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2.5L DOHC Head Gasket Failure *PICS*


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109 replies to this topic

#26 RallyKeith

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Posted 30 January 2007 - 07:11 PM

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?



Look here to answer your question:
http://www.ultimates...ead.php?t=41751
There is a mixed view on this board, but I'm of the opinion that you should replace them. In fact there are a few sets on Ebay now, and they are available from many parts stores. My thought is that a part like this wouldn't be available if it was something that didn't neet replacing.

Keith

#27 WJM

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Posted 30 January 2007 - 08:46 PM

I'll chime in on this...

First, as an SOA trained master technician, we have not been taught to replace head bolts unless we see a situation out in the feild that warrants the replacement of them. Otherwise...I've never replaced any. I've done over 20 (that I can count/recall) DOHC HG replacements in the last year, and probably double that many on the SOHC's.


In reference to the DOHC headgaskets...I own a 1996 that until 203,000 miles, was still on the original headgaskets. This one had the CARBON-COMPOSITE gaskets like the EA82 and EJ22's get. I drove it until it could not go 1/4 mile before blwoing coolant everywhere. I replaced the HG's with the new multilayer metals and was fine...until 234k. I have cracked the block, so...in the hot summer days, it will randomly overheat. Drive steady state and its not a problem. Stop and go makes the problem happen. Now that its cold, I can daily drive the car with no issues as long as I mind the coolant temps in traffic...90% of the time there's no problem.
Anyhow, the reason for the problems is first they went cheap and used the composit HG...well, even EJ22's and EJ18's blow them. Add more TQ/HP and less HG area and they'll blow more often. Next, they went witha cheap metal one. No good. The sealing layers were too thin and brittle over time. Now the 11044AA610's are full multi layer metal, SAME as the EJ turbo gaskets (EJ205/207/255/257). Those engines take a TREMENDOUS pounding, and with stock HG's and headbolts with STOCK factory TQ procedures...take 700 wheel HP (EJ257/255) just fine.

Now...onto the SOHC...

These leak externally. While the gasket it better and 99.9% of the time do not develop internal leaks...the gasket is metal at the core, but with a rather cheap-ish sealing surface that will leak externally. The updated gasket does not have this problem. Note-you *CAN* use the 11044AA642 (EJ255/257)gasket in place of the 11044AA632.....BUT SOA will not cover that part under warranty. I would only recommend it under a customer pay (external leak with over 100k miles and SOA warranty/customer satisfaction not being involved) situation.


As for the head bolt TQ procedure...I use the factory one, but on the last step of going 45*....I instead go 90*.


Overall...any EJ engine that was driven while overheating will ensure problems later down the road. Be aware.

#28 mspeters

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Posted 30 January 2007 - 08:58 PM

I believe after seeing just how little support the cylinder has from the rest of the block that vibration is the primary factor in gasket failure. In fact it makes perfect sense that the wear areas are caused by this. Graphite probably works very well as a polishing agent. The cylinders are in effect cantilevered with a different natural frequency than the rest of the head, which would move much less relative to the cylinder.

I cant be the 1st to suggest that they need to support the cyl wall more; if they need to increase H2O pump capacity / cooler thermostat then so be it. This of course is academic.

It would be interesting to see a block with a tounge and groove cut into the cyl face and head to lock it into place... if there is even enough real estate for that.

#29 cookie

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Posted 30 January 2007 - 09:06 PM

It's been years so I may be wrong, but it seems like some VWs had the cyls lock in the head.

#30 Snowman

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Posted 30 January 2007 - 09:25 PM

As far as head bolt replacement, as long as the bolts are not torque-to-yield, the stretching will be minimal as long as the engine is not overheated. For example, I reused the bolts on my mom's DOHC EJ25 because it had never actually gotten hot (I saw black residue in the overflow tank, so I replaced the HGs before they got bad). I also am okay with reusing bolts on EA82 engines that had seen some heat because they're not torqued as tight and probably haven't stretched as much as EJ bolts that saw the same amount of heat. I do think that if you've had the heads off like five times, it's time for new bolts, but as long as they haven't seen any severe conditions, they're fine for one or two reuses.

