s.

https://www.google.com/search?q=2010...&client=safari

https://www.google.com/search?q=2010...iw=320&bih=529


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post #13 of 19 (permalink) Old 02-25-2019, 09:07 AM
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@idosubaru Your post is, "That year is also prone to random, not easily diagnosed, overheating events which make it prone to multiple or excessive overheating, which is bad."

This statement is FALSE.

Maybe I should explain this further.

The 10s up don't have a temperature gauge, but instead use a warning light that is blue on initial cold start and goes out as the engine temp comes up. If the engine runs hot, the light comes on red, but by then it's too late.

It's been my experience with these engines, the EJ253 of all generations, is not prone to overheating unless a failure with a hose or cap allows for coolant loss, a thermostat starts working, or rather not working, sporadically, or a cooling fan stops functioning.

Sometimes a single overheating event causes a head gasket breech, sometimes it takes more. The head gasket design is poor, we all know that, but the failure with the head gasket is the oil leaks caused by the corrosive nature of the oil eating away at the bonding material, not the coolant. The oil ports are on the outer parameter of the head while the coolant ports are in close to the cylinder, so the oil issue does not directly affect coolant seepage in to a cylinder. But if you look at the bonding material of the gasket, it is incapable of keeping a seal when the temperatures get too high and the expansion of the metals allows for easier breech events. The engine and gasket material is designed to withstand temperatures to a certain point and it is assumed by the engineers that the owner will be attentive to the car and what's going on. By this I mean regularly checking the simple things like oil and coolant level and being observant for any signs of a leak.

And in case anyone reading this does not know it, oil helps control engine temperature and if the level is low due to a breech in the HG or otherwise you lose lubrication and get an increase in friction - which creates heat - and the oiling system's ability to transfer the heat. Low oil levels increase combustion temperatures due to high cylinder wall temperatures and piston heating. This can create an environment for knocking/detonation and higher fuel consumption. Low oil also creates high temps on the bearings and all moving parts. This heat transfers to the surrounding metals in the engine and the coolant system has to keep up with it.

This is why when you replace the head gaskets on an EJ you go back in with the MLS gasket and not the OEM. It gives you a broad range of protection in not only containing the oil but also with the expansion of metals at high temperatures should the car overheat.

The engine is not prone to overheating unless there is a failure in temperature control due to leak, thermostat or cooling fan operation; many times these things in conjunction with low oil level are the cause for HG failure that allows for a coolant leak in to a cylinder.

As for overheating after an HG repair, if the person who performed the repair did not do a thorough job, then yes, a repeat will occur somewhere down the road. You can't use a Google search as justification for an incorrect statement and belief. You could find all kinds of misinformation on a Google search and it still comes down to the ability of the person attempting to diagnose the issue, whatever that issue may be.

I have a 2010. I bought the car knowing it needed repairs. The owner advertised it as having a leaking heater core which is a 4 hour repair plus the cost of the core. It also had other issues that were apparent at the time. The heater core is not leaking. I replaced the hoses his "mechanic" removed and there's no leak. I also did some checking around and found that the thermostat was also removed, apparently to keep the cooling system from building pressure. The head gasket was leaking in to cylinder 1. The "mechanic" could not isolate a head gasket issue because he did not know what to look for in locating the exact cause for the coolant loss and overheating. That is a failure on the mechanic, not the engine. What caused the breech in the first place? Could be anything like I've mentioned above. The HGs were leaking oil, there are fairly new coolant hoses and clamps on the system.

It's not the engine. It's the guesswork that goes along with inexperience or ignorance - sometimes laziness - in diagnosis. Nothing is hard unless you make it hard.


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post #14 of 19 (permalink) Old 02-25-2019, 10:33 AM
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Quote:
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@idosubaru Your post is, "That year is also prone to random, not easily diagnosed, overheating events which make it prone to multiple or excessive overheating, which is bad."

This statement is FALSE.
I agree 100% those were poor word choices. In the end my point was leading to caution the OP to confirm via diagnosis rather than guess. Some people will see a 2010 with no external leaks and think the HG's are fine, that can also be inferred by DIY folks scouring the interwebs. I'm just cautioning not to do that. It's like the familiar - "no oil/coolant mixing", "compression tests good", "liquid exhaust gas test negative" - therefore the headgaskets must be good.

Confirmation by diagnosis is needed, not just a few checks which could be false negatives.

In my experiences - 2010's, while not at all common, when they due have headgasket failures they can fail internally more often than 00-09's. This creates some false negatives.

