WAWalker

Will be easier for you with engine out. EJ22 is ~8 hour job pulling engine and replaceing head gaskets, t-belt, w/p, R&R reseal oil pump, replace crank seal............ EJ25 is ~10-12 for same. If you have done a few and have all the right tools and equiptment. This is time spent working, not figureing takeing heads to machine shop to be checked/milled. For your first or second time, figure on considerably more time.

The distance from the inside edge of the coolant passages to the inside edge of the fire ring is ~4-5 mm at every passage.

Edited due to lack of thechnical content.

No. Angle torqueing provides for a more even tightening of the bolts. Turning the bolt x deg. is going to thread the bolt in so far, the thread pitch on all the bolts is the same. If you turn all the bolts in the same amount of deg. they are going to all be tightened more evenly. The ft lb. torque numbers are not even do to factors beyond our control. Friction between bolt threads and block threads, bolt head and washer, washer and cylinder head, mainly. It may take more force to turn one bolt in a quarter of a turn than the next bolt. Make sense? Go to the link that RallyKeith posted. This is explained very well there. Something like 90% of the torque applied to a bolt is used to over come this friction. It is a good read. Thanks, RallyKeith:)

I have read the info in this link. I think you may be on to something. This is why I look for imput from others. I don't have the patiance to search for all this stuff. I'm still learning and there are many people smarter than me who can help. I still don't think that Subaru uses "Torque To Yeild" head bolts. There is nothing in the '99 FSM (lastest DOHC service manual) about replacing the head bolts. The torque proccedure specificly states, to be sure that finale torque angle does not exceed 180 deg. This could very well be to prevent torqueing these bolts to the point of "YEILD". The info in your link explains the difference between "torque to yeild" and "torque to angle" and the advantages and dissadvantages of. From the link............................................................................................................................................................ "With the classic style head bolt or stud, the tensioning below yield does provide a very steady clamping force. The steadiness of the clamp is the problem. With the use of aluminum cylinder heads, the needs for clamp changed. Instead of a maximum clamp applied being optimal, a steady clamp that can allow for the thermal expansion of the aluminum head without exceeding the compressibility of the head gasket became more important. The classic head bolt or stud does expand and allow for some thermal expansion, but the flexibility was not quite optimal. When the aluminum head warms up at full operating temperature, it grows in size, putting more bolt tension on the head gasket, and on the aluminum itself. This results in brinelling of the head surface where the fire rings of the head gasket are located, overcompression of the HG itself, and distortion of the aluminum around the head bolts. If the HG cannot handle the excessive pressure that occurs, it will remain permanently thinner; so that when the engine cools down, the HG does not provide as good a seal between the head and block. Over time, this will lead to HG failure. Enter TTY. By stretching the bolt beyond the yield point, and into the plastic range, the maximum clamp applied is reduced; but by being in the plastic range, the bolt can and does give more with the thermal expansion of the aluminum head. The clamp is not as great; but it is steadier throughout the temperature range...a very important thing when using aluminum for head casting material. HG longevity is increased; and brinelling and distortion of the head is reduced." ................................................................................................................................................................................ This could explaine the "wear" that I noted between the head gasket fire ring and cylinder/cylinder head matting surfaces. As I said the "gass cutting/erosion" crossed my mind and made sence, but on closer inspection there was an absences of discoloration from combustion gases leaking by. The discoloration was there, but not over the entire area of "wear". So if the head bolts and torque proccedure used on these engines truely are not "torque to yeild", it is very possible that torque to yeild bolts and torque proceedures would help. And a "torque to yeild head gasket" would only make the problem worse. As described above, that is the problem with to much clamping force on a head gasket. Once the gasket "yeilds" it can't maintain the seal. Bad day when you don't learn something.

The point I was trying to make here is..........................Head gasket replacement on 2.5L DOHC Subaru engines before complete failure (over heating) is good maintanence. And as a rule, should be paid attention to and considered a possible maintanence replacement item after another 100k or so if it is desirerable to keep the car on the road. If the open deck block design is the major contributor, then failure of any gasket design is a possibility. If repeat failure is even a remote possibility, with the updated gaskets, this would pertain to vehicles with rebuilt engines also.

Edited due to total lack of technical content.

The more I looked at that engine block while it was appart, the less convinced I am that the worn area on the heads and block where the gasket seals is all from the combustion gases blowing through. I wiped the ends of the cylinders clean and could only see one small spot in the wear area that had any real discoloration from the combustion leak, the rest of the wear area was nice and shiny. So I'm still leaning toward cylinder vibaration due to the open deck as the leading cause of the failed head gaskets. Still not convienced that there is any new head gasket that will fix this permenently. Help, maybe. Fix, I don't believe so. Next week....................a '97 2.2L with a combustion leak into the cooling system. Stay tuned for pictures of the 2.2L block and heads.

