Subaru Head Gasket Problems Explained

[Bluestone]

I've been searching the internet to get more info on the dreaded EJ25 head gasket issue ('cause knowledge is power, right?); we who own Subes with the EJ25 engine are, of course, living with a Sword of Damocles hanging over our heads (heh, heh, nice pun, no?).

I came upon an interesting blog site written by Justin Stobb, the chief honcho of "All Wheel Drive Auto", an independent repair shop in Kirkland, Washington.

He has a section on head gasket issues: http://allwheeldriveauto.com/subaru-head-gasket-problems-explained/. Some really good info there; check it out.

It seems that Subaru dealers take the quick and dirty approach when replacing head gaskets....doing the work with the engine in the car, which Stobbs advises against. Here's what he says:

 

One of the things I comment on a lot is the repair technique used at the dealer. The typical repair is to replace the left side head gasket in the vehicle. It is impossible to obtain the same quality seal you would if you were to remove the engine from the vehicle and make the repair. But under warranty the only thing Subaru is going to pay for is the repair in the car. Here is why the repairs under warranty don’t seem to last as long. On a horizontally opposed engine you are constantly fighting gravity and fluids trying to drip out of the engine block also there isn’t as much room to clean and prep the engine block and a lot of technicians result to using a “whiz wheel” to clean the gasket surface rather than a block sander not to mention visibility isn’t all that good in the car as well.

 

The right way to repair Subaru head gaskets is to remove the engine from the vehicle and put it on a stand. This ensures a good clean repair, the number one rule when trying to replace any gasket on any engine, is to make sure the surface is clean. The “repair it in the car method” leaves a lot to be desired.

 

The best advice I have, is to not have the repair done in the car. And not done by the dealer. What I think is lost, is that a vehicle repaired under warranty is going to be fixed as quick as possible, worse is that once a dealer technician is used to doing the repair a certain way that’s how it is going to be done regardless of who pays the bill.

 

Doing the head gasket work with the engine out of the car, though, would cost a feckin' fortune, I'd imagine. Ah well,

I guess I'd best keep several grand in reserve for the eventual head gasket failure...sigh...

[scrapdaddytatum]

i can remove the motor in about 45 minutes

so removing the engine should NOT cost that much more

i have no idea why any mech would want to do that job in the car

and why anybody would do just one side

but then again

90% of my customers are stolen from the dealer

and there must be a reason for that

i can have a 2.5 out and striped in 2.5 hours

and back together and in, in 3.5-4

but i dont rush, kinda got a slow pace around here

[scrapdaddytatum]

but that doesnt answer the real question

why the heck do these damn 2.5's love blowing HG's

any body know excactly what the flaw is

i know its the HG

but the 2.5 is real sesitive

a little rad troubles and she blows her HG

bad WP, blown HG

pretty much anything will couse a 2.5 to blow

even with updated OE gaskets

ive stated using cometics

we shall see.......

[SuBrat84]

I have a 2.5 apart right now.. The clearance between where the coolant flows around the cylinder is very little.. I didn't measure but not more than an eighth of an inch of aluminum. When the pressure (heat) gets too much it blows the gasket and then allows ehxaust to seep through into the coolant.. then subsequent heating/cooling of the motor will expand the leak.

[nipper]

but that doesnt answer the real question

why the heck do these damn 2.5's love blowing HG's

any body know excactly what the flaw is

i know its the HG

but the 2.5 is real sesitive

a little rad troubles and she blows her HG

bad WP, blown HG

pretty much anything will couse a 2.5 to blow

even with updated OE gaskets

ive stated using cometics

we shall see.......

 

Do a search, i have written extensivley on why, not only subaru, but why almost every mfg in the 1990's had at least one engine with a bad HG design.

 

nipper

[Rooster2]

How I heard the story!

 

 

 

I have only seen a picture and write up (never replaced a head gasket myself),the writer pointed out that the head gasket becomes defective at a point directly between the cylinders, mostly on the driver's side. The article pointed out that the 2.5 Gen 1 engine block cylinder wall between the pistons was designed too thin. Over time and with miles, the thin HG at that spot cannot withstand the strong exhaust gas pressure, and will eventually weaken, allowing exhaust gas to enter the cooling system. Hence the problem.

 

There are a lot of people on this forum that are a lot smarter then me, and with a lot more "hands on" repair experience regarding the HG problem. I am certain that they can they can explain this in greater detail then me.

