Grinding the head

[Hank Roberts]

... I've never seen the exhaust cracks on single port, non-turbo....

 

Hm. This engine is SPFI, non-turbo. What would crack this?

 

Would cracked heads off a turbo be reused on a non-turbo rebuild?

I note the rebuilder says they put all new heads on turbo engines.

 

I bought this from the rebuilder (off the shelf, to save 2 weeks vs. getting my own engine back from them rebuilt) (what a mistake that was).

 

That was two years ago: this one has leaked -- three times: at first install; again at 1 year/maybe 1000 miles; now again after another year/800 miles or so.

 

The local mechanic doesn't want to do as little as they'll allow for repair.

 

Maybe just have to return the engine to the rebuilder. It's got about ten months left on the warranty.

[azsubaru]

I've never seen the exhaust cracks on single port, non-turbo

 

I've got two non turbo EA82 Heads with cracks in the exhaust ports of number 1 cylinder.

[Hank Roberts]

I've got two non turbo EA82 Heads with cracks in the exhaust ports of number 1 cylinder.

 

For me, the cost of parts is small compared to the time and cost of the repairs -- I remember asking about this.

 

This engine supposedly had been built for a hovercraft -- to aircraft standards -- but never delivered, so was offered to me.

 

I sure wouldn't have wanted to be in the air with it, from the way it's behaved.

 

With cracked heads, is there any difference between what you'd do for yourself, vs. for resale? for aircraft use? Or do you consider it really can't have anything to do with the repeated failures, and shouldn't matter?

 

I'm just trying to grasp how come a rebuilder's work can fail repeatedly like this, is it just 'bad luck' it happens?

 

------

Edit: well, so be it. A run of bad luck is a lot more common than people think (so the statistics course taught me, thirty-plus years ago). I recall baseball coaches consistently pull pitchers off the mound after a handful of fouls or strikes, believing they must have lost their touch for the day, well within the number of mistakes that happen normally and about the time their 'luck' ought to turn purely at random.

 

So I'm hoping three failures is just that I got the string of bad luck. If so, y'all owe me (grin) for saving you from it. Keep me posted on what you think is right for rebuilding for yourself vs. for resale, though, if this provokes any thought. I've sure learned that, this round, I've found a conservative mechanic. Wish I'd found him earlier.

 

If anyone needs a good, sober, serious-minded and "old school" Subaru guy around the SF East Bay, try Unitech on Folger in Berkeley. Ask for Bundtha. Tell him that gray haired geek who uses the Internet sent ya ....

 

In sum:

 

The mechanic's agreed to go ahead and do the repair exactly the way the rebuilder says they'll allow under their warranty. No other way we would have a chance at using the car by the end of June. The rebuilder's warranty covers all but the fluids.

Head's gone off to be milled. I'll try to get a good picture of it when it comes back, if time allows.

 

Wish us all luck. News when it happens.

[daeron]

the rule of thumb regarding the cracks between the valves is that if you cannot fit your fingernail into the crack, you are good. both of my heads, on a 140K mile, non turbo, SPFI engine, had rather significant looking cracks in them when I tore the engine apart to do the headgaskets. I didn't even blink. My buddy at the machine shop did a double take when HE saw them, and I was unconcerned because I had seen pictures of identical cracks on the forum here.

 

*I* don't have a camera good enough to have captured and image of them, but if there is a guy who calls himself a subaru guys and says that those cracks are normal.. he isnt TOTALLY BSing you. I realize that you probably don't want to TRUST this guy's word implicitly.. but it is CERTAINLY a very common problem. Did you see the cracks in question? Let your mechanic know the rule of thumb(nail) I mentioned above, and he will probably tell you you are A-OK with it.

[Gloyale]

I've got two non turbo EA82 Heads with cracks in the exhaust ports of number 1 cylinder.

 

The exhauast port is combined so how could there be a crack in just the #1 cylinder?

[Hank Roberts]

Ok, it's out of my hands now, so I'm just being curious.

