Overheating, what makes a Subaru a Subaru! But hopefully it's just the radiator cap

[Sayjac]

If Toyota pink, which uses sebacate as the organic acid wasn’t as “aggressive” as 2-EHA, millions of 1MZ/3MZ/2GR V6s and the UR-series V8s wouldn’t leak coolant from the valley plate or the timing cover/water pump junction.

So you're saying have 'definitive proof', i.e. scientific studies backing the statement that sebacate used in Toyota SLL pink is "THE sole" cause of the issues you note? If so, please post links to those studies. I'd be interested in reading an authoritative "independent" study (or studies) proving that to be the case. In the past, I've seen SLL blamed for Toyota water pump weep hole leaks here too. That claim was debunked by another member here proving that not to be the case. As I don't currently own a Toyota, I don't use SLL. But, I'm sure others that do would be interested in seeing proof SLL pink is a problematic AF.

 

[2EHA]

^^^While some or rather one 'afaik' OEM Asian AF may use an inhibitor labeled as "plasticizer", zero OEM Asian Phoat AFs use 2eha as inhibitor in their formula.

hyundai

now go home

 

[2EHA]

. Ford learned the same lesson with the Dex-like Specialty Orange and heater core plugging. There's MANY better alternatives if you can't engineer things correctly!

heater core plugging is industry wide and has 0 to do with trapped air. phosphate is needed to protect new flux brazed cores.

 

[Sayjac]

hyundai....

If Hyun has switched to something now using 2eha then they are no longer using a "true Asian Phoat." AF Good for them, they must have engineered their cooling system for its use. Since outlier(s)now noted, Stellantis/Mopar OAT doesn't use 2eha in its formula either.

 

[2EHA]

Since outlier(s)now noted, Stellantis/Mopar OAT doesn't use 2eha in its formula either.

paraflu up has whatever it uses omitted from the SDS. it was used interchangeably by maserati with shell longlife, a known 2eha containing coolant.

stop chasing the boogeyman and realize that all standard OAT coolants are interchangeable and any coolant introduced in the last 25 years is miscible

 

[Sayjac]

^^^^When Mopar OAT came out, SAE Mobilus article (Chrysler switches to OAT for longer service interval) posted this subforum numerous times since intro 2013, says no 2eha. I'm going with that.

 

[slacktide_bitog]

another update

I used the Lisle coolant funnel to bleed any air that might be trapped in the system, and to try to purge any remaining exhaust/combustion gases left in there. Besides bubbles, occasionally it splashed coolant! It only got to 187F

Then I removed the funnel and put the radiator cap on. Temp got to 201F and the radiator itself gets hot now, but the cap is still cold!

Radiator cap is cold. Radiator itself is hot. Upper radiator hose is hot. Lower radiator hose is warm.

 

[Warstud]

I'm glad you found the problem and it wasn't the HG.

 

[slacktide_bitog]

I'm glad you found the problem and it wasn't the HG.

I'm still not ruling out that the HG was bad, just that the head gasket sealer is working so far

The head gasket probably was damaged since it did overheat. The coolant level went up with the cap off (rising in a way consistent with combustion getting past the gasket and pushing the coolant). It's possible that the cap didn't pressurize when needed, causing the coolant to boil/overheat and blow the HG

 

[dalai]

little off topic maybe.

I have done timing belt replacement (along with all pulleys, water pump, tensioners) on my forester 2011 with EJ25 DOHC turbo engine at 107k running.

I did accordingly with manual and Utube guys. And assembled back only to find out that it is now overheating when going for like 5km. When idling, it goes back to normal temp.
(Radiator was replaced a month ago.)

What could be the cause guys?

(I reused the coolant cuz its only a month old. But I spilled some and added 0.5L water instead, would concentrate of coolant degrade and cause this mild overheating?)

or any potential cause i can think off maybe overtightening new water pump? (really cant think of any other reason, help me pls)

at the moment, i can keep going at mild speed with heaters on with almost normal temp level.
Thanks for your reply

 

[Slow Car Sport Mode]

I'm still not ruling out that the HG was bad, just that the head gasket sealer is working so far

The head gasket probably was damaged since it did overheat. The coolant level went up with the cap off (rising in a way consistent with combustion getting past the gasket and pushing the coolant). It's possible that the cap didn't pressurize when needed, causing the coolant to boil/overheat and blow the HG

If you have an EJ251 it will blow anyway.

 

[slacktide_bitog]

6 months later, the head gasket sealer is still working

If you have an EJ251 it will blow anyway.

the EJ25D is even worse

At least the EJ251 head gasket fails externally
(the EJ25D fails internally)

 

[Slow Car Sport Mode]

6 months later, the head gasket sealer is still working




the EJ25D is even worse

At least the EJ251 head gasket fails externally
(the EJ25D fails internally)

Had a 1998 ? Or 1999 EJ25D. Returned to dealer and we got something else... it's lighter than a Gen2.. interior a little smaller, in my opinion...

The first gens are charming... 2nd gens are the best and go from there. The third gen sedan really is a looker, as are 2nd Gen SUS.

Let's either LS or 2JZ swap ours, then no more leaks. Single turbo 1000+hp, AWD delete by default....

6 months later, the head gasket sealer is still working

"Turbo" EJ255/257 head gaskets, sir... yes, sealers, but I've always been told that's not the proper method for that kind of thing. Even though Subaru said it was.

