Grinding the head

[Hank Roberts]

Can y'all specify how you measure the depth of a crack? Do you insert a thin wire or feeler gauge, something that can fit into an irregular crack til the crack is the same gauge? Or a straightedge metal ruler inserted into it? Or whether it appears beyond the bottom of the valve seat (seat, the Some of those cracks pictured look (gulp) really wide and ragged, and obviously the bad ones extend past the bottom of the valve seat. This is really interesting. When my right head comes back from being milled, I hope I can photograph and measure it --- I want to know how y'all do your measurements. And I want to send the pictures and measurements to the rebuilder and get confirmation what's left of their warranty continues to be good after putting this back on. I looked back at the old notes and the first time this engine failed, on first delivery, the left head was so damaged by their grinder guy that they replaced it they said with a new head. I sure hope that's right. Two cylinders good ... four cylinders better, eh?

[Gloyale]

Can y'all specify how you measure the depth of a crack? Do you insert a thin wire or feeler gauge, something that can fit into an irregular crack til the crack is the same gauge? Or a straightedge metal ruler inserted into it? Or whether it appears beyond the bottom of the valve seat (seat, the Some of those cracks pictured look (gulp) really wide and ragged, and obviously the bad ones extend past the bottom of the valve seat. This is really interesting. When my right head comes back from being milled, I hope I can photograph and measure it --- I want to know how y'all do your measurements. And I want to send the pictures and measurements to the rebuilder and get confirmation what's left of their warranty continues to be good after putting this back on. I looked back at the old notes and the first time this engine failed, on first delivery, the left head was so damaged by their grinder guy that they replaced it they said with a new head. I sure hope that's right. Two cylinders good ... four cylinders better, eh?

 

I've never tried to insert anything into the crack. I don't think that would give you an acurate assesment. The crack could be less than .001 wide but still be a crack, and how would a gauge fit in there? And a ruler wouldn't work unless you removed the valve seat. If I have a question about those cracks I ussually pull the valves and inspect inside the ports. If the crack extends into the portion that starts to bend there may be trouble. But even then there is hope because that wall is fairly thick there. On an NA motor I wuln't expect themn to be too bad. For me, If they vac test good then I use them.

[daeron]

man, i cant get those BTV crack photos out of my mind now... but with compression numbers like 180, 185, 185, then 150 for my bad cylinder I suppose I shouldnt be too concerned that mine cracked that deeply. especially on an NA. BUT now I really wish I had bothered to take a valve or two out of each head when I had the engine apart... "wish I had" syndrome, yanno

[Gloyale]

I slapped together a EA82 Turbo out of spare parts to get a car from Oregon to Wisconsin. The heads I put in are Gen 1's from an XT. The valves we're rusty as sin so I had to swap them out with ones from a different head. Anyhow the BTV cracks in these heads were tremendous. One cylinder it was 2 small parallel cracks leaving a little block in the middle. All buckled up a bit and definately could get my fingernail in a bit. Cracks went nearly all the way down to the bend in the port. But the exhaust ports looked good from the bottom so I went with em. I had to beg the machinist to even exctract a broken cooling line bolt, he didn't want to even see them with those cracks. but in the end 20,000 miles and 3 cross country trips later the bottom end is dying (rod knock) but the motor runs great. Good compression, good boost, no coolant lose, no smoke, no overheating. I wouldn't worry too much Daeron

[daeron]

I slapped together a EA82 Turbo out of spare parts to get a car from Oregon to Wisconsin. The heads I put in are Gen 1's from an XT. The valves we're rusty as sin so I had to swap them out with ones from a different head. Anyhow the BTV cracks in these heads were tremendous. One cylinder it was 2 small parallel cracks leaving a little block in the middle. All buckled up a bit and definately could get my fingernail in a bit. Cracks went nearly all the way down to the bend in the port. But the exhaust ports looked good from the bottom so I went with em. I had to beg the machinist to even exctract a broken cooling line bolt, he didn't want to even see them with those cracks. but in the end 20,000 miles and 3 cross country trips later the bottom end is dying (rod knock) but the motor runs great. Good compression, good boost, no coolant lose, no smoke, no overheating. I wouldn't worry too much Daeron

 

I'm not worried TOO much.. I just cant get the image out of my mind, thats all. I am kinda morbid like that sometimes.

