I hope this pic works ..

 

And if it is ruined shouldn't the machine shop guy have said something about it?

I would be scared as hell to use it. He probably just did the machining, took your check, and didn't think twice.

yeah..... i prob. wouldnt put that back on any car.......

doesnt look good to me

I'd throw the head through the machinist's Ford truck's back window!

You are just asking for trouble using a head in that "pit"iful shape. I don't know if it can be reworked, but suggest returning the head to the machine shop to see what the shop manager has to say.

Ya looks bad. Time for JB weld??

It looks like scrap to me.

 

nipper

were the pits there before you dropped the head off? If it were my head I would have pointed out the pits and asked if they were going to be an issue ...before any work was done?

The pitting on the deck isnt an issue for me, the pitting on the edge of the combustion chamber is impossible to fix, and can cause pinging if it makes a hot spot, and a path for hot gases to blow the HG.

 

A good machine shop should have refused to do the work.

 

nipper

SO here's the story:

There was a lot of carbon build up and blow-by from the head gaskets being blown. I do NOT remember seeing any pitting or damage to the heads. The machinist said (and I verified) that this pitting is all inside the combustion chamber. NO part of the headgasket touches any of this pitting. Anywhere the gasket touches the head is smooth and freshly machined. He said 1 in 5 aluminum heads that he works on has some pitting in the combustion chamber in this manner. He claims he has been a machinist for 26 years and this should pose no kind of problem. I do not see any pitting or damage on the respective piston.

Well, the fix would have been to weld/fill the pits FIRST, then machine it. Totally doable. But that time is past.

 

 

I don't think it's so terrible that it wouldn't run. I don't think you'd notice any problems at all.......at first.

 

As other said, it could lead to hot spots and blown HG down the road. But my gut says probably not. I've seen worse come out of running engines.

 

Is this you're car? What are you're expectations of it? If this isn't a Hi-Pro build or you're wifes car , you could run it. Perhaps clean the edges up a tad with a file. Looks to be all in the combustion chamber, so the HG mating surfaces should be OK. I bet it would run great for a long a** time.

 

It all depends on perspective, and how long you need to rely on it to last vs. you're wilingness to push the limits. I'd run it just for the hell of it on an offroader.

 

This isn't a rare head though, so seems better to suck it up just get a new one.

 

 

EDIT: A second look makes me even more sure. I'd run it. It looks a whole lot worse at first glance. A tad lower compression in that cylinder ain't gonna hurt nothing. I would file any very sharp edges though

I would file any very sharp edges though[/color]

 

 

Shouldn't he use a honing stone so as not to put file marks on the freshly machined surface? Not trying to be obnoxious. Genuine question:)

 

Will-

i have used worse with no ill effect, as long as none are on the headgasket edge i would not worry about it

i have run much worse on toyota's

Is this you're car? What are you're expectations of it? If this isn't a Hi-Pro build or you're wifes car , you could run it.

 

It's my mothers car... may be mine some day down the road... We would like to see it make another 100k at least without anything else too major going wrong. It was supposed to be a winter/family car for the snowy roads, etc.. at $3k with no apparent problems (except a minor run in with a deer, that got repaired) it seemed like a deal. With-in a week it started pushing coolant out and i tried a couple fixes but it was just getting worse so we've spent nearly another $2k to get all the stuff to "fix it right" ... half this motor is going to be new.. oil pump, water pump, belts, pulleys, plugs, wires, filters, seals & gaskets, knock sensor, radiator, mirrors, etc, etc.

I guess I'm going to put it back together and hope it doesn't blow any time soon. We'll be sure to be prompt with maintenance.

If you've got $5k into the car already and are hoping for a trouble free 100k miles... why put it back together with an iffy head? Maybe you can get another head from a junkyard and have it machined? At this point you'd be nuts to 1/2 a$$ it.

I have used worse on motors with no problems. Run it!

Depends...how bad is your anxiety problem?

