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Discussion Starter #1
I’m pretty sure my head gaskets are starting to fail again on my 08 Outback 2.5i. The first time was around 99,000 miles, currently have 168,000. I was checking out parts on Rockauto.com, and wondered about the quality of head gasket sets. I know that Felpro are supposed to be good, but that’s what I used the last time. Anyone had experience with Enginetech brand? The set is less than half the price of Felpro. They also have headbolts, which I think I may replace this time. I’m not going to risk it if there is any question, saving lots of money doing it myself anyway. Also wondering if I should consider doing a valve job this time around. The car still runs great and doesn’t seem to exhibit signs of valve wear. It doesn’t even use excessive amounts of oil.
 

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No knowledge of Engintech brand. I'd use Felpro, Six Star, or Subaru XT multi-layer only. When I did my 2008 2.5i NA at 104k, I had the shop use Six Star.

Did you resurface the heads when they were replaced at 99k?

No oil consumption at 168k is very good, BTW. I'm at 134k on mine at the moment, and it's slowly increasing usage, perhaps a quart in 2k miles.
 

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I’m pretty sure my head gaskets are starting to fail again on my 08 Outback 2.5i. The first time was around 99,000 miles, currently have 168,000. I was checking out parts on Rockauto.com, and wondered about the quality of head gasket sets. I know that Felpro are supposed to be good, but that’s what I used the last time. Anyone had experience with Enginetech brand? The set is less than half the price of Felpro. They also have headbolts, which I think I may replace this time. I’m not going to risk it if there is any question, saving lots of money doing it myself anyway. Also wondering if I should consider doing a valve job this time around. The car still runs great and doesn’t seem to exhibit signs of valve wear. It doesn’t even use excessive amounts of oil.
1. Use Subaru gaskets....Fel Pro and Cometic are additional options but they're not necessary, significantly cheaper, or better, and muddy the water. Six Star is just a rebranded Cometic gasket. Cometic is the go to source if you need different thicknesses for a custom situation.

2. Reuse the headbolts if they're original. clean the threads in the block and the bolts and properly lubricate the bolt threads.

If the headbolts were replaced last time - I'd get Subaru bolts when doing it the second time - either new or used and clean them. I've seen repeat failures of engines with Fel-Pro replaced headbolts....maybe an outlier, labor mistake, or possibly a false sense of security with poor choice of focus on bolt replacement, but it's pointless except you get to avoid cleaning the old threads. I would only use Subaru bolts given Fel Pro makes the erroneous claim to replace headbolts without any proper qualification regarding the Subaru design engineers who say not to replace them. if you're going to go against the design engineers on a problematic area, please describe in statistically meaningful terms why.

3. resurface the heads and adjust the valves. they don't need checked or full valve job, waste of time.

You don't need an entire kit, you only need: Subaru headgaskets, intake manifold gaskets, and exhaust manifold gaskets. Coolant cross over orings and valve cover gaskets are a good choice while you're in there. Nothing else ever really fails or is problematic.
 

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Discussion Starter #4
1. Use Subaru gaskets....Fel Pro and Cometic are additional options but they're not necessary, significantly cheaper, or better, and muddy the water. Six Star is just a rebranded Cometic gasket. Cometic is the go to source if you need different thicknesses for a custom situation.

2. Reuse the headbolts if they're original. clean the threads in the block and the bolts and properly lubricate the bolt threads.

If the headbolts were replaced last time - I'd get Subaru bolts when doing it the second time - either new or used and clean them. I've seen repeat failures of engines with Fel-Pro replaced headbolts....maybe an outlier, labor mistake, or possibly a false sense of security with poor choice of focus on bolt replacement, but it's pointless except you get to avoid cleaning the old threads. I would only use Subaru bolts given Fel Pro makes the erroneous claim to replace headbolts without any proper qualification regarding the Subaru design engineers who say not to replace them. if you're going to go against the design engineers on a problematic area, please describe in statistically meaningful terms why.

3. resurface the heads and adjust the valves. they don't need checked or full valve job, waste of time.

You don't need an entire kit, you only need: Subaru headgaskets, intake manifold gaskets, and exhaust manifold gaskets. Coolant cross over orings and valve cover gaskets are a good choice while you're in there. Nothing else ever really fails or is problematic.
That’s all really helpful info. I just bought gaskets (not the complete set) I needed the first time, but was also doing the timing belt/water pump. I reused the original head bolts the first time, just didn’t know if I should push my luck again. I didn’t resurface heads, but I checked them for flatness and warp. I might take to a machine shop and have them resurfaced. I don’t think I’ll do a timing belt right now either, it’s not all that hard to do later. Who knows if I will keep the car for another 30k miles anyways.
 