Ok, it's a done deal. Here are the finale ft lb. torque numbers on the head bolts. Left bank Right bank 1 & 2 @ finale 180 deg of torque angle. 1- 84.4 1- 77.6 2- 82.6 2- 81.4 3, 4, 5, & 6 @ finale 135 deg of torque angle. 3- 72.5 3- 66.5 4- 71.5 4- 66.9 5- 76.5 5- 66.3 6- 66.7 6- 68.3 Now to find out at what point these bolts yeild. I have no way of testing this. Anybody else?

This can be debated for sure. But you also can't use the arguement that if someone is selling head bolts they should be replaced. If someone is trying to sell me somthing, they are trying to make a living, dosen't mean I need what they are selling. I don't replace head bolts because it hasn't proven to be nessasary for successesful repair. I am curisous Nipper, what changed your mind on this. In the old thread referanced here, you said "never reuse", now you say it is OK. Just wondering what factor changed your mind. Later after reassembly of this engine I will post final ft lb. torque numbers for these head bolts. Snap-On's TECHANGLE wrench reads torque angle w/o the need for a seperate gage, and at the same time records final ft lb. torque. Should be interesting.

No I do not replace head bolts. Don't know of to many people who do. Dealers will do most anything and spend as much of your money as they feel the need to in order to limit their liability. The last I heard, and I hope Emily will correct me if I'm wrong, CCR doesn't install new head bolts. They say to go ahead and reuse them. Emily?

Well, I've done 30+ DOHC head gasket replacements with not one comeback for rod bearing failure or anything eles. I see a lot of first timers come though the shop with new head gaskets that have been installed eleswere still running strong. I don't hear from other shops about rod bearing failure after head gasket jobs. So just have not seen this as a problem on the DOHC engines. SOHC, different story. Have seen more rod bearing failure in the last year with them, than DOHC's in the last 5 years. Maybe I'm just not looking in the right place.

I assume you are refuring to the SOHC 2.5L. Yes, I have seen this with the SOHC engine before and after head gasket replacement, due to oil comtamination from the coolant leak. Rod bearing failure in the DOHC is fairly uncommon due to oil comtamination. I don't see antifreeze contamination as a problem in the DOHC engine, but have seen MANY that have had the oil hot enough to melt the sickers off oil filters, and bubble the grippy stuff on the FRAM oil filters. Have seen them hot enough to seize the pistons in the cylinders (they usually run after cooled down). That kind of heat and expantion of parts ain't doing the bearings, rings, or pistions any good, and they ain't going to last after that. The DOHC head gasket leak is a funny thing. Try to diagnoise it on a cold engine, probably not going to find it. This is a big reason why so many of these cars get t-stats, water pumps, and radiator thrown at them before anyone decides to fix the head gaskets, by that time they have probably over heated enough times that they are questionable for repair. It dosen't leak all the time. Normally the leak will only occure when the engine is at full opperating temp. and under load. Idleing, and in town driving, more often than not will not cause leakage. When driven at highway speeds there is enough combustion chamber pressure to push past the gasket. There isn't enough cooling system pressure to push coolant into the combustion chamber. There for no antifreeze contamination of the oil. But as I keep saying. The SOHC head gasket failure is a different animal. And one I would like to discuss. Mixing the two in the same thread only causes confusion though.

Don't believe so.

My thoughts exactly. Without many on the road that are not at the aproximate miles of original failure, you can't expect anything more. This maybe true. But............................. 2.2L Subrau engines have been know to go 300k still running strong. There is not that much difference between the lower ends, so why can't a 2.5L do it. I think the demise of most 2.5L DOHC's is over heating due to head gasket failure. Repeat and/or severe over heating takes a toll on the entire engine. My veiw on this is......................If people would just accept the fact that the head gasket failure is a real problem and will most likely happen to their DOHC 2.5. Then maintanance can be approched is such a way that the head gasket failure can be taken care of before it leads to over heating, in turn avoiding unessasary engine wear. And likely provide a longer engine life. I have replaced head gaskets on these engine with as little as 88k and as much as 189k. Is it prudent to replace head gaskets on a 189k mile engine? If it's not using oil, doesn't have pistion slap, compression is good, and the owner doesn't want to buy a new car? Now if the replacement gaskets start failing on these engines at the same aproxament milage as the origanals did...............the engine that would be pushing the 300k mile mark wouldn't be a canadit for another repair, but the one that would be pushing the 200k mark, if everything eles checked out, why not.