 

Of note........about 3 years ago, when I purchased my 98 Legy OBW. It was only after I had owned it for a few months, that I went to a Subie Dealer for parts. I casually spoke with the Service Manager and asked about him about the 2.5 Gen 1 motors blowing head gaskets, as I had heard some industry street chatter about this being a problem. (This was before I joined this forum to read a lot about it.) The Service Manager would not acknowledge that Subarus have an HG problem. In retrospect, I now think that is very odd, considering how much is written about the problem on an ongoing basis.

[GeneralDisorder]

I call BS - his claims are entirely dependant on the technician doing the work. I can (and have) done plenty of quality HG repairs with the engine in the car.

 

His comment about fluids is baseless - just jack up each side as you go so they are slanted slightly. An inch or two is all you need to keep the fluids out of the way.

 

Surface prep is easy if you have the right tools and the knowledge to use them. Anyone that uses a roto-loc or flapper wheel, etc on HG surfaces should not be working any precision machinery to begin with.

 

Head Gaskets CAN be done properly in the vehicle. It saves time, and does not hamper a technician that knows what he's doing.

 

You can also be *too* anal about this issue. There's a point at which the sufaces can be too smooth even. The gasket requires a certain roughness to properly adhere. I could go on all day about RA, and ways of properly measureing it.... but at the end of the day all that's required is that the surfaces be flat, clean (free of gasket material, dirt, oil, fluids and solvents), and be relatively smooth - about a 600 grit finish is excelent.

 

These are not swiss watches, although some attempt to make them seem that way. Drop by my work and I'll show you machines that are far more demanding....

 

GD

[scrapdaddytatum]

thanks for all the info

 

and general, you have fun with that incar chit

 

as far as more demanding

ever worked on a horsehead v-8, not much fun there

these subarus are simple

and very forgiving

just not the 2.5

[cabron]

Do a search, i have written extensivley on why, not only subaru, but why almost every mfg in the 1990's had at least one engine with a bad HG design.

 

nipper

 

Nipper,

 

Do phase II engines blow the HG. I have been told that the Phase II engine rarely blows a HG after it has been replaced?

 

I think that means its a HG issue. ??

[Rooster2]

Nipper,

 

Do phase II engines blow the HG. I have been told that the Phase II engine rarely blows a HG after it has been replaced?

 

I think that means its a HG issue. ??

 

 

Nipper........a good point!

 

What exactly is the difference between a phase 1 and phase II motors, particularily relating to head and HG design?

[GeneralDisorder]

What exactly is the difference between a phase 1 and phase II motors, particularily relating to head and HG design?

 

Completely different - the phase I is a DOHC head. The phase two is a SOHC. Different manifolds, different gaskets, etc.

 

GD

[scrapdaddytatum]

Completely different - the phase I is a DOHC head. The phase two is a SOHC. Different manifolds, different gaskets, etc.

 

GD

 

but the gaskets are EXTREMELY similar arnt they

anybody have some laying around

i have cometic phase ones on the bench but no phase 2

i could run out to the dealer thursday and buy one

but it would get wasted, i only run cometics now

i have had the dealer gasket fail

[GeneralDisorder]

but the gaskets are EXTREMELY similar arnt they

 

Not very close at all. The Phase I gaskets are .152cm thick, while the phase II are only .058cm thick. Different design entirely, and only one third as thick.

 

GD

[subaru360]

I do a lot of these head gaskets and engines. I would never even consider doing HG's in the car. It's SO much easier to pull the engine. With the engine out and on a stand, I tip it to one side do one HG, tip it the other way and do the other. Makes for a clean neat easy job.

 

My personal opinion on why the original gaskets fail is bad design on the original gaskets. I've never had an updated gasket fail. I've also never had a warped head or block. I check them for straightness and cracks and they are always good. That makes me believe it's just a bad gasket design.

 

I shoud say I won't touch a 2.5 phase one that's been seriously overheated. I always recomend replacing those with a used 2.2 I'll only do the gaskets if I know for sure it only was running warm or got hot and was shut right off.

[scrapdaddytatum]

I do a lot of these head gaskets and engines. I would never even consider doing HG's in the car. It's SO much easier to pull the engine. With the engine out and on a stand, I tip it to one side do one HG, tip it the other way and do the other. Makes for a clean neat easy job.