 

I am STILL kicking myself (occasionally) over the spark plugs...

[Hank Roberts]

daeron wrote: I'm not worried TOO much.. I just cant get the image out of my mind, thats all. I am kinda morbid like that sometimes. Well, I wonder, too, things like:

-- When cracks are welded, is the welding actually filling the crack all the way down to the bottom, or just covering over the top of it? Doesn't the crack continue to propagate, or is holding the top edges together with welding keeping it from getting deeper?

-- Where does the metal _go_ that was in the cracks?

I'm assuming it doesn't just disappear or shrink, but that the hollowed out part of the head holding the valves is changing shape somewhat. So that might argue that welding the top of the crack stops it from getting deeper. But .... I guess using that hacksaw is the only way to know for sure.

-- Aren't combustion chambers sensitive to shape such that some fuel and air are in the crack and burn poorly or change the combusion process?

My mechanic, who says he'd never reused a cracked head on any Subaru in 20 years, also says the "noisy hydraulic lifter" noise isn't normal in these engines.

-- Is the measured oil pressure at the sensor likely to be inaccurate with cracks between valves like those pictured? Or, a better question, have y'all who did find cracks there also had the noisy lifter tapping even with good oil pressure readings?

Just wondering.

[daeron]

My mechanic, who says he'd never reused a cracked head on any Subaru in 20 years, also says the "noisy hydraulic lifter" noise isn't normal in these engines.

 

Just wondering.

 

I can't answer any of your other ponderings.. but I know that my motor had FANTASTIC compression numbers in the "good" cylinders when I confirmed a bad headgasket, and ALL cylinders had significant cracks BTV.. I didnt examine the depth at all because the valves stayed in, but... I was getting 185 PSI out of the good cylinder bank, and 155 out of the bad ones. (exact numbers, i found the sheet of paper I wrote them on yesterday.)

 

And if your mechanic says he has never heard the TOD..... I mean, just.. WOW!!! has he NEVER seen a subaru that had been run with anything less than the finest oil, changed with filter every 2500 miles, and a new oil pump every 60K or so??? there are like four or five MAJOR contributors to the tick of death (the HLA noise) and more minor ones than I can think of.. poor oil pump pressure, oil pump seal collapse causing poor oil FLOW, any oil leak, any contamination in oil, slightly worn lifters, lightweight oil..... LOTS of things.

 

I hate to call this guy's opinion into question over his statements about the TOD.. it Could be that he does just make sure they are all fanatically maintained.. BUT everyone here who has seen their cylinder heads knows that the valve cracks are very common (or we have run many heads with valve cracks. I have only used the pair on my engine currently, but others have FAR more miles on far more engines than I) AND we know that noisy lifters are sometimes just a way for the car to politely ask that its oil get changed. I wouldn't lose sleep over it.

[Gloyale]

there are like four or five MAJOR contributors to the tick of death (the HLA noise) and more minor ones than I can think of.. poor oil pump pressure, oil pump seal collapse causing poor oil FLOW, any oil leak, any contamination in oil, slightly worn lifters, lightweight oil..... LOTS of things.

 

 

Don't forget the that worn main and rod bearings will lower the pressure of the oiling system and contribute to TOD. But basically a bit of TOD is something that can happen to any Subaru.

 

Hank as for the cracks affecting oil pressure and combustion shape. First no, BTV cracks have no bearing what so ever on the oil pressure or TOD. As for incomplete combustion I think the only affect they could have is if they were bad enough to affect overall compression. The slight deformation of the combustion chamber is minimal in consequence.

 

Most Mechanics that have to pay liability insurance won't use a cracked head on principal(principal on the loan they took out to pay for it). Although I suspect he is not a subaru specialist. If he insists on replacing your heads with new ones to the tune of $600 per set or more, it's to cover his own rump roast. Not because these cracks are going to make the car stop running or have problems.