 

>if you cannot fit your fingernail into the crack

 

Which way are you measuring your thumbnail?

 

This crack measured an inch deep; length is between the valves.

 

The metal ruler ---- thicker than your thumbnail? --- wouldn't reach the bottom of a tapered crack of course. It went in an inch.

 

How thick is the metal on the head total? Is there no oil flow between the valves through a connecting crack?

 

I guess the hammering fix spreads spread the metal on the face to sort of cover the crack. Is that supposed to support the gasket, so it doesn't sag into the crack? Or to keep the oil from the valve stems from going through the crack and up under the gasket?

 

Because that hammered bit came off when the gasket did, leaving the opening full width.

 

This head has a mounting point for a carbeurator, so it began on some other engine. Any way to tell if it's off a turbo?

 

Why would the rebuilder always put new heads on turbo engines, but hammer cracks shut and reuse heads on non-turbo rebuilds? Is the non-turbo so much less stressful that it won't propagate an existing crack?

 

Should milling take the whole surface down far enough that the crack can be hammered shut again? Is oil diverting from one valve to the other via the crack, or doesn't that matter as long as the gasket doesn't get loosened?

 

Does the crack have anything to do with the loud tapping noise on starting the engine up, for ten or fifteen minutes, really loud "machine gun" noise?

That noise has often happened since I first got this rebuild --- was still happening, really noisy, til the seals failed. The rebuilder told me it's a tappet noise and no problem, and others on the forum agreed.

[azsubaru]

The exhauast port is combined so how could there be a crack in just the #1 cylinder?

 

The crack on both heads is down inside the # 1 exhaust port, between the exhaust and intake valves. It doesn't go all the way through to the intake port, but leaks up past the valve seats. Symptom - a regular miss on that cylinder after the engine came up to normal temperature.

[Hank Roberts]

Hmmm. Another symptom never solved on this engine was a shake on idle, warm or cold. Once the RPM was up, it was smooth, but sitting at a stoplight it had a definite miss or beat or shake, at about heartbeat rate. The kind of thing that makes the rearview mirror look like a double exposure.

 

I'd just had it tuned up and smogged a few weeks before the seals blew.

 

Could that be related to the leak in the head developing or the crack between the valves?

[Gloyale]

The crack on both heads is down inside the # 1 exhaust port, between the exhaust and intake valves. It doesn't go all the way through to the intake port, but leaks up past the valve seats. Symptom - a regular miss on that cylinder after the engine came up to normal temperature.

 

That's not the crack I'm reffering to. That is the "Between the Valve" crack. And generally even if they go deep into the head they are still fine. These cracks are on nearly 100% of all EA82 motors and are 99% not a problem. Look in my Photo collection for pics of the exhaust cracks that allow water into the exchaust ports. THOSE are the ones that I've only seen on Turbos.

[Gloyale]

 

This crack measured an inch deep; length is between the valves.[/Quote]

 

The crack can run 1-5/8 inches deep before it will hit cooling passages.

 

How thick is the metal on the head total? Is there no oil flow between the valves through a connecting crack?

 

I guess the hammering fix spreads spread the metal on the face to sort of cover the crack. Is that supposed to support the gasket, so it doesn't sag into the crack? Or to keep the oil from the valve stems from going through the crack and up under the gasket?

 

Because that hammered bit came off when the gasket did, leaving the opening full width.

 

Uhh. the cracks are in the combustion chamber, The gasket does not touch them. The gasket has big holes over the pistons. The wall that the cracks run through is all solid metal dividing the intake and exhaust ports. The crack has to run very deep before it crosses into a water passage.

 

 

This head has a mounting point for a carbeurator, so it began on some other engine. Any way to tell if it's off a turbo?

 

What are you referring to as a Carb mounting point. The SPFI and Carb heads are identical. SPFI heads don't have holes in the side of the exhaust port for ASV pipes, But otherwise they are the same. Tops off the heads are excactly the same. Turbos are all dual intake port heads so there is no way these came off a turbo.