 

My personal opinion on why the original gaskets fail is bad design on the original gaskets. I've never had an updated gasket fail. I've also never had a warped head or block. I check them for straightness and cracks and they are always good. That makes me believe it's just a bad gasket design.

 

I shoud say I won't touch a 2.5 phase one that's been seriously overheated. I always recomend replacing those with a used 2.2 I'll only do the gaskets if I know for sure it only was running warm or got hot and was shut right off.

 

 

i actually have never seen a straight head when replacing the HG

i have every set milled flat on CBN(nice finish)

has anybody seen a warped block???

[subaru360]

i actually have never seen a straight head when replacing the HG

i have every set milled flat on CBN(nice finish)

has anybody seen a warped block???

 

I probably don't see warped heads since I won't do gaskets if the motor was cooked. I always replace the ones that have been cooked a few times with a 2.2 instead.

[Bluestone]

On EJ25 engines, head gaskets fail (for the first time) at different mileages; some failures occur at 30k mile or even earlier, some well over 100k miles with at least one owner reporting 180k miles, and everything in between. Possibly, 60-90k miles being the most common?

What factors might account for (and be identified) the variation in mileages at which the first failure occurs?

Some factors to examine might be:

1) How the engine was initially broken in.

2) Intervals at which engine oil is changed.

3) Viscosity of oil normally used

4) Does synthetic oil, regularly used, make for a "friendlier" environment for head gaskets?

5) Does the octane of the gasoline regularly used make a difference? Here, in northern California, 87, 89 and 91 octane is common. Does the lowest octane gas make for a "harsher" environment for head gaskets in the upper combustion chambers?

6) Does the type of air filter, how dirty it gets and at what intervals it's changed make any ultimate difference to head gasket life? Would a K & N type filter, by allowing more air into the combustion chamber, make for a "friendler" environment?

7) Does the fact that head bolts are not retorqued at regular intervals contribute to earlier head gasket failure?

Of course, it's a "no brainer" that low silicate anti freeze/coolant(i.e.,Subaru's OE) be used and changed pretty regularly.

 

The upper cylinder wall of the EJ25 engine, where the head gasket contacts the combustion chamber, is, as I understand it, rather thin, and is a weak point. And head gasket material is important, with the latest ones supposedly being more robust.

If head gaskets are replaced with the latest versions, on both heads and with the engine out of the car and the head surfaces carefully prepared, can one expect long head gasket life thereafter, i.e., at least 150k miles? ( As I mentioned earlier, there are some...although not many, apparently, EJ 25 engines that DO go 150k miles on the original gasket. Why?)

Or is the EJ 25 engine, because of its design, just doomed to earlier head gasket failure (for most of us) regardless of what one does?

[idosubaru]

I call BS - his claims are entirely dependant on the technician doing the work. I can (and have) done plenty of quality HG repairs with the engine in the car.

 

Head Gaskets CAN be done properly in the vehicle. It saves time, and does not hamper a technician that knows what he's doing.

 

yup. if a tech paid by the job, instead of by the hour, is going to shortchange anything by doing it "in the car"...he's not going to all of a sudden take his time, do things right, and properly just because the engine is out of the car. that point makes no sense really. either the person doing the job is going to do it right or not....paying job rates like dealers and shops do does not give the customer the best possible workmanship. usually it's sufficient, but it's still not top shelf.

 

head gaskets can be done quicker in the car for sure. it is nice to have them out and also is advisable sometimes...like for doing a clutch as well. but in general pulling and installing takes quite a bit of time..if it didn't dealers would be doing it.

[subaru360]

yup. if a tech paid by the job, instead of by the hour, is going to shortchange anything by doing it "in the car"...he's not going to all of a sudden take his time, do things right, and properly just because the engine is out of the car. that point makes no sense really. either the person doing the job is going to do it right or not....paying job rates like dealers and shops do does not give the customer the best possible workmanship. usually it's sufficient, but it's still not top shelf.

 

head gaskets can be done quicker in the car for sure. it is nice to have them out and also is advisable sometimes...like for doing a clutch as well. but in general pulling and installing takes quite a bit of time..if it didn't dealers would be doing it.

 

If you're doing head gaskets, it's 10 more bolts and the engine is out. 4 bellhousing, 4 torque converter and and 2 engine mount. You'd be nuts to lean over a fender, kill your back and not have room to work or see trying to do them in the car.