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Discussion Starter #5
No knowledge of Engintech brand. I'd use Felpro, Six Star, or Subaru XT multi-layer only. When I did my 2008 2.5i NA at 104k, I had the shop use Six Star.

Did you resurface the heads when they were replaced at 99k?

No oil consumption at 168k is very good, BTW. I'm at 134k on mine at the moment, and it's slowly increasing usage, perhaps a quart in 2k miles.
It does use some oil, maybe 1 quart between oil changes, but I’ve always used Amsoil synthetic oil with yearly drain intervals. The past few years I switched to semi annual drain intervals, probably 8000 miles between changes. I did that because I was adding 2 quarts or more on the yearly schedule. When I switched to semi annual, I stepped down to their OE series oil, which is still rated to go up to 10k.
 

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I didn’t resurface heads
There it is.

Provided you checked flatness with a precision, machinist straight edge--not a stamped ruler--the issue likely comes down to surface finish.

You got almost 70k miles out of it before needing them done again, which I'd say is pretty good.

I disagree on waiting for the timing belt service if you're going to drop in a new gasket set. The USDM Subaru's are the only in the world (that I'm aware of) where Subaru suggests a 105k mile timing belt replacement interval and I've read it's because there's a law that no new car sold in the US can require a major service before 100k miles. Everywhere else in the world, from what I understand, Subaru timing belt intervals is on a 60k mile schedule. Look around at timing belt failures--they aren't unheard of. Often the failures are aftermarket components, but even still, at 70k miles on your current belt/idlers, even if you used Subaru parts, I'd say you're probably on borrowed time.
 

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Are you aware that properly GROUNDING the heads (electrically) is imperitive to a long-lasting head-gasket job? If not grounded, all the high-voltage from the ignition system is forced to arc thru the head-gaskets to complete the circuit. (do not assume the headbolt threads will make solid electrical contact.)

Some mechanics do not reinstall the factory head-ground straps after replacing gaskets.
 

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Discussion Starter #8
Are you aware that properly GROUNDING the heads (electrically) is imperitive to a long-lasting head-gasket job? If not grounded, all the high-voltage from the ignition system is forced to arc thru the head-gaskets to complete the circuit. (do not assume the headbolt threads will make solid electrical contact.)

Some mechanics do not reinstall the factory head-ground straps after replacing gaskets.
I did reattach the ground straps. I would concede that maybe the heads were not machined the first time (as @aesthetic.rake suggested ) may be the cause of failure. I was ,of course, trying to save a few bucks and didn’t want to needlessly pay for resurfacing. But I almost think that there is no getting around doing it every 100k or so.
 

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Discussion Starter #9
There it is.

Provided you checked flatness with a precision, machinist straight edge--not a stamped ruler--the issue likely comes down to surface finish.

You got almost 70k miles out of it before needing them done again, which I'd say is pretty good.

I disagree on waiting for the timing belt service if you're going to drop in a new gasket set. The USDM Subaru's are the only in the world (that I'm aware of) where Subaru suggests a 105k mile timing belt replacement interval and I've read it's because there's a law that no new car sold in the US can require a major service before 100k miles. Everywhere else in the world, from what I understand, Subaru timing belt intervals is on a 60k mile schedule. Look around at timing belt failures--they aren't unheard of. Often the failures are aftermarket components, but even still, at 70k miles on your current belt/idlers, even if you used Subaru parts, I'd say you're probably on borrowed time.
I’ll take your advice about the timing belt, I know nothing about Subaru world maintenance schedules, but I’ll take your word for it because I know that the standards for other makes are different around the world, based on the country’s regulations.

Re: the valves, are the rubber seals on the valves that may need replaced? I don’t recall offhand what is in there.
 

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I’ll take your advice about the timing belt, I know nothing about Subaru world maintenance schedules, but I’ll take your word for it because I know that the standards for other makes are different around the world, based on the country’s regulations.

Re: the valves, are the rubber seals on the valves that may need replaced? I don’t recall offhand what is in there.
I think headgaskets are a maintenance item too--every ~100k.

I've never had the valve seals done. My machinist, who handles all of the local Subaru dealership's machine work, claims them not necessary to do as the oil doesn't physically sit on them unlike that of a "normal" inline engine. YMMV, but I've taken his advice but I'll admit I'm not the person to ask about it.
 

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Discussion Starter #12
I concur with grounding.
If the HGs are failing due to oil leakage, then my question is was MLS gaskets used?
If the HGs are failing due to coolant consumption, then there may be another issue with temperature control.

If it's oil, check this out: https://www.subaruoutback.org/threads/ej-head-gasket-leak-experiment.512591/
Mine is primarily coolant seepage. It is just starting to get the telltale smell when I shut it off. I used Felpro gaskets. I doubt there is any lack of good grounding, but I will verify when I get ready to work on it. I have a PowerProbe that will tell if if the ground is good. It does not overheat or even run hot, the radiator was replaced sometime after the head gasket was done and I’ve never added anymore coolant since then. Just thinking it’s the nature of the beast. All in all, very low maintenance on this car.
 