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post #15 of 19 (permalink) Old 02-25-2019, 11:51 AM
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As I've said before, I'm betting it's not a HG leak. Did the OP try to forward and reverse flush the heater core?

If you hear a "babbling brook" sound coming from behind the dash as you accelerate, there is air in your heater core and it's also likely there is a blockage in there and/or elsewhere in your cooling system. If the hoses deteriorated and sent pieces of rubber through the cooling system, they can get caught in the heater core or perhaps the HG passages. I haven't handled my Gen 3 HG's I had a shop replace mine when they began to weep oil. I have had to do a HG job when there were pieces of deteriorated rubber hose blocking the HG ports in another car causing localized boiling of the coolant. It looked just like a blown head gasket except there was no exhaust in the coolant, just coolant getting pushed into the reservoir and the symptom was drastically reduced when I ran the A/C full time (it kept the radiator fan running and kept the coolant at a lower temperature).

I had to remove the head and this is what I found. 3 ports around 1 cylinder clogged. This caused localized boiling and "air" getting into the system. The HG was in perfect condition and the head was perfectly flat but I had do essentially do a head gasket replacement anyway to get down to this and fix it.



You should first remove the heater hoses and do a forward and reverse flush of the heater core to see if anything comes out.
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post #16 of 19 (permalink) Old 02-26-2019, 12:14 AM Thread Starter
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Originally Posted by rsrocket1 View Post
As I've said before, I'm betting it's not a HG leak. Did the OP try to forward and reverse flush the heater core?

If you hear a "babbling brook" sound coming from behind the dash as you accelerate, there is air in your heater core and it's also likely there is a blockage in there and/or elsewhere in your cooling system. If the hoses deteriorated and sent pieces of rubber through the cooling system, they can get caught in the heater core or perhaps the HG passages. I haven't handled my Gen 3 HG's I had a shop replace mine when they began to weep oil. I have had to do a HG job when there were pieces of deteriorated rubber hose blocking the HG ports in another car causing localized boiling of the coolant. It looked just like a blown head gasket except there was no exhaust in the coolant, just coolant getting pushed into the reservoir and the symptom was drastically reduced when I ran the A/C full time (it kept the radiator fan running and kept the coolant at a lower temperature).

I had to remove the head and this is what I found. 3 ports around 1 cylinder clogged. This caused localized boiling and "air" getting into the system. The HG was in perfect condition and the head was perfectly flat but I had do essentially do a head gasket replacement anyway to get down to this and fix it.



You should first remove the heater hoses and do a forward and reverse flush of the heater core to see if anything comes out.
Thank you, this honestly seems like the most plausible explanation given my symptoms: no coolant loss, gases appearing in coolant without an indication of combustion gases present, and occasional overheating.
I was thinking of hooking up the $5 easy flush kit or whatever it's called from prestone, but I'll have to look into a more proper reverse flush. There's a new shop in town that specializes in subaru that's been recommended to me, I might have him take a look as well. I'll report back whenever I get this resolved.
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post #17 of 19 (permalink) Old 02-26-2019, 12:52 PM
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Some garages have a pressure based flush system where they pulse compressed air during flushing. They claim it will "pop" out stuff like I showed but the cooling system is not meant for pressures much higher than 20 psi so a hammer in pressure may cause damage to delicate things like an old heater core. Prior to tearing down to the head gasket on this car, I first tested everything I could to see if the problem was a blown headgasket (chemical block test, pressure test, individual cylinder compression test) and nothing pointed to external air or exhaust getting into the coolant.

I then got a 3300 gpm sump pump and ran it with a variac to control the pressure. I eventually ran it full speed for several sessions up to 8 hours at a time using water alone, water with a little cascade dishwasher detergent and water with lemishine (citric acid). None of these stopped the generated gases but driving patterns seemed to make the most difference (low temperature thermostat with a 1/8" hole drilled through it, running with the radiator fan running full time and running the cabin heat full blast any time the engine ran at high RPM's followed by a stop light).

I eventually broke down and learned how to remove the head and check and replace the HG and that's when I found the blockages. It was a 2 weekend job with a few hours extra during weeknights but it completely solved the problem. It was less than $100 in parts but it was quite the experience.
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post #18 of 19 (permalink) Old 03-03-2019, 12:46 AM
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I have been experiencing very similar things with my 2006 2.5 recently, and found all of these messages to be quite enlightening. I'm no mechanic but I'm always trying to learn more and become better, so dealing with this problem has been a major headache. I'll explain what happened to me and what I've done so far to fix the problem, as well as add what I'm going to next (after reading the useful information here) and I'll let you all know how it goes.