 

 

Should milling take the whole surface down far enough that the crack can be hammered shut again? Is oil diverting from one valve to the other via the crack, or doesn't that matter as long as the gasket doesn't get loosened?

 

Again, the cracks are in the combustion chamber. They won't have anything to do with the Gaskets. And the valves do not have any oil in them so how could oil get from one valve to the other? That wall is just metal, no passages of any kind until the ports diverge. 1-5/8" deep before hitting coolant

 

Does the crack have anything to do with the loud tapping noise on starting the engine up, for ten or fifteen minutes, really loud "machine gun" noise?

That noise has often happened since I first got this rebuild --- was still happening, really noisy, til the seals failed. The rebuilder told me it's a tappet noise and no problem, and others on the forum agreed.

 

This is the Lifters ticking, and is a common thing for subarus. Perhaps resealing the pump would help, but if your oil pressure is high and it only happens occasionally its fine.

[Hank Roberts]

On the machine-gun noise, I found Gloyale has a thread describing something that sounds like mine --- loud on startup til the engine warms up:

http://www.ultimatesubaru.org/forum/showthread.php?t=71978&highlight=head+crack

 

Once the head's redone on mine, I'll follow up in your thread if my noise persists. My engine came apart before he had time to think about the machine-gun noise.

-----

On the location of cracks == if you don't know where the heads on your engine have been --- a head could crack on a turbo then get used to rebuild a non-turbo, eh? I'll ask for a look at that exhaust area before it goes back on my engine. Just in case.

 

The "mosquito fogger" cloud on warmup is how mine failed a year ago, 800 miles ago. But that time the engine went back to the rebuilder and I don't know what they fixed on it that time around.

 

On the depth of cracks, I found one thread where someone actually cut a head apart to dissect out an exhaust area crack. Amazing pictures.

[Gloyale]

Turbo heads are all MPFI and all EA82 MPFI motors, turbo or not have dual ports. An SPFI Manifold will not bolt up. If you're car is SPFI there is no way possible that your heads were ever on a turbo. The Noise I discussed in that thread is definately rod knock, I've diagnosed it for sure now and am building a new motor for that car. I am guessing your *&machine gun * noise is the lifters, and that is a relatively benign issue.

 

Glad you found the splitting headaches thread. I am going to do a similar disection of EA82 heads soon. Just waiting to get them back from being hot tanked. Then you guys will see cracks for sure

[Hank Roberts]

... SPFI there is no way possible that your heads were ever on a turbo.

 

Good to know, thanks. I know this rebuild doesn't quite match --- missing one of four radiator attachment points (radiator place said not to worry) and this mechanic said this head has one carbeurator attachment point. So I knew had been somewhere else, but not how to tell.

 

How about for other kinds of engine? --- someone above noted finding the exhaust port crack on his non-turbo --- could MPFI non-turbo engines have gotten turbo heads during a rebuild sometime? Just trying to sort it out.

 

Looking forward to your hacksaw revelations!!

[Gloyale]

Good to know, thanks. I know this rebuild doesn't quite match --- missing one of four radiator attachment points (radiator place said not to worry) and this mechanic said this head has one carbeurator attachment point. So I knew had been somewhere else, but not how to tell.

 

How about for other kinds of engine? --- someone above noted finding the exhaust port crack on his non-turbo --- could MPFI non-turbo engines have gotten turbo heads during a rebuild sometime? Just trying to sort it out.

 

Looking forward to your hacksaw revelations!!

 

There aren't any radiator attachment ports. Unless you mean the the radiator hose don't even attach to the heads. Do you mean the exhaust studs? thats the only thing I can think 4 of. Man if this shop thinks those are radiator attachments no wonder there is trouble.

 

As far as MPFI, i suppose it's possible turbo heads could end up on a NA-MPFI(non-turbo) motor. But 98% of those motors are in XTs or have are transplants into GLs or Loyales. Hank what year Subaru do you have?

[Hank Roberts]

There aren't any radiator attachment ports.

 

My mistake--my typo -- not "port"--- I meant "point" -- attachment point. Bolt hole, bracket --- for attaching what goes in front of or on the top of the engine.