I would run it. As long as it doesn't touch the gasket it should be fine.

 

This isn't a race engine so this "hot spot" theory is horse puckey. If it was turbo, or a high RPM engine..... maybe. But probably not even then. Lots of combustion chambers are not polished in regular street engines.

 

Fixing it would cause more harm than good. Take a polishing stone and smooth out the high spots if there are any.

 

GD

i've never seen one like that. could it have had damage prior that you just didn't see? i wonder if it previously bent some valves due to a timing belt escapade?

 

i'd probably use it, based on the comments of these guys, and if by inspection the pits are all within the headgasket sealing surfaces.

i've never seen one like that. could it have had damage prior that you just didn't see? i wonder if it previously bent some valves due to a timing belt escapade?

 

i'd probably use it, based on the comments of these guys, and if by inspection the pits are all within the headgasket sealing surfaces.

 

It seems to me that the damage was probably there but covered with carbon. The machinist has 26 years experiance. He also did the valve job, etc. He even replaced parts that needed it, and gave back the old ones. He assumed that a piece of a spark plug or something may have come off and banged around in there. He was confident that it wouldn't cause any problems and that none of the gasket touched the pitting. I checked and he was right, none of it is touching the gasket. It's all in the combustion chamber and it's only on the #1 cylinder. Getting intimate with this car it is obvious that it had a HACK mechanic working on it. I forget who said it.. but they said "The only thing that will truely ruin these cars is bad mechanics." LoL isn't it the truth!

That's NOT pitting - the surfaces look like physical damage to me (impact damage) from something small - like a spark plug electrode? Some of the surface ares in the valve areas look like small pits (I can blow up the drawing to 5X on my machine) but the semi-circular ones look like a tossed object (I do some failure analysis). If you can use "image zoom" (Firefox add-on) look closely at the major "pit" 4-o'clock position at the combustion chamber to head interface - the mottled pattern is characteristic of "pitting". There are a few others as well. It had a blown head gasket? Run for how long with the head gasket blown? Aluminum (depending on the alloy but this is likely A357) can do an exfoliation pitting pretty quickly under the pressures and humidity of engine operation. it's kind of difficult to do both a failure "estimation" and "probable metallurgy" from a picture without specific data. There's NO damage apparent on what is visible on the next cylinder.

 

IF you polish the damage to a smooth surface by removing as little metal as possible (least expensive but does change the exact cyl-to-cyl compression balance by a small amount) or have it welded (more expensive and might cost as much as buying a head off a wreck), you can salvage it but it isn't something you want to do if you're going to go racing.

If it does not touch the gasket surface it should run. The machining seems quite rough if it is not the picture. Was it done on one of those giant beltsander type surfacers?

It's not something I'd care to use on anything where combustion volume was critical and you should make sure there is nothing that can make a hot spot, keep all edges smooth.

On an around town mom's car that will never see more than 5,000 rpm or so it is unliky to be a problem.

[...]The machining seems quite rough if it is not the picture.[...]

It looks rough to me, too, if the photo isn't misleading. Whether that's a problem might be dependent on the head gasket being used; multi-layer steel type usually requires a fairly low average surface roughness (Ra).

 

I found some links that have good general info on the topic, although not all of it is relevant to Subarus:

http://www.aa1car.com/library/ar996.htm

http://www.aa1car.com/library/ic697.htm

http://www.motor.com/article.asp?article_ID=572

-I would grab a head gasket and make sure the damage doesn't affect the metal ring seal.

 

-Then I would compare it to the other head to make sure the machine shop didn't surface the head too deep. This will mess up your compression ratio and possibly the cam timing. Not to mention, make the head prone to warpage.

 

If those checks are good, I would take a die grinder or dremel and lightly blend the chips around the edges of the combustion chamber and run it. I wouldn't be too worried about hot spots and knocking unless you are building this as a competition engine. I've done a lot heads that had foreign object damage much worse than this and were still able to win races.

 

Of course a new head would be better but what about $$$???