 

Seriously, I had a Carbed GL with moderate BTV cracks in every chamber for who knows how long. I had driven it about 15,000 miles, then at 160,000 miles I redid headgaskets because of external oil leaks. Drove it another 40,000 miles (actually took the engine out of the first car and put it in a new one) Then sold it still running sweet. Compression over 165 in all cylinders. 26 mpg avg.

[Hank Roberts]

>"fanatically maintained"

That's right

>"not a Subaru specialist"

That's wrong. He's a pro, not a home-builder. Different standard of care.

 

He's worked on local older gen Subarus for a very long time. He cuts no slack. As you say, liability insurance requires not cutting corners.

 

The engine rebuilder was honest with me --- they told me they can't afford to do their rebuilds to this guy's standards every time. They've sent at least one other customer to him since I found him.

 

YMMV as always.

[Gloyale]

non the less even subaru has said these cracks are *acceptable defect* for rebuilding. And it's not a different standard of care, it's a standard of money and liability. There are millions of Subarus driving around with these cracks in the head doing fine. Those brand new heads you pay for crack within 10-20K miles then you're back in the same boat. Even the rebuild seems to be telling you this.

 

If you really want to fix the cracks welding is a great idea. Of course it requires removal and refitting of the valve seats. But to address your question earlier about it, no you don't just weld the surface shut. You (or your welder more likely) would grind out the material from the crack, all the way to it's end. By grinding it away you ensure that you get all the way to solid metal. In this case it would be a channel on each side of the seperating wall between intake and exhaust. Then you would weld in fill material to close it all back up. Drag race and short track guys do stuff like this all the time with their aluminum heads. Take them to someone familiar with aluminum head welding.

[Hank Roberts]

>TOD

Well, I've talked to a lot of local GL owners in the past 2 years and they don't recognize the noise either (when I pull up next to one in traffic, sometimes, when mine was doing it, I'd ask!!). It may be temperate climate here, or people who do a lot of maintenance (serious smog check requirements?). I"m sure there are 4-wheeler Subaru beaters that recognize it. Remember I'm an old fossil driving very gently, except in the national forest logging roads and then in 4wd low range low gear at 8mph.

I'm not around anyone who pushes a Subaru hard for fun or beats it up.

 

non the less even subaru has said these cracks are *acceptable defect* for rebuilding.

 

I'd appreciate a pointer to Subaru's spec on that, out of curiosity.

 

Note, some of this thread is general advice others can use later.

 

To keep clear what's general, separate from the specific for me ---

 

Take them to someone familiar with aluminum head welding.

 

Very helpful and clear about how to get heads welded. I hope we hear from someone who's gotten it done further down the thread with pics!

 

And if anyone's sawed through a welded head later, pics please!!

 

Mine won't get welded -- it's under warranty, what's fixed is decided by the rebuilder; rather than ship it interstate again, they're working with the local guy to do the warranty repair for this third leak.

 

On mine specifically:

Rebuilder and this mechanic _both_ agree they don't rebuild engines by his standard; he's, as you said, fanatical.

 

They rebuild them in large volume. He does one at a time.

 

He _does_ need a reliable source for rebuilt Subaru engines that are affordable.

 

I told him about the rebuilder; they told him they quit fixing heads with that kind of grinder a year or two back.

 

They use a rota-something softer tool now. so, they may agree more on what's reasonable for rebuilds. If so he'll buy from them -- he can sell people their cheaper rebuild here and keep more Subarus running, if he accepts it's good enough. He knows his one-at-a-time are too expensive on these old cars.

 

If it works out --- he'll get a supplier; the rebuilder will get a local warranty guy; and I'll have an engine that holds fluids finally.

 

----> So thanks generally for all the thoughts. Wish us all luck.

[daeron]

Most Mechanics that have to pay liability insurance won't use a cracked head on principal(principal on the loan they took out to pay for it).

