Blown head gasket?

[blkchr91]

I have posted here in the past but never seem to have any luck...I'll try again tonight.

 

I was driving my 04 FXT on the highway at around 70 mph and went to pass someone. I was greeted by billows of white smoke from the engine bay. I looked down and noticed that the temp was where it normally sits...just above a quarter. 

 

I immediately shut it down and had it towed. 

 

I got it home and found the upper radiator hose had a split that was 3 inches long.

 

Last week before this happened, I smelled coolant when pulling it in (again no overheating at all).

 

I shut the car down and popped the hood. There were dime sized bubbles going in the overflow with the vehicle turned off that persisted for a few minutes.

 

On the morning before I took off, I noticed that the overflow was almost empty but I drove it anyways since I had no choice. 70 miles later, the incident happened.

 

I went and got a fresh set of Mishimoto Upper and Lower radiator hoses. 

 

The upper hose might have been the original, but looked to be in otherwise great shape.

 

I used the Lisle funnel to bleed things after refilling with the old coolant (which looked fine) and adding a mix of distilled water and Peak Global to top it off with.

 

I idled it for about 15 minutes until the bubbles stopped. I held it down between 2k-3k rpms for about 5 minutes and the bubbles stopped.

 

However, when I rev it I get bubbles.

 

Seems like a small breach that is going to get bigger over time. 

 

Most people wouldn't notice this because they lack the Lisle funnel or don't go through the extra step of revving the engine just to see what happens.

 

FYI, Water Pump and Thermostat are all only about 5k miles old and the T-Stat is OEM.

 

My Tribeca started with the same symptoms and 6 months later is nearly undriveable.

 

This is what my radiator pressure tester says while using it running (on the radiator filler tank which is external to the radiator since it is a turbo)....sitting at 27 psi while idling!

 

I don't understand how it can be be anything else besides a head gasket based on this but then again no one seems to use a radiator pressure tester dynamically as a test. 

 

My only doubt about the validity of this test is that no one seems to bother doing this test.

 

Is this a valid test? Head gasket HAS TO BE toast if I understand this correctly.

 

 

Thank you.

Edited September 13, 2017 by blkchr91

[GeneralDisorder]

That is not a valid test and you risk damaging hoses and plastic cooling system components doing things like that. The radiator cap on the turbo cars is 16 psi and that means it will purposefully vent at 16 psi into the overflow bottle. The reason your gauge says "Caution - 30 psi systems only!" is because it could explode in your face leaving you scarred for life if you don't end up blind. Ever heard of a pressure cooker explosion? That's what you are headed for here. DO NOT block the cooling system like that. YOU COULD DIE. Clear enough for you?

 

As to the venting of bubbles - drive it for a few days. If it doesn't stop this behavior then you want to have someone with an exhaust gas analyzer check for HC's emanating from the overflow bottle. Also a ring of oily residue usually indicates combustion byproducts are entering the cooling system.

 

Upper radiator hose failures are common on the turbo models as well as upper water tank to turbo outlet hoses, and radiator plastic tank failures. Highly reccomend an aluminium radiator if you don't have one.

 

GD

Edited September 13, 2017 by GeneralDisorder

[blkchr91]

That is not a valid test and you risk damaging hoses and plastic cooling system components doing things like that. The radiator cap on the turbo cars is 16 psi and that means it will purposefully vent at 16 psi into the overflow bottle. The reason your gauge says "Caution - 30 psi systems only!" is because it could explode in your face leaving you scarred for life if you don't end up blind. Ever heard of a pressure cooker explosion? That's what you are headed for here. DO NOT block the cooling system like that. YOU COULD DIE. Clear enough for you?

 

As to the venting of bubbles - drive it for a few days. If it doesn't stop this behavior then you want to have someone with an exhaust gas analyzer check for HC's emanating from the overflow bottle. Also a ring of oily residue usually indicates combustion byproducts are entering the cooling system.

 

Upper radiator hose failures are common on the turbo models as well as upper water tank to turbo outlet hoses, and radiator plastic tank failures. Highly reccomend an aluminium radiator if you don't have one.

 

GD

 

 

I appreciate the safety warning and thank you for your concerns. I won't *EVER* let things climb to this pressure again since I don't want to get hurt real bad. 

 

However, I'd like to know more about *WHY* this is not a valid test. I realize that the cap vents anything over 16 psi to the overflow. In this case, won't my overflow would be constantly filling up at idle to the point that it would overfill in no time even at idle?

 

The mitivac folks say it's time to throw your hands up and die if the system's pressure is over spec.

 

See link below.

 

 

Thanks for your help.

