Subaru OEM Coolant Conditioner

[golucky66]

Hey everyone,

 

I recently had a 09' OBW 2.5 SOHC in my shop that finally (after 225k miles on original HG) blew them to the point where coolant was pouring out of the car. 

 

A quick background on this car, the customer bought the car brand new from the dealer and immediately brought it to my shop (as we've worked on his cars for a long time) and as per warranty, we added coolant condition (the subaru OEM one) at the 30k service interval when we changed coolant. We did this in order to ensure there would be no doubt his engine would be under warranty. 

We again did a coolant flush and conditioner at 60k and then another at 90k as per service recommendations (this customer likes to stay on top of maintenance and take car of his car)

 

Not soon afterwards, his heater core was completely clogged, to the point where you couldn't even blow through it. Luckily, he was under the BG protection plan and they covered all the charges for us to install the new heater core. Not to mention the radiator that had a lack of flow (original radiator) around 80k which BG also covered (thank god for the customer)

 

Flash forward 110k miles to 225k on the clock after the OEM conditioner was used 3 times (my shop stopped using it after the heater core failed because we were done with that BS)

 

Car comes in after finally blowing HGs. 

I remove the heads to see obvious locations where coolant was blowing by the gasket. But also, when I removed the heads there were hard thin layers of what literally felt and looked like a potato chip (except it was white) It was ALL over the coolant ports on the block and head. I spent probably a good 30-45 minutes removing as much as I could, the parts that were stuck to the block I could scrap up with a pocket screwdriver but it certainly wasn't easy. 

The only reason I actually did this was because every one of the ports on the block and heads were restricted by probably, 20% due to the condition (which has a very nontraditional type of stop leak in it)

 

So, cleaned all of that up, reinstalled heads with new gaskets. And, well I still had an over heating issue.

 

Long story short(ish) 

 

The heater core was partially restricted when it came into the shop for the HG job (and I didn't catch it because it still flowed plenty of water through it when I put a garden hose up to it, but the second you blew into it and compared it to a new core, it was like blowing through a 1/4" straw verse a 1" straw.

What was happening was because of where the port for the heater core is (on the side of the water pump, right behind the thermostat) when the heater core wasn't allowing enough coolant through it as the water pump needed, the water pump started frothing the coolant at the pump, and because the heater core is the highest spot on this system, the air bubbles would slowly work their way up to the core, combine with other little bubbles from the frothing and then turn into huge air pockets.

Once there were these huge air pockets in the core, they would occasionally get sucked down to the water pump and slam the t-stat closed (because steam can not open a t-stat, only liquid) 

Replaced the heater core, after the HG were initially replaced and car runs perfect now.

 

TL;DR

Be very, very cautious when using ANY stop leak/conditioner with stop leak in it. Even the OEM specific one. 

I'm not saying it couldn't prolong your HG failure, but if using it on a regular basic or IMO more then once, you're asking for trouble with your radiator and heater core. 

 

I can post pictures of a fraction of the debris I removed from the block sometime in the near future.

[1 Lucky Texan]

interesting - no chance the owner used any type of leak-fix? or had a different shop do so?

 

you might contact SoA, if there's every indication their products were used per their instructions, maybe there's a chance for some 'good will' with a refund or other assistance.

 

kinda want some lab to analyze the stuff you found to see if it ALL is from the soob product.

 

 

 

this may be the first time I've read of a problem with the soob conditioner. a LOT of cars have had this put in them.

[golucky66]

Agreed that a lot of people use the conditioner.

 

I can't give you a 100% definite answer because well, frankly, people lie. But this customer has been with us probably 10ish years, doesn't do any work himself, we see him every 3.6k miles for an oil changes and do every little job and every big job he needs.

So I doubt he did add anything. 

Plus... why would someone add a stop leak to their cars system when their HG isn't even seeping oil yet (pre 100k miles on his car) which wouldn't explain why not only did his header core clog around 90k and the radiator at around 80k... Which led us to believe that it was the conditioner we used, especially apparently according to my manager (who's been there for 12 years) when his heater core clogged at 90k, it was like 200 miles after we put the conditioner in with the coolant flush...