 

 

I nominate this for "pun of the year" principle, principal..... PRICELESS

[Gloyale]

 

Originally Posted by Gloyale

non the less even subaru has said these cracks are *acceptable defect* for rebuilding.

 

 

I'd appreciate a pointer to Subaru's spec on that, out of curiosity

 

Sorry I was just told that by a friend who worked at the dealership.

 

And as far as welding I haven't had those cracks welded but I have had exhaust cracks on my turbo heads welded up. It's just about the only option anymore for MPFI heads. New gen 3 heads are getting rare and are spendy. Finding a good set is maybe 1 in 10 odds at best(NA XT is the best bet). Most all gen 1 and gen 2 Turbo heads have exhaust cracks at least begining. They don't always crack through to the coolant passage. But of course they have the BTV cracks and possibly cracks between the edge of the valve and spark plug hole. I'll put up some pics. Sorry no dissection of the welded heads yet.

[Hank Roberts]

Sorry I was just told that by a friend who worked at the dealership.

Dang. I'd sure like to have more than friend-of-a-friend being _told_ that. It'd take pretty good statistics to know it's true. I'd hoped it would be on the record somewhere. Too bad.

 

Ok. I took another look at the cracked head today and asked how the 25mm was measured.

 

He simply measured the vertical distance from the face of the meta. The cracks visible opening goes down the vertical wall between the valves, and widens out into the curve at the base of the hole.

 

They look a lot like the ones your pictures labels bad. Maybe not so wide at the narrow top, but they'd been hammered there. Wider below the hammered area, then narrower as it goes deeper, visibly stained around the cracks lower down, can't tell if it's liquid leaking out from the crack or discolored metal around it, kind of greenish brown color.

 

I couldn't get pictures today, may try again.

 

Both pairs of valves are cracked about the same.

 

I guess there's no way to tell for sure --- X-rays maybe? ---how much deeper either crack goes toward the water channel in the thicker part of the metal. The cracks are certainly too irregular to get a feeler gauge into them. I can just see taking it to my dentist .... does anyone X-ray aluminum castings to detect cracks?

 

When you cut sections through cracked heads, did the bottom of the crack go deeper in the thicker metal, in between the valve holes, below the place the metal curves, do you know? Or was it a straight line across between the valves once it got into the thicker metal there? Or does it crack less deep in the middle than out at the valve hole area?

 

I read up on aluminum cracking, it's not reassuring. Aluminum cracks eventually in use even when it's well made, and the cracks propagate with changes in temperature and pressure. That's different from steel, which can be made well enough that it has little variations that halt crack propagation. Or so Wikipedia says (sigh).

 

So much to know, so little time to learn it.

[Gloyale]

Dang. I'd sure like to have more than friend-of-a-friend being _told_ that. It'd take pretty good statistics to know it's true. I'd hoped it would be on the record somewhere. Too bad.

 

 

Well my own personal statisticts are 100% of the engines i've opened for new headgaskets have had them.(that's about 20 or so)

 

1 Set of turbo heads was so bad I chose not to use them, but they had exhaust cracks too, If not, I might still have used them. And even the heads I did find for that motor had BTV cracks too.

 

So that's 20 resealed motors with 100% BTV cracks and every one fired right up and lost no coolant. no one has ever complained or brought their car back. 6 of those engines I'm still in close contact with the owners and they are still fine. some of them going on 50,000 miles since my reseal.

 

Seems 100% is a pretty good statistic.

[daeron]

21, but ive only got about 3K on mine so far, since the head job.

[azsubaru]

Dang. I'd sure like to have more than friend-of-a-friend being _told_ that. It'd take pretty good statistics to know it's true. I'd hoped it would be on the record somewhere. Too bad.

 

MAybe this will help. I've seen a Subaru FSB about it in Mitchell's Online database.