Edited September 13, 2017 by blkchr91

[golucky66]

One of the reasons that's not a valid test is because as the engine warms up, the coolant is going to as well. Thus expanding until the cooling system reaches engine temperature.

 

So if you say put your tester on there cold,then let the engine warm up with it on there. The pressure is natually going to increase because the coolant expands.

The difference, is when it should normally purge out extra pressure to the overflow, it can. Thus just increasing in pressure until something blows, or the coolant reaches operating temperature.

[kamesama980]

I assume the tester replaces the radiator cap? It isn't a valid test because you're blocking the pressure release point and simply having the system be capable of generating that much pressure ins't valid for reasons mentioned above (thermal expansion of the coolant).

 

I wouldn't get too hung up on the continued stream of bubbles without a gas analyzer. it's not uncommon for hot spots to boil or for the pump to cavitate, both of which are much easier without pressure in the system (Remember that the upper radiator hose temp is AVERAGE of all the coolant coming out of the engine. The part of the water jacket closest to the crank might be barely above the inlet temp while around the head it'll be MUCH higher. Lets say the outlet temp is 200f. there's a lot of water around the cylinders that's 180f and a little around the exhaust ports in the head and turbo water jacket at 250. That's why you need coolant to have additives and pressure to raise the boiling point to 280+ rather than just pure water boiling at 212 when the system average is 200. Now if you got a hold of a coolant exhaust gas tester and the bubbles tested positive as being exhaust gas, then yes I'd worry about a BHG. If you had the standard 16psi radiator cap and the overflow tank had bubbles blowing in it, then yes I'd suggest BHG.

[idosubaru]

I think this question/discussion comes down to:  nominally how much fluid moves between radiator and overflow tank on a daily basis in Subaru's?  

 

If there is fluid transfer with every drive cycle - then you're essentially closing a system that isn't designed to be permanently closed. 

The cap is intended to move fluid and the overflow tank isn't sealed to allow that fluid in (and corresponding volume of air to move out)- but you're sealing and preventing that. 

 

So basically you're suggesting the overflow tank and radiator cap can be removed - because that's what this test does.

 

The only systems I know of that operate close to that are thermo-siphon diesels that don't have water pumps...although they still have a cap, but theoretically you could get away without one on those. 

 

Now - if the overflow tank is only for long term changes - environmental or others - then maybe the answer differs. 

[idosubaru]

I assume the tester replaces the radiator cap?.

I think the description suggests it was on the overflow tank.

 

Another option is to try this test on another similar Subaru set up and see what results you get.  have any friends with a subaru that will let you play with their cooling system!?

[blkchr91]

One of the reasons that's not a valid test is because as the engine warms up, the coolant is going to as well. Thus expanding until the cooling system reaches engine temperature.

 

So if you say put your tester on there cold,then let the engine warm up with it on there. The pressure is natually going to increase because the coolant expands.

The difference, is when it should normally purge out extra pressure to the overflow, it can. Thus just increasing in pressure until something blows, or the coolant reaches operating temperature.

 

Wow, thanks. So it stops expanding once it reaches operating temperature. Any idea why that is?

[blkchr91]

I assume the tester replaces the radiator cap? It isn't a valid test because you're blocking the pressure release point and simply having the system be capable of generating that much pressure ins't valid for reasons mentioned above (thermal expansion of the coolant).

 

I wouldn't get too hung up on the continued stream of bubbles without a gas analyzer. it's not uncommon for hot spots to boil or for the pump to cavitate, both of which are much easier without pressure in the system (Remember that the upper radiator hose temp is AVERAGE of all the coolant coming out of the engine. The part of the water jacket closest to the crank might be barely above the inlet temp while around the head it'll be MUCH higher. Lets say the outlet temp is 200f. there's a lot of water around the cylinders that's 180f and a little around the exhaust ports in the head and turbo water jacket at 250. That's why you need coolant to have additives and pressure to raise the boiling point to 280+ rather than just pure water boiling at 212 when the system average is 200. Now if you got a hold of a coolant exhaust gas tester and the bubbles tested positive as being exhaust gas, then yes I'd worry about a BHG. If you had the standard 16psi radiator cap and the overflow tank had bubbles blowing in it, then yes I'd suggest BHG.

 

It does replace the radiator cap. The radiator is filled by a separate tank on the 03-05 Forester XT. Great info. Reading and re-reading. Thanks.

[golucky66]

Wow, thanks. So it stops expanding once it reaches operating temperature. Any idea why that is?

Fluids expand and contract when exposed to heat or cold, it's just science there.

 

So at 70 degrees F, the cooling system has 0psi (not including normal atmospheric pressure)

And as the coolant heats up, it also expands. The system is (in theory) completely sealed. So as the coolant heats up, it expands, which generates pressure because there no extra room for this expanded coolant.

