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2.5 dohc the engine I love to hate and love again


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17 replies to this topic

#1 Ionlyhave3suubs

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Posted 07 January 2011 - 09:45 PM

Allright, first of all I love my Subarus and all 3 of my Legacy series have had 2.5 engines in them. 3 have been the dohc 2.5d and I also now have a 02 sohc 2.5.

My first legacy (still have, and the one that is giving me a fit) is a 97 obw with AT. Most of my nearly 190k miles I have put on it since I bought it (used in 99) have been relatively trouble free, until recently.

Finally at just a bit under 230k miles the original head gaskets finally gave out. I stopped driving it when that happened. I had just bought my 96 Legacy LSi (knowing it had bad head gaskets) and fixed that along with a few other things. I recently got around to doing the head gaskets on the 97 but I fear I may have skipped an essential step (or so). :banghead:

I did not get the heads professionally checked for warpage. I know the engine and know it was never allowed to get very hot, so I didn't think it was necessary. That is a possible problem.

I used fel-pro gaskets when I did the job. I felt confident these were suitable since I used them on the 96 LSi with no issues, no leaks.

When I re-assembled the heads to the engine block, I left out the step of oiling the head bolts before torquing them.

I used the spray copper gasket sealer on the head gaskets and head and block mating surfaces. I used this also on the 96 LSi and no issues.

All of that being said, the car runs ok and is not overheating. The only symptom of a sealing problem is what appears to be an external coolant leak that appears to be coming from the rear of the passenger side head to block seam (head gasket area). It manifests as a steam that appears to be coming out from the head gasket area.

I am wondering if it is possible to re-torque the head bolts while the engine is still in the car. I know it is tight, the cams have to come off etc., but is it possible?

Is it possible that I could solve the problem by re-torquing the bolts, as in taking the tension off all of the bolts on that side, removing the bolts one at a time, oiling them then putting them back in and torquing them to the proper specs?

The body on the car is pretty good still. A few minor dents and dings but not rusty. The driveline is starting to really concern me though. In parking lots it pops and "crabs" in tight turns. I am suspecting a rear differential and/or a front to rear differential problem. I'm getting to the point that I am getting fed up with working on the 97 so much and wondering if it is worth fixing (or trying to fix). I am just not ready to pull the engine out again to mess with the high mileage engine that may have a failing drivetrain behind it.

I am not interested in doing a 2.2 swap at this time unless someone has a really cheap good one within driving distance to Roanoke, VA.

I would consider building a frankenmotor for this car, but would need a good pair of egr compatible heads from a 2.2. Frankenmotor would need to be a project for later due to funds and the need to get my son's Celica going for him.

Ideas, suggestions, encouragement?
All 3 are welcome.

#2 nipper

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Posted 09 January 2011 - 03:45 PM

Many errors here

1- A machine shop doesnt only check for warpage, it restores the finish on the heads that are so important to sealing properly.

2- ONLY USE OE GASKETS for the HG. Felpro or anyone else is junk as they are do not get the latest updates. I have talked about this adnasium so I wont cover it here, just trust me on it.

3- Not important as it affects torque values.

4- NOTHING is used on any of the sealing surfaces on the HG, on the block or head. That finish is needed for the seal.

#3 nipper

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Posted 09 January 2011 - 04:00 PM

You did everything wrong. Did you read a manual when you did this?

As i say this nicely :eek:

Machine shops check the heads and restores the finish that is needed for sealing. The sealing surface needs to be the proper finish.

At 230K it should have gotten a valve job

Use ONLY OE gaskets as felpro or anyone else will not have the latests desghn. They only make the first gen or if lucky second gen, and have maybe 10 engineers to cover 1000's of vehicals. I worked for an aftermarket mfg, i know how it goes. They wont have the 4,5,6 generation of the gaskets.

Copper sealant on any part destroys the sealing properties of the HG. there is a reason for the finish on the cylinder head. Gaskets do the most sealing on the outer edges and coper or any other thing ruins that seal by filling the surface finish.