 

The car's at the shop I can't describe it any bettter.

 

Don't leap to decide the mechanic's at fault -- I see that a lot on USMB, and for most of y'all it's true you know a lot about these and many mechanics don't

 

This is the opposite. I finally found the guy who's worked on these for decades, in his quiet little corner way across town.

 

I've only had this one Subaru, for, less than three years. So if something sounds wrong, suggest I need to learn better first, it's almost surely my mistake.

 

 

So -- clearing up my fog:

 

On the right head, last week, the mechanic said this head originally came off an engine with a carbeurator-- no problem, pointing to where some pollution control part would attach to it for a carbeurated engine.

 

That's why I was asking, what kind of engine could this head have come from. Thanks for that reassurance it's not been on a turbo in its past.

 

Now -- long ago:

 

I always look for forgotten hoses, loose wires, mislaid tools, drips, half eaten ham sandwiches and stuff under the hood. I've found all of them in the forty years I've been driving cars. I used to be able to work on my own, too. Some of them were my fault.

 

On the Su, an earlier time, I noticed a part (radiator? fan? something that sits on the engine) had been put back on after the rebuild -- but it had a flange that didn't line up with a bolt hole, sticking out obviously unattached.

 

I asked what they had left out(!).

 

That shop (the old one) said no problem, the rebuilder replaced your left head with one from a different engine -- it doesn't have a bolt hole there.

No problem, three out of four bolts lined up [radiator? fan? whatever it was]. Hope that fits what you know. "Attachment point" not "port" -- my typo.

 

This is the only Subaru I've ever had (a hasty replacement for a Tercel 4wd wagon, that got stolen and trashed three years ago).

 

The left head was replaced 2 years ago --- on the first warranty repair--- by the rebuilder; they said they checked the right one as well, that time, 2 years ago. They said that was their shop's screwup, high and low spots left from grinding the head. The car never got off the rack that time, it leaked as soon as the engine was put in and filled, and it went right back immediately.

 

That lasted a year; leaked, went back; repaired, ran another 800 miles, leaked, and that's today.

 

 

As far as MPFI, i suppose it's possible turbo heads could end up on a NA-MPFI(non-turbo) motor. But 98% of those motors are in XTs or have are transplants into GLs or Loyales. Hank what year Subaru do you have?

 

This is a 1988 GL - SPFI - non-turbo - 4wd - 5-speed dual range wagon.

 

I got it for the low gear range, for slow steep mountain roads doing field botany work and taking kids camping.

[Gloyale]

So -- clearing up my fog:

 

On the right head, last week, the mechanic said this head originally came off an engine with a carbeurator-- no problem, pointing to where some pollution control part would attach to it for a carbeurated engine.

 

That's why I was asking, what kind of engine could this head have come from. Thanks for that reassurance it's not been on a turbo in its past.

 

 

If he was pointing near the bottom of the head at the exhaust port, he could have been talking about the ASV port. And to use a carbed head on SPFI you just need to tap and plug that. Has that been done? Other wise there is no difference at all betwen the Carb and SPFI heads. No part of the radiator or fan bolts to them however, anywhere.

[Hank Roberts]

>ASV Port

Yes, that sounds like what he showed me on the right side head

(properly plugged, said the head would've started life on a carb engine).

 

Do you have a picture showing how the usual crack between valves looks?

I know the engine rebuild includes new valve seals; don't know how that fits with cracking, can a 1" deep crack allow any pressure to bypass the valve seals? I gather hacksawing through those would be real tiresome to get a cross section?

[Gloyale]

>ASV Port

Yes, that sounds like what he showed me on the right side head

(properly plugged, said the head would've started life on a carb engine).

 

Do you have a picture showing how the usual crack between valves looks?

I know the engine rebuild includes new valve seals; don't know how that fits with cracking, can a 1" deep crack allow any pressure to bypass the valve seals? I gather hacksawing through those would be real tiresome to get a cross section?