CYLINDER HEAD CRACKS Cylinder Head Cracks On 1985-92 Subaru 1.8L OHC & OHV Engines AERA members have reported cracked cylinder heads on 1985-92 Subaru1.8L OHC and OHV engines. These cracks occur in the combustion chamber ofthe head between the valve seat inserts (see illustration). The cause of these cracks is usually related to an overheated engine.It has been determined by Subaru that this crack does not leak coolant into the chamber and the cylinder heads should not be replaced. Extensive testing indicates that under pressure testing, the heads do not leak unless the cracks are termed extensive Pressure testing is still advised to assure your customer of the heads integrity. Checking both valve seats for looseness is also necessary as insufficient press fit may allow the seat to move during engine operation.A modification to that area of the casting was made during 1991 production to chamfer and increase the distance between the valve seats. That change has reduced the number of heads that crack.Some AERA machine shops remove the valve seats, weld the cracked area and reinstall valve seats to give the head a more acceptable cosmetic appearance. The AERA Technical CommitteeJanuary 1996 - TB 1300

[Gloyale]

MAybe this will help. I've seen a Subaru FSB about it in Mitchell's Online database.

CYLINDER HEAD CRACKS Cylinder Head Cracks On 1985-92 Subaru 1.8L OHC & OHV Engines AERA members have reported cracked cylinder heads on 1985-92 Subaru1.8L OHC and OHV engines. These cracks occur in the combustion chamber ofthe head between the valve seat inserts (see illustration). The cause of these cracks is usually related to an overheated engine.It has been determined by Subaru that this crack does not leak coolant into the chamber and the cylinder heads should not be replaced. Extensive testing indicates that under pressure testing, the heads do not leak unless the cracks are termed extensive Pressure testing is still advised to assure your customer of the heads integrity. Checking both valve seats for looseness is also necessary as insufficient press fit may allow the seat to move during engine operation.A modification to that area of the casting was made during 1991 production to chamfer and increase the distance between the valve seats. That change has reduced the number of heads that crack.Some AERA machine shops remove the valve seats, weld the cracked area and reinstall valve seats to give the head a more acceptable cosmetic appearance. The AERA Technical CommitteeJanuary 1996 - TB 1300

 

I knew that I had read it somewhere. But my for sure verified source was the friend at the dealer. This explains both.

[Hank Roberts]

I knew that I had read it somewhere. But my for sure verified source was the friend at the dealer. This explains both.

 

Fantastic. Is that last TB 1300 the Subaru tech bulletin number?

 

I think you've just made my mechanic _and_ the engine rebuilder very happy by finding that.

 

I (and they) will still wonder why my engine _did_ leak at several different gaskets, three times (wince) -- but at least we all can cross this other worry off the future problem list.

 

And that puts us back on topic as well. Sorry for the digression, but it's been _very_ educational and will continue to be.

[Gloyale]

I (and they) will still wonder why my engine _did_ leak at several different gaskets, three times (wince) -- but at least we all can cross this other worry off the future problem QUOTE]

 

I've had aftermarket gaskets develope external leaks. Sadly the main oil passage to the heads is at the very bottom of the head kinduv in an ear. It's close to the head edge and doesn't get sqeezed "between" any of the head bolts. Fel-pros have a pretty good o-ring built into the gasket there and are the best choice after Subaru.

 

for my self though, i use the cheap ones, but I retorque after 500 miles. And if it leaks I can change them out almost in my sleep again myself. But If I am doing the job for someone I go OEM or Felpro, cause they work best with no retorque.

[Hank Roberts]

I (and they) will still wonder why my engine _did_ leak...

 

This rebuilder did use OEM gaskets (so I understand from the rebuilder); they sent the replacement gasket for the right head being redone here this time, so they know it matters what's used. Well, we'll see how it works. I wonder if this mechanic retorques or not. Guess I'll ask. I gather that's a variable.

 

I don't suppose overheating can make the bolts (I guess I mean studs?) any less springy? I know the torque's supposed to stretch them slightly so they pull down on the head --- does overheating an engine cause the threaded part to lose some of their temper so the torquing doesn't cause the proper amount of squeeze? Or is that not possible in this situation?