Day 1 Notice white trailing behind me on the freeway, move to the exit as coolant gas spews from the hood. The top radiator hose had popped off because the manifold was broken (most likely from the shop I bought it from, making a quick repair rather than the proper repair). I popped the hose back on and made it 10 miles back home, having to pull over twice to put it back on and eventually getting my neighbor to tow me home the last mile.

Day 2 Buy "top end" replacement radiator, install it, fill it, run it. Overheats. Did some research and found out I have to burp it (bear with me here, I'm learning) So I had someone bring me a no spill funnel. Burped it for a half hour, heat came back on, went for a drive, everything seemed fine.

Day 3 Drive it to work in the morning, 20 mile commute. Everything is fine until the last block, where the heater gets really hot, then ice cold, and the engine temperature starts to rise. It sits all day, I start to drive home cautiously. Everything is fine when the engine gets to running temperature. Heater is working normally, temperature is staying constant. Then bam, overheats. Can't figure it out, called a tow truck.

Day 4 (We live on a farm 10 miles from town, and share one vehicle between my wife and I. Having no car is no joke, we are starting to struggle.) Buy and install a new thermostat. Fill with new coolant, burp for 30 minutes both on flat ground, and then front end raised. Everything seems normal, engine temperature constant. Pop it into reverse for a test drive and the temperature bumps up a bit. I get a minute down the road and have to turn around because the temperature is rising too fast.

Day 5 My uncle is a professional mechanic. He comes over to help me diagnose the issue. We put the car on an incline, attach the no spill funnel and run the car. (I should mention here that every time I opened the radiator during this process, even when the car had cooled for 24 hours, a large gas bubble burst coolant everywhere.) We run the car, get it up to temperature, lots of bubbles are coming out. I've got the heater cranked and it's cold air, still more bubbles. I rev it to 2500RPM for about 5 minutes as the temperature climbs, and the fluid in the no spill funnel rises closer to the top. Still bubbles keep coming. We shut the car off and he tells me I've got a head gasket leak, pulling exhaust (or air) into the coolant system. I'm devastated since I just spent all my savings moving to a farm and now have no car. So as a last ditch effort I try "Blue Devil" Head Gasket Sealant. I follow the instructions to a T, emptying out a bit of coolant with a syphon (my radiator doesn't have a drain valve) and start pouring it in. For some reason it tops off the radiator right away, which is frustrating because I've already started pouring the product in, and now I have to remove more fluid. So I let some out of the bottom hose, started the car and poured the rest in. The product says to run it for 50 minutes at normal temperature. Well by the time 25 minutes had elapsed the car was dangerously close to the red zone, so I figured the product wouldn't work. I threw in the towel and managed to find a dealership that would get me into a newer car.

So then I come home with my new car, 6 hours after that Blue Devil has cooled down, and decide to go for a test drive. Heater comes on quick, temperature stays normal, and I go cruising down the road. Seems like the problem has been temporarily fixed! Only now, the heater only blows hot from the drivers side. I forgot to burp the system again before test driving it tonight, but it handled fine and didn't hint at overheating. So I got on this forum to find information about the heating only blowing out of one side and came across this thread, with very valuable information.

So, with things sitting as I've just described, I intend to put some clamps on the overflow hose into the the reserve tank, flush the heater core, and replace it with subaru specific coolant and conditioner. Of course these are the things I plan to do while I get my ducks in a row to change the head gasket. If these become a solution to the heat only coming out of one side, air entering the system, and intermittent overheating, I'll let ya know! Thanks for the good info!
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post #19 of 19 (permalink) Old 03-03-2019, 10:20 AM
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Welcome Jared, I don't think you need a new headgasket.
  • This generation of Outbacks tend not to have headgaskets blow between the cylinder and the cooling system. The leaks tend to be simply weeping of oil to the outside of the engine.
  • No heat means hot coolant is not circulating through the heater core.
  • Coolant bursting out the radiator cap from a cold engine means air did not work its way up to the radiator cap and the system is still pressurized at up to 15 psi assuming your radiator cap is functioning properly
  • If you didn't have a headgasket, radiator or heater core leak, the Blue Devil stuff will simply add another variable in any further troubleshooting because it clogs things up when it gets a combination of heat and air which is how it's intended to work

BTW, I've also had to replace my radiator after having the top hose blow off twice. It was on the second time that I noticed the end of the radiator inlet had broken off and there was nothing holding the hose on other than the friction of the spring clamp.



Fortunately I was able to simply reattach the hose, fill the system up with water and make it home without any problems.

If you want to discuss this more, it would be a good idea to start a separate thread so that the troubleshooting doesn't get crossed up with the OP's situation.
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