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dammit dammit dammit...new 2.5 HG blew


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I picked up a '96 OBW (auto, 156k miles) with a blown EJ25. Pulled it apart, ground the valves, and swapped in a new HG etc. Been driving it for the last three months. Yesterday it was hot here. All the sudden the AC stopped working. I looked at the temp gauge and saw the needle deep into the H zone...like pegged, with the needle wrapped around the stop.:eek:

 

Oh, and I was 50 miles from home.

 

It took 3 hours to get back, stopping every couple of miles to let it cool off so I could toss more water in. Typical scenario --big spash out of the radiator fill on start-up, then bubble, bubble, bubble out of the bleed hole.

 

There was no evidence of cracks in the head and the block surfaces cleaned up just fine. I'm now considering whether to swap in a 2.2 or redo the 2.5, with a trip to the machine shop for warp & crack testing. I'm leaning toward the 2.2 swap, but have some questions that are answered in many different ways all over this forum. I thought I'd ask here one more time:

 

* 2.5 (DOHC) & 2.2 exhaust manifolds appear to be different. How far back do I have to replace if I go 2.2?

 

* 2.5 & 2.2, being different displacement, ought to have different fuel requirements. Must I swap out the wiring & brain from 2.5 to 2.2?

 

* I'm not interested in go-fast engines. Slow and bulletproof is what I'm all about. Which 2.2 is the one to go for (assuming the weight of opinion here doesn't go to fixing the 2.5)?

 

There is nothing worse than having to do something twice...

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* 2.5 (DOHC) & 2.2 exhaust manifolds appear to be different. How far back do I have to replace if I go 2.2?

 

If you use a '95 2.2, that has a 2-port head which will bolt up fine to your 2.5 exhaust manifold.

 

* 2.5 & 2.2, being different displacement, ought to have different fuel requirements. Must I swap out the wiring & brain from 2.5 to 2.2?

 

No, you do not have to swap out the wiring and brain. Basically, remember that an engine takes 14.7 parts air to one part gasoline... a smaller displacement engine is the equivalent of a larger displacement engine at part throttle; it will draw less air in, but the MAF will tell the computer supply a porportionally smaller amount of gas. Also, the oxygen sensor monitors the fuel mixture when the car is running closed loop and will adjust the fuel maps as needed.

 

 

* I'm not interested in go-fast engines. Slow and bulletproof is what I'm all about. Which 2.2 is the one to go for (assuming the weight of opinion here doesn't go to fixing the 2.5)?

 

'95 and '96s are non interference, so that adds another layer of bulletproofness (is that a word.?) On the other hand, used '95 engines are getting kind of old.

 

 

 

Good luck,

Nathan

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I picked up a '96 OBW (auto, 156k miles) with a blown EJ25. Pulled it apart, ground the valves, and swapped in a new HG etc. Been driving it for the last three months. Yesterday it was hot here. All the sudden the AC stopped working. I looked at the temp gauge and saw the needle deep into the H zone...like pegged, with the needle wrapped around the stop.:eek:

 

Oh, and I was 50 miles from home.

 

It took 3 hours to get back, stopping every couple of miles to let it cool off so I could toss more water in. Typical scenario --big spash out of the radiator fill on start-up, then bubble, bubble, bubble out of the bleed hole.

 

There was no evidence of cracks in the head and the block surfaces cleaned up just fine. I'm now considering whether to swap in a 2.2 or redo the 2.5, with a trip to the machine shop for warp & crack testing. I'm leaning toward the 2.2 swap, but have some questions that are answered in many different ways all over this forum. I thought I'd ask here one more time:

 

* 2.5 (DOHC) & 2.2 exhaust manifolds appear to be different. How far back do I have to replace if I go 2.2?

 

* 2.5 & 2.2, being different displacement, ought to have different fuel requirements. Must I swap out the wiring & brain from 2.5 to 2.2?

 

* I'm not interested in go-fast engines. Slow and bulletproof is what I'm all about. Which 2.2 is the one to go for (assuming the weight of opinion here doesn't go to fixing the 2.5)?

 

There is nothing worse than having to do something twice...

 

DO a swap. Its a tough thing to by any aluminum engine with bad HG because you dont know how cooked the engine was. Assuming you used OE replacement parts, odds are the engine was cooked and one of the cyinder sleeves shifted.

 

nipper

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a 2.2 computer would not fire my 2.5 when i tried it.

