Pushing a little coolant around....still diagnosing

[KZJonny]

I think I know where this is leading, and it will mean a pile more work for me if I am correct, but we will see.

 

A while ago, I noted that occasionally I would have a little coolant spilling over the reservoir in hot weather, or after a particularly aggressive back road session. I wasn't much, an initially I had definitely overfilled my coolant system when doing my first round of mods and cleanup last summer.

The obvious culprit would be an internal leak at the headgaskets, and a hydrocarbon test kit on the way to confirm. Going to pick up a new rad cap on the way home to rule that out if possible if Subaru has one in stock, which..... who knows, maybe.

For the moment, it is just an inconvience as my coolant temps are great and actually generally better since installing a skid plate again. And it only *seems* to happen when I'm really stepping into the throttle.

 

So, since Accesstuner is no longer a thing, I can't just reduce target boots etc... and see if that eliminates the problem. My OTC Stage 2 tune allows for a little over 16psi, which I was generally under the impression was safe for the OE head bolts, but I know that time and heat cycling matter even for an engine that really isn't very high miles. (160k kms just a while ago.) I'm going on the theory at the moment that I am getting a little bit of head lift at higher boost/rpms.

Assuming this is the case, the only solution would be to upgrade to the 11mm ARP studs, yes? Further assuming I decide to go that route, instead of just trying to stay below 15psi etc.... what else would be smart to have a look at, ya know..... while I'm in there. I figure any gaskets I haven't already changed, same for vacuum hoses and maybe a bling new set of fuel hard lines, just because it will be easy at that point. Professional hot tanking and flattening of the heads is a given if I am tearing things apart. I would do any further replacement of seals and the like on the heads myself to keep costs reasonable. All that is worst case situation, but I'd rather be mentally prepared for it.

 

I'll come back around when I can confirm or deny hydrocarbons in the coolant, and ideally see if they are not present when driven out of boost, but become present while hooning on it a little.

Edited August 11, 2023 by KZJonny

[KZJonny]

Damnit. Coolant test shows low levels of hydrocarbons.

Guess I’ll have to get the spare heads out and start cleaning them up and order some gaskets.

I’ll keep an eye on consumption and coolant temps in the meantime….

[KZJonny]

Hmmmm.

Maybe part of the problem?

Edited August 14, 2023 by KZJonny

[KZJonny]

Aaaand conveniently it’s the same part as the rad cap from an NA 2.5L

Thank you Outback!!!

[KZJonny]

Well, two days of mixed driving, and not a drop of coolant moving. So there is that.

I suspect that at max boost, if I go a legit flogging session, it may be a problem again, but I will see what a tune with a 3-port has to say about that. I might well be overboosting in places where I really ought not to be, but....

I think the plan will be to drive semi-conservatively for the rest of this season and do all the rest of the fixes/improvements needed over the winter. Spring time will get a fresh tune and see where that gets me.

 

Meantime, the OB needs a new rad cap now, and brakes, and exhaust and repair to the rear jack point..... and and and...

[Max Capacity]

Did you replace both radiator caps ? I did a few years back and that stopped the wagon from pushing coolant into the bottle. Well, it allowed the system to suck coolant back into the radiator. I had to get a cap from Mishimoto for the big radiator and a cap from NAPA for the turbo tank.

 

The wagon has ARP head studs.

[KZJonny]

1 minute ago, Max Capacity said:

Did you replace both radiator caps ? I did a few years back and that stopped the wagon from pushing coolant into the bottle. Well, it allowed the system to suck coolant back into the radiator. I had to get a cap from Mishimoto for the big radiator and a cap from NAPA for the turbo tank.

Stopped at Subaru this morning on the way to work for a pair of new caps. This is something I want OE parts for.

The Rad cap itself looked ‘okay’ but the turbo reservoir was totally done, as the photo shows.

Figured for the money, I’d just do both. They are probably original an 18 yo at this point.

Subaru parts guys know me now, and are giving me a 15% “old Subaru” discount on everything, which is nice.

[Max Capacity]

Great to hear they are taking care of a good customer. My guy's take care of me too. They were very helpful when I told the sales person that they knew me well, when we were buying the 16' Outback.