 

I would LOVE some lab results or something because this is a really weird thing and I worry a little about everyone else out there who swears by that stuff.  

[DaveT]

Yes this is pretty odd. I've never used stop leak, and have never seen a heater core clogged. Even my 87 is still fine. I had one engine that was leaking coolant and I kept it going by just adding water all the time, and it built up a little coating of minerals from the water, but nothing like that.

[1 Lucky Texan]

it is true that there have been a few threads lately that seem to have clogged heater cores.

 

kinda wonder if an overheat/boil-over event can cause the SCC to begin depositing where it shouldn't?

[DaveT]

Interesting though, re: overheat / boil over.

[Rooster2]

With multiple heater core plug ups, and radiator plug up, plus the "potato chip" type deposits, it just seems like too much stop leak some how was put in the system. Doesn't sound like your shop put in too much, but am suspicious someone else added more stop leak product that you are not aware of. If so, who knows what was added, and how much, or how compatible with Subaru conditioner.

[Fairtax4me]

Once there were these huge air pockets in the core, they would occasionally get sucked down to the water pump and slam the t-stat closed (because steam can not open a t-stat, only liquid)

This doesn't happen with Subaru thermostats. Cheapo aftermarket stats, yes, but not Subaru thermostats. The wax chamber on Subaru thermostat is huge specifically to prevent the thermostat from closing rapidly. Stick one in a pot of boiling water until it opens then remove it and set it out in open air and compare it's action to a Cheapo.

 

Since the thermostat is on the inlet side of the water pump, it's bathed in cold coolant all the time (cold being a relative term) The coolant route through the heater core is designed to bring hot coolant back around to the back side of the thermostat which helps keep it open.

If the heater core or its hoses are clogged (including the steel lines that run to the crossover tube and to the water pump) and the flow is blocked, it won't move enough hot coolant back around to the thermostat to keep it open. The colder coolant coming in from the radiator will cause it to close.

[golucky66]

Then explain to me when this partially restricted core was causing it to over heat. Because we put in a new core and didn't see temperatures' anywhere near 205 degrees except under full load.

Were as before 205 was low.

We had the OEM t-stat in there because we didn't want to take any chances with any aftermarket because we've ran into issues before.

Nothing was blocked except the heater core. I cleaned the crossover pipe due to all the gunk in there and flowed tons of water through there. And also checked both the heater core hoses.

The heater core caused the over heating, and it was making It's own air pockets because both times after I filled the core up first with coolant to prevent air pockets, the system still go air in the core. Both times I removed the hoses after I had the temperature around 238 degrees, the core had about 4 Oz of coolant in it.

 

Now, with the new core, I do not have that issue.

[1 Lucky Texan]

^^ interesting, but I kinda have a feeling the car is a ticking time bomb.

 

not saying the core wasn't clogged, but I just feel the car got into a cycle of slight overheat which started/increased a HG leak, which introduced a 'gas' bubble, rinse-repeat.

 

or intermittent rad fan operation leading to boilover/local steam bubbles ????

 

or maybe someone splashed in some Dex ('death' cool lol!) look at some images, seems like it could leave some toasted potato chip debris.

 

anyway, kinda feel like the heater core was more a result of issues, which later caused it to contribute to the problem. There's only 2-3-4 ways 'gas' (as opposed to the more narrow description 'air') can get into the system.

 

I dunno - seems like once or twice a year I read of some new way Subaru cooling systems fail.

 

take care of your cooling systems people!

Edited September 18, 2016 by 1 Lucky Texan

[golucky66]

Fans were working.

But oh well. It's fixed now!

 

Agreed! Take care of your cooling system!

[Fairtax4me]

Then explain to me when this partially restricted core was causing it to over hea

I explained that. Read it again.

[golucky66]

Touche, makes sense.