YOu should have lubricated the bolts as you may have gotten the wrong torque readings. if the book says oil, then oil. The bolts are reusable.

You do not re-torque modern HG's as that will crush the fixed compression of the HG (which is already ruined).

I am surprised that is the only problem you have. Some time soon you will start having an internal leak.


This is not the engines fault, but yours. You are going to re-do the HG, but i dont know how hard it is get the copper spray off.

http://www.aa1car.co...brary/ic697.htm

http://www.aa1car.co...brary/ar996.htm

#4 Fairtax4me

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Posted 09 January 2011 - 04:04 PM

Where did this thread come from?
We already covered all of this didn't we? :confused:
http://www.ultimates...ad.php?t=119153

#5 nipper

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Posted 09 January 2011 - 04:23 PM

WHen i get bored i go three pages back to look at the threads with 0-3 responses. Though this being jan it shold have been farther back then that.

#6 Ionlyhave3suubs

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Posted 09 January 2011 - 09:02 PM

I have no idea how there is a duplicate of the thread.

To answer your question, Nipper, yes I did read my Haynes manual before and during my H G replacement. Mine is a 1998 copyright that I that I bought shortly after I bought the car. In section 2A-17 in reference to the installation of the H G step 12 it says " Refer to the cylinder head gasket manufacturers instructions and if necessary, apply a thin even coat of the recommended gasket sealant to both sides of the head gasket then lay it in place (see Illustration)."

Since the fel-pro gaskets came with no instructions, I consulted the parts counter guy to see if sealant was necessary. This was when I did my first 2.5d last winter. The parts guy told me that the H G did indeed need the sealant and that the sealant needed to be applied to both sides of the H G and to the block deck and gasket sealing surface of the heads.

Apparently I got bad information from the parts guy. Interestingly enough, the 96 Lsi 2.5d that I did last winter had NO LEAKS after following these directions!;)

Now I find myself replacing the front crank seal AGAIN on the 96 Lsi because the fel-pro piece backed out from its seat:( Removed the fel-pro seal and installed the oem part, also replaced the o-ring and lock-tited the screws on the back.

#7 Fairtax4me

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Posted 09 January 2011 - 09:59 PM

Apparently I got bad information from the parts guy.

:eek: Imagine that!

[/sarcasm]
I've heard that you should use sealer on head gaskets for cast iron head and block engines. I've only done one HG job on a cast iron block and head engine though. Didn't use any sealer, and it worked out fine. At least until it went to the junkyard. :lol:
Never use sealer on aluminum heads though.

#8 nipper

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Posted 09 January 2011 - 10:08 PM

:eek: Imagine that!

[/sarcasm]
I've heard that you should use sealer on head gaskets for cast iron head and block engines. I've only done one HG job on a cast iron block and head engine though. Didn't use any sealer, and it worked out fine. At least until it went to the junkyard. :lol:
Never use sealer on aluminum heads though.


Remeber in the days before the internet everyone knew someone or heard from someone they could do X


:)

#9 nipper

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Posted 09 January 2011 - 10:37 PM

I have no idea how there is a duplicate of the thread.

To answer your question, Nipper, yes I did read my Haynes manual before and during my H G replacement. Mine is a 1998 copyright that I that I bought shortly after I bought the car. In section 2A-17 in reference to the installation of the H G step 12 it says " Refer to the cylinder head gasket manufacturers instructions and if necessary, apply a thin even coat of the recommended gasket sealant to both sides of the head gasket then lay it in place (see Illustration)."

Since the fel-pro gaskets came with no instructions, I consulted the parts counter guy to see if sealant was necessary. This was when I did my first 2.5d last winter. The parts guy told me that the H G did indeed need the sealant and that the sealant needed to be applied to both sides of the H G and to the block deck and gasket sealing surface of the heads.

Apparently I got bad information from the parts guy. Interestingly enough, the 96 Lsi 2.5d that I did last winter had NO LEAKS after following these directions!;)

Now I find myself replacing the front crank seal AGAIN on the 96 Lsi because the fel-pro piece backed out from its seat:( Removed the fel-pro seal and installed the oem part, also replaced the o-ring and lock-tited the screws on the back.