 

(Like I said, I don' t know the history of this engine, it was a rebuilt on the shelf there and they swapped it for the one I sent them to speed things along. I hope it didn't come out of a fire or something, since it was meant to be on a hovercraft in Europe, who knows where it'd been. Or can you tell that?) Don't mind me, just daytime waking nightmares ...

 

Most informative topic, thanks all.

[beataru]

If they are a reputable shop... example, someone other than joeshmoes auto... than they probably used felpro or same quality... felpro makes many of the gaskets for manufacturers so they are a good alternative to OEM... And overheating an engine can screw everything over... the engine is metal, Metal expands and contracts with heating and cooling, but as you have probably seen with seran wrap (pardon me if I spelt it wrong) the you can notice that if you stretch the wrap too much, it will be deformed in that spot and will not shrink again. Same principal with an engine... the bolts can stretch, actually that is what they are intended to do! thats why you torque them a certain way, the bolts stretch, they keep a certain tension and your engine runs... but over heating an engine wont make them less springy, its everything that gets screwed, your head gasket will become more crushed and then once the engine cools, and then reheated, this time to normal operating temp, it is crushed too much and you have a leak. So thats a basic reason why too much heat is bad bad bad for an engine... I hope it helps......

[Hank Roberts]

... the bolts stretch, they keep a certain tension and your engine runs... but over heating an engine wont make them less springy

 

That's the only part that applies to my question.

 

I know steel 'loses its temper' (hardness, springiness) on overheating -- you are sure that an engine overheat cannot affect engine bolt springiness?

 

Just puzzling what else could be checked before this engine goes back together--my warranty's got less than a year left on it now.

 

Why do some people retorque the bolts after the engine's been run, and others don't?

[Gloyale]

That's the only part that applies to my question.

 

I know steel 'loses its temper' (hardness, springiness) on overheating -- you are sure that an engine overheat cannot affect engine bolt springiness?

 

Just puzzling what else could be checked before this engine goes back together--my warranty's got less than a year left on it now.

 

Why do some people retorque the bolts after the engine's been run, and others don't?

 

These engines do not use the "Torque to Yeild" bolts. And they are bolts, not studs. (studs would be better actually) They should not stretch, nor lose there temper or effectiveness(unless they are removed and reinstalled dozens of times perhaps). The temper is created by 1000's of degrees heating and quenching. Even a massively overheated engine produces only in the hundreds of degrees. The threads in the block are a different story though. They are soft alloy and can be affected by overheating. It's really good to chase them out with a tap before reassembly. Trouble is they are a rare M11 x 1.00 size that's hard to find a tap for. Carefully running a bolt in and out of them a few times with some wd-40 is another option and works pretty well.

 

Most shops don't retorque cause it would mean you bringing the car back to them in a month or 2 and paying to have it worked on again. Fel-pro and other manufacturers claim there gaskets not to need it as well. I retorque mine cause I use cheaper gaskets and Subaru says to. Sure I have to remove the valve covers, and the Oil tube above the rockers, but I like the peace of mind. Once you try it once and realize some of those bolts have loosened and NEED the retorque you will never not do it again.

[Hank Roberts]

... I retorque mine ... Subaru says to.... Once you try it once and realize some of those bolts have loosened and NEED the retorque you will never not do it again.

Ding. This may be the winning answer. Shudder.

 

How long do you run the engine (time? distance?) before retorquing?

That has never been done on this engine, not when it was first rebuilt and not after the two repairs at the rebuilder's shop. I'd asked the rebuilder, they told me retorquing isn't needed; they use Subaru gaskets.

 

Hmmm. The left head has been on 800 miles, since they resealed the engine a year ago -- or else under 2k miles, the rebuilder replaced it the first time it leaked.

 

Is retorquing something that can be done cold? I wouldn't regret paying to get the left head checked now, even before the right one goes back on, just to know. Else I'm going to ask the local mechanic if he retorques routinely, and ask him to check both of them.

 

How long do you run the engine before retorquing?

 

How often do you find some loose, when you do the retorquing? I know, _once_ is enough to convince me it needs doing.

 

I'm getting hopeful again.