Burp cooling system after using Block Tester??

[sparklehorse]

Hello,

I‘m getting ready to sell my 2010 Forester to a friend. It only has 65,000 miles on it, so a blown head gasket isn’t likely, but I told my friend I would use a Block Tester kit to confirm there‘s not currently an issue with the head gaskets. Trouble is, you have to remove quite a bit of coolant from the radiator neck to do this test. Instructions say to draw down the coolant with a turkey baster until the coolant level is 2 to 3 inches below the neck. This is to prevent actual coolant from being drawn into the testing fluid and contaminating it. I’ve never done this test before and I‘m worried about leaving the system with a big air bubble in it when I’m done. Is that a valid concern? Would I need to burp the cooling system after performing this test? Or is it fine to just replace the removed coolant by pouring fresh coolant into the radiator neck? The system currently has the blue Subaru Super Coolant in it, and I do have a gallon of fresh Super Blue on hand. 
Thanks so much for any and all help!!
Gordon

[1 Lucky Texan]

sounds like the car is symptom free so, I wouldn't bother with the test.

[sparklehorse]

6 hours ago, 1 Lucky Texan said:

sounds like the car is symptom free so, I wouldn't bother with the test.

I bother because it’s an EJ253, the last of the problem engines, and the 2010 Forester still had the the problem gaskets. And I had a gasket fail on my last Forester, a 1999, at only about 70,000 miles. So call me paranoid, but I would not feel good about selling this car to a friend without being certain of its gasket health. He’s aware he will quite likely face this issue eventually, but hopes to get at least a few good years out of it before that happens. I hope he does.

[lmdew]

1+ Lucky TX had to say.  He's aware of the future maintenance that may be needed.  Testing is not %100 either way.  I'm sure you're passing along the Subaru at a fair price to a friend so be happy you have a new Subaru owner in the gang.

[sparklehorse]

So I emailed the company that makes the Block Tester and here is what they have to say about this:

>>Hi Gordon, lowering the coolant level in the radiator should not cause an air pocket to form in the cooling system.  The only time air would be introduced is if the level is brought down so low, the water pump draws air and sends that into the engine.

That said, I’d still recommend burping the system after bringing the coolant level back up to normal.  It’s very easy to do, and will provide peace of mind that there isn’t an air pocket in the cooling system, which can lead to interrupted coolant flow and localized overheating.  Usually, there’s a bleed screw that you open while the engine is idling, and you close it when only coolant and no air bubbles are coming out.

Good luck, and I hope your Block Tester brings you good news!

Regards,

Tom<<

 

I bolded the relevant text for emphasis. Interesting there is no mention of this in the instructions. Now I have to figure out where this bleed screw is (I'm not a mechanic).

.

[idosubaru]

On 2/23/2020 at 1:25 AM, sparklehorse said:

I bother because it’s an EJ253, the last of the problem engines, and the 2010 Forester still had the the problem gaskets. 

Nah, air bubble isn't a concern.  You won't remove enough coolant to worry about. remove coolant, keep the nose of the car higher than the rear, and top it off when you're done.  drive it and check the coolant level and top it off again as needed.  watch the temp gauge carefully on the first drive.  if it wavers or rises, it has air.  but all of this is rather overstated, it's not a big deal. 

But it's a waste of time.  That engine will never fail that test if you don't currently have any symptoms because of their well known failure mode.  you have more risk of screwing something up than that test telling you anything meaningful. 

Also if you truly are worried and wanted to test for hydrocarbons in the exhaust, use a gas analyzer, not those kits.  those chemical kits routinely give false negatives, which is 100% the only possible result on your asymptomatic EJ253.  The false-negative chemical tests and positive gas anazlyer scenarios happen when testing without symptoms and/or very early headgasket failure signs, which is the territory you'd be in with no symptoms.  So you're using a failure prone test in the exact scenario where it's prone to not work. 

if it doesn't have a new timing belt and pulleys then it has far larger statistically relevant mechanical issue than the self fulfilling prophecy of a negative test result for that EJ253 asymptomatic headgasket.  i wouldn't sell that car without a complete timing belt kit installed.  i've bought and sold many dozens of Subarus and many EJ25s, that, i would feel bad about.  those components are a decade old and it's an interference engine which means larger repair expense than headgaskets if the timing pulleys seize.  it's usually the lower cogged idler on that engine, but replace them all while you're in there.  at a bare minimum i'll replace just that cogged idler and install a new Subaru belt, but that's usually on older rusty cars which likely isn't yours.