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I think headgaskets are a maintenance item too--every ~100k.

I've never had the valve seals done. My machinist, who handles all of the local Subaru dealership's machine work, claims them not necessary to do as the oil doesn't physically sit on them unlike that of a "normal" inline engine. YMMV, but I've taken his advice but I'll admit I'm not the person to ask about it.
Respectfully, a head gasket should be a "forever" item on an engine. They are not a normal maintenance item that gets replace every (say) 100,000. No manufacture has a head gasket as maintenance. Well, except for a Fiat or Yugo from the 1980's.
 

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Discussion Starter #14
Just stating the facts, they have a weak spot. That's why there is a whole thread to log this issue. I agree that it shouldn't be something we
Respectfully, a head gasket should be a "forever" item on an engine. They are not a normal maintenance item that gets replace every (say) 100,000. No manufacture has a head gasket as maintenance. Well, except for a Fiat or Yugo from the 1980's.
Should be, but not reality for a lot of 2.5i Subaru owners, unfortunately.
 

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Subaru isn't the only one with weak gaskets. Every Ford/Mazda 4 cylinder tends to blow the head gasket without warning as early as 120k miles. When it starts weeping, you don't notice it, then one day you go out to start the car and it's blowing white smoke. I've seen it plenty. Reason: single layer gasket with graphite blend on both sides.

Granted, a HG should not be a maintenance item, but when it's a know issue, it becomes one at least the first time around so it can be replaced with an improved gasket.

Manufacturers may not put a HG in their maintenance schedule, but they also defer from putting transmission fluid on it as well. Research your cars and learn about them.
 

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Everyone touts the MLS gasket as being the savior of the sohc ej25 because the turbo'd, dohc ej25 isn't prone to headgasket failures and the obvious difference is the MLS gasket. For whatever reason, the extra, outer cylinder wall supports cast into the block of the ej255/7 get ignored. These supports severely cut down on vibration/cylinder wall movement/flex, which in turn, cut down on head gasket "wear."

Since I've had the unfortunate experience of tearing the top end off a sohc ej25 that recieved a fresh set of SixStar gaskets nearly immediately after the engine was installed, I can attest that a part of the design of the "improved" gaskets is to (IMO) attempt to mechanically lock the top of the cylinder wall/face of the block to the head. There's a thicker ring inside the improved gaskets that doesn't compress like the rest of the MLS gasket. This ring I believe is intended to indent itself into the head/block to try and prevent this vibration or movement.

I ended up tearing apart the engine I mentioned above due to an air pocket that I mistook for a blown head gasket (coolant violently erupting out of the radiator.) Pulling the heads back off and taking them down to be milled again, the machinist pointed out the "dent" caused by this ring and this has had me thinking about it for the last year and a half or so since then.

The other day, this guy posted this on Youtube. He's deliberately milling a groove into the surface of the block and installing a copper wire to put more pressure, and a harder material, against the head gasket/head in that area and it got me wondering if what I saw on the engine I mistakenly tore back apart was what was actually going on.
 

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Discussion Starter #17
I ended up tearing apart the engine I mentioned above due to an air pocket that I mistook for a blown head gasket (coolant violently erupting out of the radiator.)
Yes, I almost made that mistake last time, but fortunately, I checked further before I tore it down. Interesting video, if I were building a performance ej25, that might be something to consider, but not for everyday driving.
 

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Yes, I almost made that mistake last time, but fortunately, I checked further before I tore it down. Interesting video, if I were building a performance ej25, that might be something to consider, but not for everyday driving.
I think you missed the point of why I posted the video. It wasn't to suggest you do that, it was to suggest the "improved" gaskets have a similar idea--this guy, who is building way way performance engines, has simply taken it to the next step.

It's all theoretical nonsense anyways. I probably shouldn't have posted it since it sort of derails your thread.
 

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Discussion Starter #19
On the contrary, I appreciate the discussion.
Maybe I didn’t completely get it, but I got the similarity. I guess I took it to say the improved gaskets weren't improved enough to do the proper job. 🤷🏻‍♂️
 

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Not sure about the experience of others but the head gasket failures I have seen on the EJ25 SOHC motors have never involved the compression area of the cylinder. The ones I have seen have always involved either the water jacket leaking to the outside of the engine and/or the oil galleries leaking to the outside of the engine.

This is why texting for combustion gases in the coolant is not a good test for failed head gaskets in EJ25 engines.

I am aware that some people report a failure in the combustion chamber part of the head gasket but I have never seen one myself, maybe because I choose to replace the head gaskets when there are signs of coolant or oil leaking.

Seagrass
 
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