Parts counter guys you don not trust. Some of them are experts who choose not to pull a wrench anymore, others think they know anything, and it is hard to tell them apart.


http://allwheeldrive...lems-explained/

Dont know if this will help

http://home.comcast....eplacement.html


You made me go out in the bitter cold to get my book..

"Clean the gasket mating surfaces..."
"refer to the Cyl Head Gskt Mfg instructions AND IF NECESSARY.. if being the key word.

Modern headgaskets are made of three different metals, two of which seal against pressures of 1500 psi and 1800 degrees. Whoever this guy is doesnt know a thing. I do remeber back in ancient times that there were a few HG that needed sealant only around the water passages.

When in doubt ask a dealer, a real mechanic, or call the parts mfg hotline.
You may have gotten lucky the first time.

But in the last 20 years I have not seen any headgasket that has used any goo between the HG and the parts. I have however stood at a counter and heard a lot of bad information from a counter. A lot of counter people hear the word gasket and think sealant.

#10 Ionlyhave3suubs

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Posted 10 January 2011 - 12:24 AM

The majority of my engine building experience comes from iron head, iron block domestic v8s. I was taught by a veteran mechanic that had owned and managed his own shop for over 20 years. He taught me (on the v8s) to use a sealer (different type) on the V8s. I always did, and always with positive result. That was about 20 years ago.

Different engines, different techniques. I've used Fel-pro gaskets for years on domestic applications, also with positive results.

Always a learning process.

I chose Fel-pro due to my years of positive results with their products for domestic applications and the fact that they offer kits. The subaru dealer, at least the one near me does not offer a kit and the parts individually are much more expensive. I see now that the head gasket is something that has to come from the dealer. I wonder though I have also seen another brand held in high regard, Cometic I believe. Are they a premium gasket, or just another aftermarket company? Just curious.

As of now my intention ids to get Subaru brand gaskets. I've noticed also beck-arnley gaskets being advertised as if they are oem on the internet. Is that just an advertising scheme?

#11 mdjdc

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Posted 10 January 2011 - 07:09 AM

Listen to these guys, they know what they are talking about. I too have tried aftermarket HG's and I had to redo the jobs. That sucks and is a real time waster. I also recommend using only OEM for the cam and valve cover seals. I have used aftermarket on these and they started leaking in fairly short order. I hate having to redo a job.

#12 nipper

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Posted 10 January 2011 - 10:53 AM

Now you are in trouble, you forced me to use spell check.

Ok i will repeat myself, then move on to another thread. I am 47 and have been pulling a wrench since I was 7. I have a degree in automotive engineering so I do have a little knowledge of what I am talking about, just a bit ;).

I have worked on one, two, three, four (never a 5 darn it) six, eight (always wanted to do a 12 and a rotary), Diesels LP Hydrogen and Gasoline. I have seen many different types of materials for gaskets and engines over time.

I have been trained and taught that with every part that is known for being weak, you always check with the mfg of the part, never the counter guy, to see if anything has changed.

I worked for an Aftermarkets parts mfg who sold sensors, ignition parts and gasket sets.

They did make some of their own parts. Other parts they got from OE suppliers. The parts from OE suppliers had been locked in (meaning the parts had not changed in X years). There was a 3-5 window depending upon the part that the OE supplier could not sell to a aftermarket parts mfg, unless the part is used unchanged.

Where the Aftermarket could not get the OE part supplier, they either had to reverse engineer it or find someone who is already making it to sell to them. When they buy them from someone else they just make sure that dimensionally (and sometimes the materials) are the same and nothing else. They buy on certs (documentation).

With head gaskets and more critical parts especially from 1995 to present, they are moving targets. As emissions get tougher, the HP race goes on, and the demand for higher MPG, HG's have been critically tortured on the road. Every MFG has at least one engine with HG issues.

HG's cannot be life tested in today’s world. This is why auto mfg's push back when they have a short timeline on a required emissions or MPG increase. HG's to a degree can be tested in the lab and on the puter, but do need real world testing. Ping may not show up in the lab but will on the road (largest cause of HG failure, you don't hear this ping). Failures due to time, leaks, etc.

