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How to positively Identify 2.5 Engine in 99 Outback?


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35 replies to this topic

#26 WAWalker

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Posted 26 January 2007 - 11:54 AM

Oh, and as you can see from the first chart, the 8 bolt bell housings started in '98.
The bolt patterns are all the same but there are differences between the MT and AT I believe due to different starters. On a MT two of the bell houseing bolts/studs hold the starter on. Were as on a AT one bell houseing bolt/stud and one stud installed in the transmission houseing holds the starter.

#27 OB99W

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Posted 26 January 2007 - 03:30 PM

There are more differences than just the 8 bolt bell housing. That block is rear thrust vs. center thrust in the 4 bolt.

There are also about 6 different types of pistons used between late '95 and '99 in both the DOHC and SOHC. (Don't quote me on "6"...but I know it's more than 2 or 3. We have different shelves for each style.)

Between '90 and '99 there were only 5 different blocks, if you don't count late Loyales:
EJ22
EJ22 turbo
EJ18
EJ25 DOHC center thrust
EJ25 SOHC rear thrust



Posted Image

This is straight from SOA TSB. This is probably wear the idea of a "Hybrid" 2.5L came from. Unlike the new bare boneshort blocks that could be purcased through the dealers, these rebuilt short blocks come with oil pan, water pump, thermostate and houseing, and oil pump, thus making them "Hybrids".?

Anywhoo..................There is the application chart for your '97-'99 DOHC 2.5L engines.

Then in '99 production of the SOHC engines started. I still don't have all the specifics on what got the 2.2L SOHC and what got the 2.5L SOHC.

Thanks, Emily (ccrinc) and WAWalker (the SOA info is especially interesting). This seems to support the contention that there are "later" blocks (so-called "8-bolt", really 6-bolt 2-stud, with rear thrust) paired with "earlier" heads (DOHC), as my own MY99 OB came set up that way from the factory. The pistons would have to be chosen to not interfere, provide correct compression ratio, etc. for any particular configuration. Apparently 97-99 was a transitional period in the EJ25, Phase-I versus Phase-II.

Here's what "hybrid" may mean in the context we're discussing, from: http://www.answers.com/hybrid&r=67
**hy·brid - n. Something of mixed origin or composition.
--also--
**Refers to a myriad of products that combine two or more different technologies.

Whatever "hybrid" specifically means to SOA, thanks to everyone who helped clarify that there are indeed EJ25 versions that combine DOHC heads with the block later used on the SOHC engine. So now I'm back to my previous question -- are there any statistics (or opinions :) ) as to how the HGs hold up on the "mixed heritage" engines?

#28 WAWalker

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Posted 26 January 2007 - 05:01 PM

Thanks, Emily (ccrinc) and WAWalker (the SOA info is especially interesting). This seems to support the contention that there are "later" blocks (so-called "8-bolt", really 6-bolt 2-stud, with rear thrust) paired with "earlier" heads (DOHC), as my own MY99 OB came set up that way from the factory. The pistons would have to be chosen to not interfere, provide correct compression ratio, etc. for any particular configuration. Apparently 97-99 was a transitional period in the EJ25, Phase-I versus Phase-II.

Here's what "hybrid" may mean in the context we're discussing, from: http://www.answers.com/hybrid&r=67
**hy·brid - n. Something of mixed origin or composition.
--also--
**Refers to a myriad of products that combine two or more different technologies.

Whatever "hybrid" specifically means to SOA, thanks to everyone who helped clarify that there are indeed EJ25 versions that combine DOHC heads with the block later used on the SOHC engine. So now I'm back to my previous question -- are there any statistics (or opinions :) ) as to how the HGs hold up on the "mixed heritage" engines?



IMO
I wouldn't say that '97-'99 was really transition years. More like a good idea gone bad. '96 was a transition year from the 2.2 to a larger more powerful engine, the 2.5. More dispaclement and DOHC's in a search for more power. Immediatly changes were made for the 97MY. Shorter pinstion skirts and solid lifters, again in the hunt for more power. The shortened pistion skirts resulted in pistion slap that cost SOA a lot of money. The head gasket design was also different between '96 and '97. This is conjunction with the larger bore resulted in head gasket failures, that also cost SOA money. I think these issue were probalbly a huge part of reason for another engine design. Historicaly, when Subaru has built a good reliable engine, they have used it for many years. JMO

I think everyone is overthinking the "Hybrid" thing. The Hybrid engines that subaru dealers sell are Short Blocks, rebuilt by Cummins for SOA. They were production blocks for the '97-'99 DOHC. They are not nessasarly a mix of the best of two worlds. They are rebuilt lower ends period. You buy one and either use your old cylinder heads as is, have them rebuilt, or buy new, and install them on the rebuilt block. The result being a rebuilt engine that either has the 4 or 8 bolt bell houseing depending on what year of car your putting it in.

As I said I don't have all the specifics on the blocks used for the SOHC engines. I don't know that they are the same as the '98-'99 8 hole rear thrust block, or if there were maybe some other changes. I do know that the dealer here needed a SOHC core to send back to SOA at one point in time and had to have a '00 or newer, a '98-'99 8 hole block wouldn't do. I don't know why, and didn't ask, just sold them a block.

As far as the head gaskets.........................This has been pretty well documented. The DOHC engines had a internal combustion leak into the cooling system. The SOHC engines have an external head gasket leak, primaraly drivers side bottom rear of cylinder head.

#29 OB99W

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Posted 26 January 2007 - 05:22 PM

[...]
As I said I don't have all the specifics on the blocks used for the SOHC engines. I don't know that they are the same as the '98-'99 8 hole rear thrust block, or if there were maybe some other changes. I do know that the dealer here needed a SOHC core to send back to SOA at one point in time and had to have a '00 or newer, a '98-'99 8 hole block wouldn't do. I don't know why, and didn't ask, just sold them a block.
[...]