 

Well, the "splitting headache" thread from Gravityman in the retrofit forum has pics of the cracks. I've had several heads with the BTV cracks that pressure tested fine. I've seen a few where the crack was big enough to let a little by but still "passed" the test.

 

And Valve "seals" are not the same as Valve "seats". The seal is under the spring on the lifter end of valve. These are viton and usually are replaced during rebuild. They keep oil from pulling past the valve stem into the intake.

 

Valve seats are the hardened, angled, rings that the valve faces close against in the combustion chamber. I don't think it is alway the practice to remove these seats. Ussually they are lapped or ground in place on the head. Fitting new ones requires special presses and in some cases a liquid nitrogen dip to super cool the seat and shink it. Then it's fitted into the head and when it expands it is permanently seated the head. I doubt that the seats were removed. If they had been removed then at that point welding the crack is a snap, and that would be the only real *fix* to the problem. But 1 in deep is fine. Again there is 1 5/8 inches before the crack would hit coolant.

[Hank Roberts]

...1 in deep is fine. Again there is 1 5/8 inches before the crack would hit coolant.

 

Got it. I'll ask how thick the probe was he used, to measure the crack down to that depth. Hope it was really thin and the rest of the crack doesn't extend much further into that 5/8" remaining. I assume cracks keep getting deeper.

 

Is there any practical difference once it happens, between a leak when that kind of a valve crack gets down to the coolant channel, versus a leaky head gasket that gets to the coolant channel where it crosses the gasket? Any difference in what happens, how it looks, or how to handle the vehicle if it happens on the freeway for instance?

 

I can't say I feel exactly lucky. But I'll have another 10 months or so of warranty on the engine, so want to watch it carefully assuming it gets fixed this time around.

 

Any "look hard" advice to catch problems early, before the big cloud of smoke and steam stage, that I should be checking regularly? I know to look for brown gunk in the oil and oil in the coolant and white fog out of the tailpipe and oil smoke out of the tailpipe and puddles under the car -- seen all that! But is there anything to check to catch an engine seal failing before the public embarassment on the freeway stage I should be doing?

 

Like Mr. Reagan said: "trust, but verify" --- seems appropriate by this time.

[daeron]

watch your coolant like a hawk, in all ways. i had my blown hg and the most significant symptom was the bubbling into the overflow caused by the introduction of cylinder compression into the radiator via the blown headgasket, and you would be encountering something similar if the crack finally rent asunder into a coolant passage.

[soobscript]

Pics of good and bad cracks:

http://s21.photobucket.com/albums/b260/soobscript/ValveCracks/

[Gloyale]

Pics of good and bad cracks:

http://s21.photobucket.com/albums/b260/soobscript/ValveCracks/

 

 

Wow thats a great set of pictures for everyone.

[daeron]

Pics of good and bad cracks:

http://s21.photobucket.com/albums/b260/soobscript/ValveCracks/

soobscript:

 

Could you please be so kind as to upload these photos onto an album here on the USMB, and make a post that we can nominate for the USRM with them all???

 

This is excellent visual data that would be nice to be able to pass on. If only we could get good examples of acceptable BTV cracks, it would be super.

 

BTW, since I didnt remove the valves from my heads, i REALLY hope my heads arent cracked that deeply...

[soobscript]

Could you please be so kind as to upload these photos onto an album here on the USMB, and make a post that we can nominate for the USRM with them all???

 

This is excellent visual data that would be nice to be able to pass on. If only we could get good examples of acceptable BTV cracks, it would be super.

Yeah, when I get around to it...

Both Gen3 heads I pulled from my RX were cracked like that and warped.

Got very lucky (rust belt) and found a turbo motor in the yard. Even better was the fact that only 1 tiny BTV existed. Came from a 93 auto t-wag. Built the motor, wrecked the car, motor is bored now.

[daeron]

I *might* decide to "get around to it" before you; IF I were to do that, and credit you for the photos, would you mind?

 

Me== no job right now, too damn much time to kill.

 

BTW, you DO know that paintbrush has a text insertion tool, dont you?