Subaru does not have a lot of test mules for their engines (a test mule is an engine put into a vehicle it is not destined for to get miles on it). Today’s cars due to being overbuilt and new oils and fuels can last with no maint to 160,000 miles. The head gasket is the weakest part of that link. When you aim to build to the warranty you usual add 25 to 50% of that number, Subaru aims for the higher. That usually covers all the variables.

When you test a HG on the road, the car has to be fully equipped for data. All points recorded. When it fails it goes into a lab, not a shop to be torn down. The engine is removed and all mounting surfaces examined and the head gasket examined in painful detail if need be. Once the issue is found, you research the possible fixes, have the part made in a run of anywhere from 10 to 100. Then you go back to the engine test in the lab, then the road test. If it fails the entire process starts all over again. That is why it took up to ten years for a new engine to come out. Now with some mfgs with failing head gaskets they are under the gun to fix the problem as soon as they start hearing about it from the dealer’s data. Then they have to start examining the failures. If they are similar it is a blessing, if they are different then it is going to take time. With HG's it was not just one attempted fix, it was (3 with sooby?), then they got the internal one fixed and made an external one.

I personally think they redesigned the 2.5 this year to get away from any chance of abnormal head gasket failure.

Now as OE changes the HG design, they scarp the existing ones after a test production run. This is just one mfg with one engine at 50,000 copies a year (just to snag a number).

Let’s call them company X who sells at a parts store (As this is not just felpro). Company x makes # of head gaskets based on sales projections of failures. They do not recall parts when the mfg goes from HG1 to HG2 as they may not even know about it. It takes time and money to retool, and sometimes they depend upon the supplier to tell them there is a change. Then in 6 months later OE develops HG2, then a year later HG3. X is quite possibly on HG1 since OE is not obligated to tell anyone anything. OE will have anywhere from 1 engineer to the entire Engine Team trying to solve a HG engineering issue. In Subaru’s case they only built the 2.5, 2.3, turbo and diesel) and only had one engine with an issue. In a larger mfg every engine will have a design team assigned to it.

Company X does not have anywhere near those kinds of resources. They have to make parts for 1000's of engines and n one has the 1000's of engines lying around for testing (or the required simulations). The only way they will find out about a lot of failures is either a spike in sales (and that doesn’t get past sales sometimes), or if they themselves get returns. Usually when someone blows a HG they go to OE or aftermarket. If they go to OE they throw a huge fit (rightly so) if it fails again. If it fails again with aftermarket people either walk away or go back to OE parts.

With majorly important parts (there aren’t many in an engine) I will always go with OE.


When engines were big lazy cast iron blocks, I would always buy felpro. When engines went to aluminum started buying oe. As engines got lighter and higher rpm I switched to only OE after I saw a pattern of HG failures with increased power demands on all mfgs.

There are very few parts I will buy OE and they vary from Mfgs to MFG. On Subaru’s I would buy OE for HG, Thermostat, Valve cover gaskets, spark plug bucket gaskets, front O2 sensor and high quality OE preferred plug wires.

I am always skeptical when someone comes out with major high stressed part that is not OE that solves any problem with the part as they just do not have the resources to check it.

I won’t even mention the decision to rebuild the HG on an engine with such high mileage on it. I would have just gotten a used engine, but that’s another discussion.

Good luck.

Oh and a PS... After a car gets to be X years old (maybe ten maybe 15 depending upon the part) they do not bother updating that part anymore. It just isnt cost effective as the car ages out of the market, and they may not know a 97-98-99 parts are all different where on paper they are the same.

Edited by nipper, 10 January 2011 - 11:00 AM.