It expands up to operating temperature 185-195 degrees F. And once its at that operating temperature, it doesn't expand anymore because it's not getting any hotter. Just hovering at operating temperature.

 

The radiator caps open up at 16psi(?) and keeps the cooling system at a constant 16 psi.

 

So say the cooling system gets to 16 psi under normal situations at 130 degrees F. Mow by removing the radiator cap, and completely dealing the system. You have another 50-60 degrees of coolant expansion until it stabilizes.

Same volume (calling system size) higher temperature. Pressure HAS to go up.

[blkchr91]

I think the description suggests it was on the overflow tank.

 

Another option is to try this test on another similar Subaru set up and see what results you get.  have any friends with a subaru that will let you play with their cooling system!?

 

Thanks for your posts. This doesn't replace the overflow tank. On the 03-05 FXT there is a separate filler tank. The pressure tester replaces the radiator cap on that filler tank.. I had to look in the FSM to even come up with a name here....which turned out to be "radiator filler tank" as opposed to "overflow tank". Wish that I had some buddies with a similar vehicle. The truth is I have only seen one of these in person in the past 8 years. Not just because it is rather an uncommon vehicle but mostly due to demographics here.

Edited September 13, 2017 by blkchr91

[blkchr91]

Fluids expand and contract when exposed to heat or cold, it's just science there.

 

So at 70 degrees F, the cooling system has 0psi (not including normal atmospheric pressure)

And as the coolant heats up, it also expands. The system is (in theory) completely sealed. So as the coolant heats up, it expands, which generates pressure because there no extra room for this expanded coolant.

It expands up to operating temperature 185-195 degrees F. And once its at that operating temperature, it doesn't expand anymore because it's not getting any hotter. Just hovering at operating temperature.

 

The radiator caps open up at 16psi(?) and keeps the cooling system at a constant 16 psi.

 

So say the cooling system gets to 16 psi under normal situations at 130 degrees F. Mow by removing the radiator cap, and completely dealing the system. You have another 50-60 degrees of coolant expansion until it stabilizes.

Same volume (calling system size) higher temperature. Pressure HAS to go up.

 

My head hurts, but I asked for it.  Thanks for taking the time to explain this. I knew that pressure had to go up, but didn't understand the rest. I'll read and re-read.

 

I'd generally sit back and take short road trips to see how the "cycle" is going, but unfortunately I have to make the same road trip again very soon. Crossing fingers and thanks for all of the help.

[golucky66]

I probably could've explained that better. But this is why I'm a technician not a service writer. Lol.

[blkchr91]

I probably could've explained that better. But this is why I'm a technician not a service writer. Lol.

 

Nah, you did just fine. I have difficulty learning, but you wrote it well so after a few reads it became super clear actually. Thanks again.

[ThosL]

i'm sorry to hear of your problem and hope it isn't a bad head gasket.  Thankfully my 97 2.5 engine is running well; I bought the recommended leak fix with a minor issue.  HG jobs are quite expensive so hope you don't need it.

[blkchr91]

i'm sorry to hear of your problem and hope it isn't a bad head gasket.  Thankfully my 97 2.5 engine is running well; I bought the recommended leak fix with a minor issue.  HG jobs are quite expensive so hope you don't need it.

 

Thanks for your empathy. I hope that I am ok. I'll report back and let you all know if it made the 400 mile trip and if so how it made the trip.

Edited September 13, 2017 by blkchr91

[ThosL]

I have tried all of the stop leak products, email me if you want my experience.

[blkchr91]

I have tried all of the stop leak products, email me if you want my experience.

 

Sure, but based on what I am seeing here I think that would be a bit early to assume that I have a bad head gasket right?

[blkchr91]

Drove it 400 miles without incident. Thanks so far.

[golucky66]

Drove it 400 miles without incident. Thanks so far.

My dads 06 Baja intermittently for about 3k miles would overheat when coming to a stop after driving for a while.

It'd blow coolant all over the ground (because the temp went up too much) never got it red hot. But it turned out to be a HG.

 

Hopefully yours is a fluke or something simple. But. Typically not

[blkchr91]

My dads 06 Baja intermittently for about 3k miles would overheat when coming to a stop after driving for a while.

It'd blow coolant all over the ground (because the temp went up too much) never got it red hot. But it turned out to be a HG.

 

Hopefully yours is a fluke or something simple. But. Typically not

 

Well this thing has never overheated. I hope it stays that way. Thought the same thing about my Tribeca. 6 months later and it sure has revealed itself. The system is still pulling vacuum from the overflow which is a good sign. I'll have to watch it. Haven't checked the overflow to see if it is blowing coolant.

Edited September 14, 2017 by blkchr91