Thanks for the additional info. I don't have any "specifics" either, and some of this discussion seems to have become one of semantics, so I think I'll stop trying to get any further details.

Of course, if anyone knows for sure ... ;)

#30 WAWalker

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Posted 26 January 2007 - 06:06 PM

Maybe I not sure exactly what it you are trying to find out. And I'm not sure what you mean by "mixed heritage" engines.

#31 OB99W

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Posted 26 January 2007 - 06:42 PM

Maybe I not sure exactly what it you are trying to find out.

By now I'm probably boring everyone else, so this will be my last attempt. We know that the early Phase-I/DOHC 2.5L engines developed internal leaks when the HGs went. We also know that the later Phase-II/SOHC ones typically leak externally when their HGs go. I'm trying to get a sense of the situation for the 2.5 engines which are still DOHC, but use the later block (rear thrust and whatever other changes were made). Do such engines only exhibit the internal leak, the external one, or are they possibly more prone to both (or neither ;) )? This is hardly a critical issue to me, so if it's an unknown, we can certainly drop the topic.


And I'm not sure what you mean by "mixed heritage" engines.

That was my attempt at avoiding the term "hybrid". :)

#32 WAWalker

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Posted 26 January 2007 - 07:38 PM

By now I'm probably boring everyone else, so this will be my last attempt. We know that the early Phase-I/DOHC 2.5L engines developed internal leaks when the HGs went. We also know that the later Phase-II/SOHC ones typically leak externally when their HGs go. I'm trying to get a sense of the situation for the 2.5 engines which are still DOHC, but use the later block (rear thrust and whatever other changes were made). Do such engines only exhibit the internal leak, the external one, or are they possibly more prone to both (or neither ;) )? This is hardly a critical issue to me, so if it's an unknown, we can certainly drop the topic.


OK

The difference in the "Phase-I/DOHC 2.5" engine block w/ 4 holes and center thrust, and the "Phase-II/DOHC 2.5" engine block w/ 8 holes and rear thrust, has no bearing on the head gasket issue.

All DOHC engines have the internal leak. Have never seen one leak externally.

I my experiance, since I've started tracking useage of parts I've done 30+ head gasket jobs in the last 4 years. Looks like most have been '97's but there has been plenty '98's and 9's in there too. Then you have to consider that due to age there are probably more '97's than '98's hitting the failure window milage wise, more '98's than '99's.................Did a '98 Monday, have a '99 comeing next Monday, so they are catching up.


The SOHC engines all have the external leak. The only one I've seen that had an internal leak, someone had already replaced head gaskets on once. Don't know what they did wrong, I did not tear down engine. I was able to help customer get the dealer to fix under warranty.


Have not come to a conclusion as to what is causeing the external leak and SOA isn't telling cause they aparently don't know. Their campain letter said the problem was fixed mid 2002, but there are 2003's and 4's with same problem. My best geuss is the head gasket itself, they are a joke.

So No it dosen't matter what engine block you run, when you look at the cylinders of one with the heads off they are all the same. The ones with problems that is. If they don't have a problem there is no reason to pull the heads and look, is there?

#33 WAWalker

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Posted 26 January 2007 - 07:39 PM

Buy the way, I think this is a very good topic. Not boring at all.

#34 Distance Commuter

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Posted 26 January 2007 - 10:34 PM

Buy the way, I think this is a very good topic. Not boring at all.


I agree. But then sometimes people tell me I'm boring them, so what do I know?...

#35 johnceggleston

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Posted 27 January 2007 - 07:25 AM

i'd be interested to know if there is a 'mileage widow' associated with the 30+ heads gaskets you've done? i have a 97 obw with 110k miles (and piston slap) and i'm wondering if i have dodged this bullet or still waiting.

OK

The difference in the "Phase-I/DOHC 2.5" engine block w/ 4 holes and center thrust, and the "Phase-II/DOHC 2.5" engine block w/ 8 holes and rear thrust, has no bearing on the head gasket issue.

All DOHC engines have the internal leak. Have never seen one leak externally.

I my experiance, since I've started tracking useage of parts I've done 30+ head gasket jobs in the last 4 years. Looks like most have been '97's but there has been plenty '98's and 9's in there too. Then you have to consider that due to age there are probably more '97's than '98's hitting the failure window milage wise, more '98's than '99's.................Did a '98 Monday, have a '99 comeing next Monday, so they are catching up.


The SOHC engines all have the external leak. The only one I've seen that had an internal leak, someone had already replaced head gaskets on once. Don't know what they did wrong, I did not tear down engine. I was able to help customer get the dealer to fix under warranty.


Have not come to a conclusion as to what is causeing the external leak and SOA isn't telling cause they aparently don't know. Their campain letter said the problem was fixed mid 2002, but there are 2003's and 4's with same problem. My best geuss is the head gasket itself, they are a joke.

So No it dosen't matter what engine block you run, when you look at the cylinders of one with the heads off they are all the same. The ones with problems that is. If they don't have a problem there is no reason to pull the heads and look, is there?



#36 WAWalker

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Posted 27 January 2007 - 08:36 PM

i'd be interested to know if there is a 'mileage widow' associated with the 30+ heads gaskets you've done? i have a 97 obw with 110k miles (and piston slap) and i'm wondering if i have dodged this bullet or still waiting.


I have seen them go as soon as 88k and as long as 189k. Most are very close to the 100k mark.

I personaly don't think there is any dodging of this problem, if you plan to keep one of these cars for a long time, I think you should plan on replacing head gaskets.




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