 

that's not normal and will only confuse the original poster. he's wanting to put a 2.2 in a 2.5, the wiring and ECU will not be an issue. drop in an EJ22 and it will fire...assuming everything is working properly.

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on the EJ25, did you use Subaru headgaskets and did you replace both sides? were the heads checked and milled?

Yes and yes and yes (I checked with my own guages) and no. This was the third one of these I had done. The other two worked out just fine by swapping out the gaskets. I was floored when this one bit me in the rump roast.

 

grossgary, little chance of confusion on that point. Everybody so far has clarified what I already gleaned from the site. Now if I could just find a freakin' wrecking yard in southern MD. They're everywhere in Oregon...

 

Cheers,

Q

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i always mill the heads, it's not that expensive and worth the increased success rate...particularly on that motor. might be worth having the head checked. if it checks out bad but isn't out of tolerance for milling this engine may be fine.

 

grossgary, little chance of confusion on that point. Everybody so far has clarified what I already gleaned from the site.
his statement inferred that 2.2 and 2.5 stuff wasn't interchangeable and that's not true, so i wanted to clarify that before anyone started asking questions.
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Yes and yes and yes (I checked with my own guages) and no. This was the third one of these I had done. The other two worked out just fine by swapping out the gaskets. I was floored when this one bit me in the rump roast.

 

grossgary, little chance of confusion on that point. Everybody so far has clarified what I already gleaned from the site. Now if I could just find a freakin' wrecking yard in southern MD. They're everywhere in Oregon...

 

Cheers,

Q

 

There in lies the failure. YOU ALWAYS have to have the heads sent out to a shop to at least be checked for flatness (even more important with aluminum heads). Unless you have the proper equipment, its hard to do at your workbench.

 

You should consider yourself lucky that the other two worked, not that this one didnt.

 

Since you never had them checked, i wouldgo ahead and send them to a shop and have them checked. if they are warped, thats why the HG failed. Have them machined and do it again and you should be fine.

 

nipper

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Hi. My name is Shannon Honaker. And I too will put testimony to the reliabilty of the ej22 as being one fine peice of aluminum.

 

I will also say that I might be able to find you an ej22 with the egr system in southwestern Va if yo don't have any luck up there...

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There in lies the failure. YOU ALWAYS have to have the heads sent out to a shop to at least be checked for flatness (even more important with aluminum heads). Unless you have the proper equipment, its hard to do at your workbench.

 

You should consider yourself lucky that the other two worked, not that this one didnt.

 

Since you never had them checked, i wouldgo ahead and send them to a shop and have them checked. if they are warped, thats why the HG failed. Have them machined and do it again and you should be fine.

 

nipper

Thanks nipper.

Like I said, I've got the tools and checked the heads. They were flat. I don't have the equipment to test for cracks, but from what I've heard they usually don't crack in a small way. Anyway, for the hassle of pulling them off again, I think I'll just go with the 2.2.

 

Speaking of which, 86BRATMAN, what kind of leads can you give me? Things aren't looking good so far on the 2.2.

 

Hold on! Brandywine Auto says they've got a '95 2.2 out of a Legacy. 100k on the clock & 180-190 compression for $500. Sounds like we might have a winner here.

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Here's the trick question for you Subi masters: how can a head gasket be blown one day to the point that you can't drive it more than a few miles before it blows all of the water out of the radiator, and the next day you can drive it 30 miles down the freeway without it consuming a drop?

 

I loaded up three gallons of water and hit the road, expecting to have to use all the water because that's about how much I used the day before over a similar distance. But the car didn't show the least sign of getting hot. The radiator was up to the full mark before I started the engine for the trip and it was still there hours after I completed the journey. I let the engine cool completely before opening it, but I swear the coolant level hadn't dropped a millimeter.

 

Even though it's a Subi, I'm not trusting this thing. But what the hell? In my experience, blown head gaskets are blown; they don't come and go. Any thoughts? Speculation? Wild ideas about magical Subi fairies doing in-situ repairs? I'm stumped.:confused:

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there are explanations posted on here, but it's quite common for subaru head gaskets to do that. they don't really "blow" in the typical sense, they are really minor leaks compared to a fully "blown" head gasket. what you're experiencing is not weird or abnormal, it's typical EJ headgasket stuff. nipper said it best, that you got away without milling it the first two times was fortunate. use subaru gaskets, have the heads milled and you're likely to have the good results everyone else has. also..if you've done it twice before, but don't still own the cars, there's no telling they really held for 100,000 miles like they should if done properly, so those "successes" are really anecdotal at best.