#13 Ionlyhave3suubs

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Posted 10 January 2011 - 07:50 PM

Thank you for your thorough explanation of the OEM vs. aftermarket r&d of gaskets and other parts. Please don't think I was doubting your advice, I was just explaining how I came to the decision to go with the brand I did in the first place. As far as the decision to re-gasket the 2.5, I have been looking for a lower mileage 2.5d near me but the only ones available in my area that I have found were out of my price range and/or were "overheating" aka blown head gasket. My financial resources are quite limited at the moment as a are a lot of peoples, so doing the HG repair which I have already successfully done on another almost identical engine seemed the way to get the car going again to last at least one more winter. I opted to do this car first as it has slightly better ground clearance which helped significantly last winter when we got some deep snow. I also already have chains that fit the outback tire size. Water under the bridge now, It didn't work out, so I fixed the almost Valdez size oil leak:eek: on the LSi and I'm good to go, with just a little less ground clearance.:rolleyes:

I haven't decided for sure what to do with the outback as of now as my resources to buy parts for now are pretty much depleted, and the HG is not the only problem, it has developed a significant torque bind as well.

As I stated in my previous post, I do intend to buy Subaru brand HGs next time I need to do a HG replacement.

When I get the funds up and If I decide to fix it, I will probably go the 2.2 conversion route, providing I can find a decent package deal on the other driveline components I'll need to fix the torque bind problem.

Nipper, if I got you riled, sorry, I didn't mean to.

#14 mdjdc

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Posted 11 January 2011 - 06:54 AM

Hey, you aren't that far away and tohe car should be good on the highway. If you want to get the tranny done in one day, come to Richmond and we can do the job together. Just get the Duty C solenoid and I can fix the drums for you. Feed me or something.

Just an offer to another subie guy.

#15 Ionlyhave3suubs

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Posted 12 January 2011 - 09:15 PM

mdjdc I really appreciate the offer. Right now I am not in a financial position to buy any more parts and I am working a lot of OT to try to get caught up on some financial responsibilities.

I am not sure if I'm going to be able to afford to fix the outback anytime soon (if at all).

I have gotten my Lsi street legal again and mechanically sound, so I am not in a pinch for a car to drive.

Thanks again

#16 mdjdc

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Posted 13 January 2011 - 08:18 AM

Perhaps, when it warms up a bit. We might even possibly find a used solenoid at a local JY here in richmond. If you decide to sell the car, please let me know, I have several people looking for one right now and nothing on the block.

#17 Ionlyhave3suubs

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Posted 17 January 2011 - 08:05 PM

Hmm, I was browsing through frankenmotor information on this message board and ran across a link to Nasioc, referencing the drilled headgasket, and behold the gasket being referenced has been sprayed with the same copper coating that I used.

I wonder how many other people are using this unnecessary, potentially leak causing coating?


http://forums.nasioc...d.php?t=1107352

http://www.ultimates...kenmotor&page=2

Edited by Ionlyhave3suubs, 17 January 2011 - 08:08 PM.
add second link


#18 Fairtax4me

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Posted 18 January 2011 - 01:28 AM

It's actually a very common practice. Some engines it works out fine, others not so fine. Personally I've seen it cause more problems than it prevents. Especially in the case of the new style MLS gaskets, which already have a thin coating of sealer on them.

From Cometic's FAQ section:

Why does Cometic recommend MLS gaskets to be installed dry?
Cometic Multi-Layer Steel (MLS) head gaskets go on dry because they are coated with a sealant. Each MLS head gasket is coated with a .001" thick viton rubber that is bonded to the outer stainless steel layers. Adding an additional sealer can hinder the performance of an MLS head gasket.



More information about Viton based compounds can be found on DuPonts website.


Another problem... Dust.
Dust will not stick to a dry gasket. It will stick, and glue itself, to a gasket covered in wet spray on sealer. Now your average household dust, in small quantities, isn't a big deal. But if you're doing this in a shop or outside somewhere and you have pollen or other "large" (in comparison) particles of various types of dust flying around in the air... you can see where this is going. Dust gets between the gasket and the sealing surface and creates a pocket where air can be trapped, air expands and contracts with heat cycling. If the pocket is near the combustion chamber seal ring, it will eventually open a path for combustion gases to get under the gasket, and after that it's all over. Sealer gets burned out, gasket gets burned out, leak begins.




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