Have any of you guys in WA talked to Bobby Long? He is the Toyota front axle and birfield guru. Has expaned into may other drive train areas, offering cryoed & chromo parts. Hub gears, cryoed ring and pinion........ Don't know if he treats the parts himself or not. He is in Grahm WA. Don't know if he would be interseted in messing with Subaru stuff, but couldn't hurt to vist with him.

So you feel that the "updated" gasket is a sure fix and under normal operating conditions it should not fail again?

The '97 2.5 has EGR and duel port exhaust. The only 2.2 with EGR and duel port exhaust was built in '95. '96 they went to signal port exhaust. If you want a direct replacement 2.2 for a '97 2.5, that is the only one. You can us other MY 2.2L engines but it is not a direct fit. You will have to mix and match parts. Like exhaust, intakes, Evap emission lines, drill & tap earlier heads for EGR (this can't be done with some early heads). None of which is a big deal if you have good acess to spare parts.

You will need a '95 2.2 w/ EGR for a straight forward swap.

The '00 on EJ25's are SOHC engines. Different animal. I would like to get to the bottom of that problem also. What is the fix you speek of for the '03 and later?

This is a '99. But ALL DOHC '97-'99 have the SAME failure. As I said the leakage is at the bottom of the cylinder. Were the dicoloration is. It is most obvious on the cylinder head. I didn't wipe the block off before taking the pic, so some of what you see there is the coating from the old gasket. Gas erosion came to mind last night after posting. That makes perfect sense. It is not just two cylinders it is all four. I just took pictures of the worst side. One other note: This is the left bank. The right bank has more (thicker) support at the tops of the cylinders. Failure on the exhaust side of the head is probably not coincidence. What I am trying to get at here is the root of the problem. This does not happen to just a few of these engines. It will IMO happen to all of them. Why is it happening? Without know this, how can we be sure that a different head gasket will prevent it from happening again?

The left hand bit is a very good idea. The big thing when trying to drill out a broken bolt is to dill it in the center. If the bit doesn't grab and turn the broken peice out you will want to continue to drill through the bolt, and try an extractor. If the extractor dosen't work, your last chance is to drill as much of the bolt out, as close to the threads as possible. Hear is where it is improtant that your first hole is in the center of the bolt. Once you have drill as big as you can without getting into the threads, you can use a pick to chip what is left of the bolt threads away. Once you can get a tap started it is then a matter of carfully and slowly truning the tap in and backing it out little by little to remove the rest of the bolt threads. Don't try and run the tap all the way in right away. Good Luck

As can be clearly seen at the bottom on the cylinder, this is were the cumbustion is leaking into the coolant passages. Every 2.5 DOHC engine with leaking head gaskets leak in this same spot. Should have cleaned the block up a little more for this pic, but you can still see at the bottom of the cylinder were the combustion leak is. Any of the "Updated" OE head gaskets that I have seen fail...........Same Same. This is a 160K mile engine. No piston slap on start up when driven into shop. Definetly hydrocarbons in the cooling system. Very little to no residue in coolant recovery bottle. These hadn't been leaking for very long. I have seen coolant recovery bottles as black a coal inside from head gaskets that had been leaking for a long time. What can't be seen in the pics, and I can't get a picture to show it is..........Were the leak is, the origanal milling marks on the head and the block are worn away. They can be seen all around the rest of the matting surfaces. So, there has to have been movement between the cylinder and gasket and the head and gasket were this wear is occuring. Correct? Question for those smarter than me. (1) What could be the cause of this movement? (2) How can any head gasket be designed to stop this movement. Now the updated gasket.............rather than the origanal designe of one thick layer between to thin layers with a solid fire ring, they are one thick layer with two thin layer on one side one on the other, with out a solid fire ring, and the area that seats to the cylinder is graphite coated. Correct me if I'm wrong......................Multi layers without a solid fire ring would allow for the layers to move aginst each other and maybe not brake the seal at the cylinder and cylinder head. Then wouldn't the movement between the layers allow for wear, then add in the fact that there is not a solid fire ring couldn't a leak develop between these layers? But then there is the graphite coating on the mating surfaces. Woould this be to allow movement at those surfaces without the wear? Engineers?

Ok, In your opinion, which you are entiltled to, the original gaskets failed do to the fault of the vehicle owner or the gasket itself. And any repeat failure, if the problem was not diagnoised and repair performed by Gary Gross, then the failure was either due to the fault of the owner, or the person who repaired the car. Now I understand were you are coming from. Very bold veiw point.

Post #17 is a start.