Overheating, what makes a Subaru a Subaru!

[Trav]

Only the open-deck EJ25D/251/253 experience this type of failure; where the cylinders & deck surface are not connected. From what I understand, there were multiple issues (bad grounds exacerbate the issue) that sometimes combined, but the root of the issue was the single-layer coated gasket that failed as the cylinder & deck expanded at different rates, and the cylinders basically rub the coating off from this action until they leak. Supposedly, the closed-deck EJ255/257 nor aftermarket conversions to closed decks suffer the same fate, but most of them also got an MLS gasket instead of the single-layer that was originally used.

Maybe somebody smart like Trav can confirm, since like I said none of mine have actually failed.

Spot on! The open deck engine were a real POS, the closed decks were great and had 200K and more in them easy if they were maintained and like all Suby engines the grounds were taken care of.
Even the open deck engines were okay if instead of just changing the HG the case was split and the bores honed with a deck plate (hot honing is even better if you can find someone to do it), the cases decked and the heads planed and using a MLS HG. They will last a long time.
Again with these engines it is grounds, grounds and grounds, these fail and coolant electrolysis really buggers the engine.

An older article but still relevant today.

https://www.sae.org/publications/technical-papers/content/2002-01-3299/

 

[SubieRubyRoo]

Spot on! The open deck engine were a real POS, the closed decks were great and had 200K and more in them easy if they were maintained and like all Suby engines the grounds were taken care of.

Again with these engines it is grounds, grounds and grounds, these fail and coolant electrolysis really buggers the engine.

Exactly. Like we’ve both said the factory grounds are not sufficient even brand new; I forget the company I went with but their ground kits go from both strut towers, across the top to the TB and alternator case, and on the bottom side from the frame to each head.

“They” say it will result in a smoother idle; that’s so subjective so I won’t comment on that. But the engine definitely cranks better and like I said I’ve never lost a head gasket on the several EJ25s I’ve owned.

And yes, @Slow Car Sport Mode, the EZs never had issues because they are all closed decks. In reality, looking at the closed decks and chain driven cams, the flat-6s were really the pinnacle of Subaru’s engine design.

 

[slacktide_bitog]

Another update, still no problems

The head gasket sealer is still working

 

[dumkid]

I always thought it was normal for coolant to start rising once you started the engine (like if it's in the radiator neck it'll rise an inch or so if the engine is ran for a minute)

 

[slacktide_bitog]

Overheating again after replacing timing belt and water pump. The TB had very light cracking, and the WP pulley made noise when I spun it manually.

Anyway, I thought I bled the coolant right after replacing the TB/WP, but either there is still air in the system, or the head gasket blew again.

That would make it 3 years on the head gasket sealer.

But since I only used half the bottle per the instructions, I could always try again with the other half of the bottle.

Perhaps the bad water pump made it overheat so bad it ruined even the head gasket sealer. Even if the HG is bad again, the water pump did still need to be replaced.

175k on the car

 

[thetricky]

At that mileage I’d almost give it a simple rebuild, if you want to keep it of course. Went through the headmaster fiasco with my 2001 RS, EJ251.

 

[slacktide_bitog]

I added the rest of the head gasket sealer and let it warm up and just shut it off.

Possibly, one head gasket blew 3 years ago, and the other one just blew now

I always thought it was normal for coolant to start rising once you started the engine (like if it's in the radiator neck it'll rise an inch or so if the engine is ran for a minute)

Yeah, it's normal for coolant to rise a little, but it's NOT normal for it to rise enough where it's pouring out

 

[ClutchDisc]

Change out the head gaskets for the MLS turbo head gaskets. A fix in a bottle is only going to go for so long.

 

[slacktide_bitog]

Change out the head gaskets for the MLS turbo head gaskets. A fix in a bottle is only going to go for so long.

The job is impossible on these cars, so if it comes to that, I'll just drive the car to the junkyard and get a Toyota

 

[ClutchDisc]

Its not impossible, plenty of people have done it. I know of someone who replaced the head gaskets on their Subaru in their apartment parking lot…

 

[Oliveoil2]

Might be time for new jugs and pistons? If not just do head gaskets and live to fight another day. This Subaru is working you to death.

 

[slacktide_bitog]

UPDATE

Car isn't overheating anymore, but coolant still bubbles when trying to bleed. Also, the coolant doesn't return to the radiator after cooling down. The coolant level goes up in the expansion tank/overflow bottle when warmed up, but the coolant doesn't go back down after cooling down overnight.

I might buy either more Bars Leaks, or I might try K-Seal since it costs less.

 

[Ranger83]

The job is impossible on these cars, so if it comes to that, I'll just drive the car to the junkyard and get a Toyota

“Toyota, where driving fun goes to die.”

We have two 3.0R’s.

 

[4wd]

“Toyota, where driving fun goes to die.”

We have two 3.0R’s.

Here it’s what illegals drive like they drove back home …

 

[slacktide_bitog]

It's building pressure but doesn't release it

Also, the cap on the coolant bottle popped off, so I had to order both that cap and a radiator cap, both from the dealer. Unfortunately, the cap took that little hose from the top with it, so I need a new hose too, but they don't make it anymore

The part number for that hose is 45161TA680

With no cap and no way to contain the pressure, it sprayed coolant all over the engine! Under the hood is all green

 

[zzyzzx]

Its not impossible, plenty of people have done it. I know of someone who replaced the head gaskets on their Subaru in their apartment parking lot…

I'm pretty sure there is a YouTube video where someone changes a Subaru head gasket in an auto parts store parking lot.

 

[slacktide_bitog]

I installed the OE Subaru cap, and I noticed it fits tighter to the radiator neck than the aftermarket Sankei cap. I'm still on the original radiator.

 

[slacktide_bitog]

It's foaming now! I see the coolant foaming in the coolant overflow bottle! The coolant in the reservoir still bubbles, and now there is foam.

The coolant doesn't seem to be mixing with the oil, and the oil still looks normal.

 

[CleanSump]

It's a head gasket leak between a combustion chamber and the cooling jacket. Maybe it's time to accept you need a new gasket and maybe a trip to the machine shop if the head isn't flat.

 

[slacktide_bitog]

It's a head gasket leak between a combustion chamber and the cooling jacket. Maybe it's time to accept you need a new gasket and maybe a trip to the machine shop if the head isn't flat.

Yeah, not worth it. If the car can last another month without any more problems than it already has, then I'll be happy.

The head gasket set alone is $200, plus the cost of machining, the time to drop the engine, no way! The cost of all that is enough to buy a real car with a real engine