Of course, that's just my humble opinion.:rolleyes:

#31 nipper

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Posted 30 January 2007 - 09:57 PM

The aluminum in the block is weaker then the bolts, so you have to work awfully hard to stretch them, so you dont need to replace them.
If you want to, DO NOT buy bolts off ebay. There is a lot of counterfit bolts out there that don't meet specs (thank you china).
Also you have to remeber that there is a weird torquing pattern for the heads from subaru. If thats not followed that will give problems.


nipper

#32 RallyKeith

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Posted 30 January 2007 - 11:06 PM

As far as head bolt replacement, as long as the bolts are not torque-to-yield, the stretching will be minimal as long as the engine is not overheated.


See that's just it. Everyone I've talked to has said that based on the torque procedure they are torque to yeild. I don't think I have any new bolts laying around, but I shure would love to measure the ones I took out against some new ones.

The aluminum in the block is weaker then the bolts, so you have to work awfully hard to stretch them, so you dont need to replace them.


The strength comes from the threads, count and pitch. If I remember correctly there is something like an inch of threads. I believe as the block and head expand with heat it makes the connection even stronger.

#33 WJM

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Posted 31 January 2007 - 05:48 AM

The head gasket is tq-to-yeild. thats why the procedure has you doing a rain dance around the engine at one point.

#34 Setright

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Posted 31 January 2007 - 06:47 AM

First of all, I have owned a used EJ22 that blew a headgasket around 120k miles. Blew in the same way as in the pics, only it was just one leak on cylinder three.

They were black. So was the first replacement, which developed the external leak within days.

Silver coloured, multi-layer gaskets solved the problem.



Second: Judging by the number of failed 1.1 bar OE radiator caps that I have seen, I would suggest they are the weak link. The pressure seal fails and the coolant is allowed to escape practically unnoticed, until suddenly one day the temperature needle makes a dash for the red zone.
Observant drivers will stop before they overheat long/hard enough to blow an HG.


SO, if you have any late 90'ies Subaru and haven't relaced the original rad cap yet....get it done !

:)

#35 MDW25gt

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Posted 31 January 2007 - 07:20 AM

This is a great thread. I want to stay plugged into the lates thinking. I replaced my engine 30k miles ago. In 99 LGT. It had 127 miles, but the gasket had been blown for at least 25k miles.

New short block, heads, the works. Used the latest HG. So far so good.

The guy that did the new engine was NOT a Subie dealer. Trained most of the Subie dealer mechanics in Cincinnati though. Very careful about his work. I am please with the results. I hate to think of replacing the HG in the near future.

#36 Petersubaru

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Posted 31 January 2007 - 08:57 AM

what was happening or what did you see, to make you believe that the head gasket was leaking for 25K before repairs were needed...

This is a great thread. I want to stay plugged into the lates thinking. I replaced my engine 30k miles ago. In 99 LGT. It had 127 miles, but the gasket had been blown for at least 25k miles.

New short block, heads, the works. Used the latest HG. So far so good.

The guy that did the new engine was NOT a Subie dealer. Trained most of the Subie dealer mechanics in Cincinnati though. Very careful about his work. I am please with the results. I hate to think of replacing the HG in the near future.



#37 johnceggleston

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Posted 31 January 2007 - 09:38 AM


SO, if you have any late 90'ies Subaru and haven't relaced the original rad cap yet....get it done !

:)


what do you recommend as a replacement? O)EM or is there another brand known to be top quality that would be better than oem (which can fail)? ie: not cheap, maybe racing quality, i don't like wasting money but a 15$ rad cap is more cost effective than a new HG.

i found my 97 obw, 108k, leaking coolant from the cap and replaced it with a cheap generic brand ($7). i wouldn't have found it except i was running the car at idle in the drive way to charge the battery. once it reached operating temperature, (not when cold) the cap started to leak. it was a little difficult to determine the source of the leak.
apparently, i was lucky!!

thanks

#38 RallyKeith

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Posted 31 January 2007 - 10:47 AM

The head gasket is tq-to-yeild. thats why the procedure has you doing a rain dance around the engine at one point.


Yeild is the point at which a metal becomes elastic (stretches) and does not come back to original shape. Using this defenition, yes the gasket is deformed after being torqued, and never goes back. The question is the bolts. Using the argument that SOA never told you to replace them means nothing. Just because they never told you to, doesn't mean that you shouldn't. The fact is that you strech the bolts in the installation process. The real question is if it's to yeild.