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I'm not sure why I keep saying that I've got gauges to test for flatness but some folks keep saying that one must have a machine shop do the testing and mill heads that didn't need it. Must be a Subi-master thing.:lol:

 

We had the last car for three years. I'm pretty sure that's past the point where a reasonable person needs to be concerned about whether or not the repair was done adequately. Even complete disassembly, restoration of the block and heads back to factory-original specs wouldn't stop lightening from striking, I think. But whatever... The fact is, these heads were dead-nuts on and there were no apparent cracks. Which makes me lean toward the alternate hypothesis offered: the PO overheated the block enough to tweak it somehow. But we'll never know, cuz it's going to get turned in as a core.

 

So, since "blown hg" is apparently not a term of art on this forum, lemme see if I got this straight: Subi heads develop breaches in the head gasket material through which combustion gases pass freely, resulting in a repeated complete loss of coolant and overheat condition. This pattern can repeat for an entire afternoon and evening while the owner struggles to get home from a long distance away. Upon arrival home and a several hours' long cooling off period, the owner refills the radiator with water and leaves the car until the next day. The following day, the owner starts the car and drives for 30 miles @ 55-65mph, but the void in the head gasket from the previous day has since resealed itself to the point that the engine does not consume any measurable quantity of water. And this is a normal thing.

 

That is some freaky Subi mojo.

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I'm not sure why I keep saying that I've got gauges to test for flatness but some folks keep saying that one must have a machine shop do the testing and mill heads that didn't need it. Must be a Subi-master thing.:lol:

 

We had the last car for three years. I'm pretty sure that's past the point where a reasonable person needs to be concerned about whether or not the repair was done adequately. Even complete disassembly, restoration of the block and heads back to factory-original specs wouldn't stop lightening from striking, I think. But whatever... The fact is, these heads were dead-nuts on and there were no apparent cracks. Which makes me lean toward the alternate hypothesis offered: the PO overheated the block enough to tweak it somehow. But we'll never know, cuz it's going to get turned in as a core.

 

So, since "blown hg" is apparently not a term of art on this forum, lemme see if I got this straight: Subi heads develop breaches in the head gasket material through which combustion gases pass freely, resulting in a repeated complete loss of coolant and overheat condition. This pattern can repeat for an entire afternoon and evening while the owner struggles to get home from a long distance away. Upon arrival home and a several hours' long cooling off period, the owner refills the radiator with water and leaves the car until the next day. The following day, the owner starts the car and drives for 30 miles @ 55-65mph, but the void in the head gasket from the previous day has since resealed itself to the point that the engine does not consume any measurable quantity of water. And this is a normal thing.

 

That is some freaky Subi mojo.

 

SO if you have flatness gauges that can read in the 1000's and a gauge block then your right. Also the surface finish is critical, and that you can not check on the bench, as its an extreemly fine number. Surface finish is almost more important then flatness.

 

Google "why head gaskets fail" for more info

 

 

i am unsubscribing from this thread since it seems to be getting no where.

 

nipper

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Ah, so the presumption was that I was claiming to check for flatness, do a valve job, etc., but didn't actually have the equipment to do it. That would explain some of the replies...

 

Toodles

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i didn't know how long you had those cars, just making an observation. you only had one for a long time, mileage is more important than time and one or two is still anecdotal at best. i'm not saying it won't work...as a matter of fact it will. not trying to poke you, only suggesting that percentages and mileage is much better if it's machined..like nipper said, for flatness and finish. it's not about "right or wrong" so much as percentages. i like a high percentage success rate and many on this board have a %100 success rate on a lot of headgaskets, not just a few.

 

resulting in a repeated complete loss of coolant

 

there's your mistake and the cause of your confusion, that's not what happens. like i said, there are threads discussing the failure mode and how it works. a complete loss of coolant isn't the case, as is the case in other types of head gasket failures. it's more about pockets of air in the wrong place. if the technicalities interest you or you don't believe what you read here, then search this forum or the internet for subaru specific info. then read up on fluid flow, pumps, cavitation and all that fancy jazz and it'll make more sense. i'm not an expert so i won't try to describe "exactly" how it happens, but the information is out there. in a similar way, some systems will overheat, if when filled, they do not have all air pockets out of them...they overheat for the same reasons. same failure mode, but different causes.... this principle isn't "subaru-specific". if you run any engine with underfilled amounts of coolant and see how they respond, some will do the same exact thing...depending how the coolant settles, circulates and where the air pockets end up.

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