[Gloyale]

If you're doing head gaskets, it's 10 more bolts and the engine is out. 4 bellhousing, 4 torque converter and and 2 engine mount. You'd be nuts to lean over a fender, kill your back and not have room to work or see trying to do them in the car.

 

It adds a bit more than that. It all depends though. EJ18,22, I'll do in the car all day. EJ25 I would probably pull. Old EA82s I'd definately leave in he car. I've never done anything older

[subaru360]

It adds a bit more than that. It all depends though. EJ18,22, I'll do in the car all day. EJ25 I would probably pull. Old EA82s I'd definately leave in he car. I've never done anything older

 

I do at least one of these a month. It's literally 10 more bolts, nothing else if you have the heads off the engine.

 

If you're doing HG's you have the intake off, all the wires umplugged, all the hoses unhooked, radiator out, a/c compressor flipped over, ps pump sitting on the fender, exhaust dropped.

[keltik]

I visited the local engine rebuilder yesterday and i would just like to add what he told me to the discussion. The re-design on the gaskets had 2 factors in reducing HG failure.

 

1) The gasket was much thinner - thinner means less pressure on the weak point.

 

2) From what ive seen the newer gaskets look a bit reinforced around the cylinder edge. Theyre also made of a different multi-layered steel design that tolerates uneven surfaces better.

 

I could be wrong but ive heard the newer EJ25 motors were simply fitted with the uprated gaskets rather than redesigned to remove the underlying cause.

[subsince77]

On EJ25 engines, head gaskets fail (for the first time) at different mileages; some failures occur at 30k mile or even earlier, some well over 100k miles with at least one owner reporting 180k miles, and everything in between. Possibly, 60-90k miles being the most common?

What factors might account for (and be identified) the variation in mileages at which the first failure occurs?

Some factors to examine might be:

1) How the engine was initially broken in.

2) Intervals at which engine oil is changed.

3) Viscosity of oil normally used

4) Does synthetic oil, regularly used, make for a "friendlier" environment for head gaskets?

5) Does the octane of the gasoline regularly used make a difference? Here, in northern California, 87, 89 and 91 octane is common. Does the lowest octane gas make for a "harsher" environment for head gaskets in the upper combustion chambers?

6) Does the type of air filter, how dirty it gets and at what intervals it's changed make any ultimate difference to head gasket life? Would a K & N type filter, by allowing more air into the combustion chamber, make for a "friendler" environment?

7) Does the fact that head bolts are not retorqued at regular intervals contribute to earlier head gasket failure?

Of course, it's a "no brainer" that low silicate anti freeze/coolant(i.e.,Subaru's OE) be used and changed pretty regularly.

 

The upper cylinder wall of the EJ25 engine, where the head gasket contacts the combustion chamber, is, as I understand it, rather thin, and is a weak point. And head gasket material is important, with the latest ones supposedly being more robust.

If head gaskets are replaced with the latest versions, on both heads and with the engine out of the car and the head surfaces carefully prepared, can one expect long head gasket life thereafter, i.e., at least 150k miles? ( As I mentioned earlier, there are some...although not many, apparently, EJ 25 engines that DO go 150k miles on the original gasket. Why?)

Or is the EJ 25 engine, because of its design, just doomed to earlier head gasket failure (for most of us) regardless of what one does?

 

I know nothing, but that has never stopped me from jumping into these discussions. As the owner of a 97 OBW that just started the blown headgasket routine at 197,000, I can assure you that some do go this long. I know a few others in this area that are now between 140k and 160k without having failed. My question is, would living at 8000, to 9000 feet, and doing a lot of highway driving be better for the headgasket situation. I take really good care of my engine in terms of oil, filters, and ignition parts etc., but the lowest this car ever lived was about 6500 feet in Durango for a while. just wondering.

[screwbaru2]

I wouldn't know. The 2.5's I've owned are where they belonged in the 1st place. SCRAPPED!!!

[idosubaru]

i doubt it. these engines are getting old age wise and we're loosing site of the fact that they blew even at 30,000 miles. i doubt maintenance or elevation has much to do with it. you're in a high density subaru area, that's probably a good reason there's still many around. it's been hashed out over and over on other threads, you can read through those for more opinions and ideas.