I think everyone discussing this topic should read this:

http://www.rv8.ch/ar...051227112926716

It has some really good information.

#39 WAWalker

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Posted 31 January 2007 - 11:00 AM

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.

#40 grossgary

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Posted 31 January 2007 - 11:31 AM

i'd be interested to see some torque values of bolts that have been run for 30k, 50k, 100k too with good headgaskets. be hard to see those kinds of numbers though.

#41 cookie

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Posted 31 January 2007 - 11:41 AM

Subarus are tough to do much testing on for the average guy. It's not like we have a single gasket sticking up on top of the engine. I'd have a hard time blaming the fasters for this, but sometimes a stud kit has fixed a gasket blowing Chevy.

#42 RallyKeith

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Posted 31 January 2007 - 12:36 PM

Subarus are tough to do much testing on for the average guy. It's not like we have a single gasket sticking up on top of the engine. I'd have a hard time blaming the fasters for this, but sometimes a stud kit has fixed a gasket blowing Chevy.


I want to appologize for steering this off course a bit. I don't, nor do I believe anyone else, thinks the bolts have anything to do with the initial failure cause. I was bringing it up as a possible cause for replacement gasket failures. That article I posted talked somewhat about why using a head stud help eliminate the variability of actual applied torque, but it also said that TTY (Torque To Yeild) or TTA (Torque To Angle) solved some of that same issue.

We could debate the issue of re-using head bolts for ever. Unless we do some research or true scientific testing, or ask the engineers in Japan that designed it, we won't know. So I'm going to stop argueing that point and move forward. I appologize.

Keith

#43 nipper

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Posted 31 January 2007 - 02:03 PM

I want to appologize for steering this off course a bit. I don't, nor do I believe anyone else, thinks the bolts have anything to do with the initial failure cause. I was bringing it up as a possible cause for replacement gasket failures. That article I posted talked somewhat about why using a head stud help eliminate the variability of actual applied torque, but it also said that TTY (Torque To Yeild) or TTA (Torque To Angle) solved some of that same issue.

We could debate the issue of re-using head bolts for ever. Unless we do some research or true scientific testing, or ask the engineers in Japan that designed it, we won't know. So I'm going to stop argueing that point and move forward. I appologize.

Keith


I can tell you that used head bolts from an aluminum engine have the same strength as new ones.
We were in a slow period in the metalurgy lab and decided to find out (we were all car guys).
We did a rockwell hardness test and a load test. The threads were in a steel bolt and the threads of both bolts gave within 10% of each other.
The load to failure test was almost the same.
I want to say the bolts were from a honda buut it was years ago.
Sorry i dont have the numbers to show, as it was a "i wonder...." kind of test.

Steel bolts in a steel block should be replaced, but they also blow head gaskets far less.

nipper

#44 WAWalker

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Posted 31 January 2007 - 07:18 PM

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?

#45 MDW25gt

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Posted 31 January 2007 - 07:36 PM

what was happening or what did you see, to make you believe that the head gasket was leaking for 25K before repairs were needed...


Coolent over flow tank filling up after running on highway. Was not until the latest stages that over heating started. I also noticed that after a coolent flush and replace that the problems got worse. Could have been not getting the air all out during refill. But I also suspect the flush used could also have been a contributer. I ran for at least a year after the flush so I dont think the refill was the problem. I think it would have failed in less than a year if that had been the problem.

#46 Tech1967

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Posted 01 February 2007 - 11:29 AM

Bump.:burnout:

#47 WAWalker

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Posted 01 February 2007 - 12:00 PM

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.:)

#48 nipper

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Posted 01 February 2007 - 12:23 PM

http://users.sisna.c...headgasket.html

Just an FYI

For the record, its not just subaru that has this problem. Google Head gasket and you will see gm ford chrysler (lots of neons) toyota etc all have HG issues of some kind. Interestingly its not across the entire product line, only specific engines. If i ever get snowed in one day ill have to see if i can find a common denominator. If i had to guess, i would say its the deck (hybrid open type) design.


nipper

#49 WAWalker

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Posted 01 February 2007 - 12:30 PM

Edited due to total lack of technical content.

#50 Petersubaru

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Posted 01 February 2007 - 12:50 PM

keep the info coming..a very popular topic with over 800hits in 2 days

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.:)






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