 

[SubieRubyRoo]

+1 to the bad news about head gaskets. Overheating increases the chance of them needing replacement. As you replenish the coolant, Subaru has a conditioner you can add. If the head gaskets are bad, the conditioner won't fix them, but it can't hurt and might postpone the inevitable.

Subaru coolant conditioner is required with every antifreeze replenishment; 2 years max for coolant. I swap the thermostat, o-ring, coolant, and SCC like a Swiss watch every 24 months.

I’ve personally never had a HG fail; I have had several that had a little oil seepage from the bottom of the head but it’s just a trickle & never amounts to more than 1/8” on the dipstick on a 6k OCI.

I’d personally only use a Subaru radiator cap but like you said a ‘98 is one of the high-risk years. Best of luck!

 

[dlundblad]

1998?

Too bad it hasn’t been on the market longer so you’d know it overheated and that it was a lemon.

 

[Slow Car Sport Mode]

Run it with cap off, see if you see bubbles... question for those who would know if, frequent (interval?) changes of cheap 50/50 EG coolant mix will help the fragile head gaskets on these engines any.

Yeah Subaru sold a sealer, it's like K-seal or a rebadged bottle of Holtz. Can block different passages.. im not sure I'd use it. Wood pulp milky looking sealer.

Again, EZs didn't have this issue, neither did Turbo EJs as far as I know.

 

[slacktide_bitog]

Had a 1998 ? Or 1999 EJ25D. Returned to dealer and we got something else... it's lighter than a Gen2.. interior a little smaller, in my opinion...

The first gens are charming... 2nd gens are the best and go from there. The third gen sedan really is a looker, as are 2nd Gen SUS.

Let's either LS or 2JZ swap ours, then no more leaks. Single turbo 1000+hp, AWD delete by default....



"Turbo" EJ255/257 head gaskets, sir... yes, sealers, but I've always been told that's not the proper method for that kind of thing. Even though Subaru said it was.

98 was the only year the Forester got the EJ25D
The 99+ Forester got the EJ251

Subaru coolant conditioner is required with every antifreeze replenishment; 2 years max for coolant. I swap the thermostat, o-ring, coolant, and SCC like a Swiss watch every 24 months.

I’ve personally never had a HG fail; I have had several that had a little oil seepage from the bottom of the head but it’s just a trickle & never amounts to more than 1/8” on the dipstick on a 6k OCI.

I’d personally only use a Subaru radiator cap but like you said a ‘98 is one of the high-risk years. Best of luck!

The coolant conditioner doesn't work on the DOHC EJ25D, though it is more successful on the SOHC EJ251 that leaks externally

Also, that conditioner (Holts) is a band-aid. Subaru should've just replaced every head gasket, stopped making any 2.5L EJ and gone back to the EJ20 and EJ22.

While Subaru radiator caps are probably the best to use, the Sankei cap is still a quality cap. I would never use aftermarket Motorad garbage.

Run it with cap off, see if you see bubbles... question for those who would know if, frequent (interval?) changes of cheap 50/50 EG coolant mix will help the fragile head gaskets on these engines any.

Yeah Subaru sold a sealer, it's like K-seal or a rebadged bottle of Holtz. Can block different passages.. im not sure I'd use it. Wood pulp milky looking sealer.

Again, EZs didn't have this issue, neither did Turbo EJs as far as I know.

It did have bubbles, but the bubbles stopped after I used the head gasket sealer

The Holts is ginger-based and reacts with air, which works fine for external leaks like the SOHC engines have, but it does nothing for internal leaks like the DOHC suffers from. The Bars Leaks sealer I used works by reacting with hydrocarbons from the combustion gases pushing the coolant out. This is why it works for internal leaks when ginger doesn't.

 

[SubieRubyRoo]

Subaru should've just replaced every head gasket, stopped making any 2.5L EJ and gone back to the EJ20 and EJ22.

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.

 

[Slow Car Sport Mode]

I have a bad feeling about this one, this could get real expensive real quick. If it overheated there is a good chance a rod knock could be right around the corner if it isn't already.
The cases may need to be decked as well as the heads planed. then comes the question while it is all apart what other work should be done eg valve job, guides, rings, bearings, line bore the cases, etc.

There is no half stepping when repairing this engine even properly cleaning the case decks and planing the heads using a MLS gasket may not be enough to prevent premature failure of the new HG.
When they overheat the cases expand too much around the crank which allows the crank to get tight, it also twist the cases causing to main bearing bores to go out of alignment.

The cost of machine work is very high today, when I do these for other people I use a brand new Subaru OE short block and have the heads done with 6 stars MLS viton coated HG, absolutly no copper coat.

Another cause for HG failure is broken ground straps from the heads to the frame, I replace them with 1.5" braided plated copper straps as well as adding addition grounds.

Six star is great, another solid choice is OE EJ255/257 for that.

I wonder if this engine would like M1 15W-50. (But that's oil not coolant.) Sloshing sounds from the dash.. are THOSE common on EJ platform?

 

[nthach]

I wonder if this engine would like M1 15W-50. (But that's oil not coolant.) Sloshing sounds from the dash.. are THOSE common on EJ platform?

Time to see if all the air is purged from the cooling loop. If not, a BHG(confirmed via leak down or coolant gas check) might be the best possible guess.