[idosubaru]

36 minutes ago, sparklehorse said:

 

I bolded the relevant text for emphasis. Interesting there is no mention of this in the instructions. Now I have to figure out where this bleed screw is (I'm not a mechanic).

Usually it's on the lower passengers side of the radiator, inside the engine bay.   I wouldn't touch it though.

[forester2002s]

1 hour ago, idosubaru said:

Usually it's on the lower passengers side of the radiator, inside the engine bay.   I wouldn't touch it though.

Isn't that the drain valve for the radiator?

I would expect that a bleed (for air) screw to be on top of the radiator, but this might be manufacturer-dependent.

[idosubaru]

13 minutes ago, forester2002s said:

Isn't that the drain valve for the radiator?

I would expect that a bleed (for air) screw to be on top of the radiator, but this might be manufacturer-dependent.

Oh yeah I thought you meant drain. bleed screws are on top, usually passengers side, if equipped.  Not all subarus have them.  

[sparklehorse]

Thanks for your reply. So the EJ253 was apparently the last of the four engines known to be prone to head gasket failure. Last week MrSubaru1387 posted a detailed video to his YouTube channel explaining the whole history. See below. For the 2011 Forester model year, Subaru finally switched to the MLS gaskets on the EJ253 which solved the problem. My 2010 Forester however still has the old, 'prone to failure' gaskets. The only thing as far as I can tell that sets the 2010 apart from it's earlier kin folk is that they had started adding conditioner to the coolant by then. How much that helps I don't know, but I know there are people with 2010's that have had the HG failure, but at double my mileage. Now all of this comes from the interwebs, so you can't know with 100% certainty what is true and what is not, but I've spent a lot of time researching this issue and that's the clearest picture I've been able to piece together. I'm all ears if you're privy to info I haven't seen and am more than willing to listen to what anyone has to say on this topic. Subaru doesn't say much so it's hard to get at actual facts. Like I said earlier, I had a 1999 whose gaskets failed at an early age, so call me paranoid but that's where I'm coming from.

https://www.youtube.com/watch?v=-aq0hDvKJ5Q&amp;t=870s

Thanks for reading!

.

 

[1 Lucky Texan]

conditioner does ZERO for internal HG leaks. It will ameliorate/stop external weeping, pinhole leaks in rad. and some hose leaks.

If you have no; 'blowing-out' the overflow, heater going cold, bubbles in the radiator/overflow or wavering/odd temp gauge behaviors - the block test is a complete waste of time/money. The block test works best to distinguish combustion gasses from 'steam'. If there is no stream of bubbles, there's no reason to try it.

 

Edited February 25, 2020 by 1 Lucky Texan

[idosubaru]

15 hours ago, sparklehorse said:

Thanks for your reply. So the EJ253 was apparently the last of the four engines known to be prone to head gasket failure....

.

 

Right, all of that is very well known and nothing we need to rehash here. That has nothing to do with the points posted here.  Reread my posts here, that has everything you need for your current questions. 

If mr Subaru-monetizing-YouTube guy didn’t say any of that, then it’s unhelpful to you’re current question or he doesn’t know.

i totally get your concerns, they’re warranted to an extent, but not blindly in a vaccuum.  EJ25 failure modes are specific to each variant and well known in how they occur and how to address them.  what I’ve already written earlier is specific to your engine and situation.  Chemical testing is pointless.  

The coolant conditioner only helps with external leaks, not internal leaks. all that’s needed is to look for external leaks at the mating surfaces.  It’s either leaking or it’s not.  In my experience the 2010s seem to more often have internal leaks.  In which case, like has already been said, Chemical testing is pointless. 

Nothing is needed, but if you want to test, a gas analyzer is the only trust worthy test for asymptomatic EJ25 head gasket testing.   

[nvu]

 

19 hours ago, sparklehorse said:

My 2010 Forester however still has the old, 'prone to failure' gaskets.

 When will it fail? Maybe next month, next year, maybe never.  If your conscience making you go through this, why not offer something like $200 towards repair if it fails within a year?

[CNY_Dave]

I try to always fill with he front end raised.

I have a hilly yard so sometimes I fill then park it on the lawn with the nose up.