Blown Head—how to repair?

[McSpooney]

Originally Posted by Gilles

McSpooney, I found the picture of my beaner shade tree mechanic tool, it is actually a 2x4 but it was strong and stable enough to lower and raise the engine/gearbox assy.

The treaded rod allows you to fine tune the position, if I remember correctly, I put a bit of anti seize on the treads to make it work pretty smooth.. :-)

PS:Sorry for the picture not sure what happen... :-(

Beautiful! I was going to ask what part of the motor you hooked it up to, but I get it now

[BYprodriver]

Originally Posted by McSpooney

Welp. Thanks for the advice guys. Yeah I'm expecting to replace the head. If anybody has a 4-5-6 head laying around PM me!

I had already started preparing to pull the head in place. I figure that I've got nothing to lose. I if the head doesn't come off cleanly, I'll just slap back on what I need to and switch to pulling the engine. I'll post an update on how it works out. For the next sad sap.

I suspect that the problem will be removing the tappet cradle from the head... maybe there probably won't be enough space to get it out bc the chassis is right there. Everything else seems doable. Already have intake and exhausts off. Can set cam timing. Maybe torquing the head will be very awkward from down there too.

Much better to remove from the bottom.

[NewArt]

Funny, I actually have the cross beam piece of equipment that I've used several times when dropping these engines. Glad to know that a 2x4 would suffice! :chicken:

[McSpooney]

Quick update: I called hoffman machine and let me say, I'm glad I did. They clearly have plenty of experience with these cars, and they were super helpful. Len? gave lots of info and plenty of background on the crack rates among the various 996/986 heads.

There seems to be a lot to it, but it looks like my head is likely cracked in a location that is not repairable, and not visible from the outside. I never had any mixing of fluids, and the coolant was pumping out of the exhaust. These are two symptoms that that it was a crack between the coolant jacket and the secondary air injection hole. To verify this, I would need to remove the exhaust manifold and pressurize the coolant system and look for weeping from the hole that feeds the secondary air injection system across the head. Unfortunately, I didn't do exactly that. I had pressurized the system, then pulled the manifold, but didn't re-pressurize after to verify that the leak was coming from that hole. This seems to be a rare failure mode that only affects a few motors... I would recommend talking to hoffman if you find yourself in my shoes!

End result, I have to buy a new head. I'll give you guys another update once I've got a new head in-hand!

[McSpooney]

So... I never posted a resolution to this, because life got busy I guess, even with this coronavirus nonsense. Anyway this was a long saga. Not because I was pulling the head out while it was still in the car, just because I was so busy and the head I ordered off of ebay was broken when I received it, so I looked all over for another head... ended up using a 987 head . Anyway, I'll post my learnings for anybody else who attempts this:

• The whole job is easily done with the engine in the car. Not having pulled an engine in this car before, I would probably only recommend it if you are tight on space like me. If I blow another head, I would probably do it again. For me that's been working on cars for years now as a hobby. It wasn't hard. I can imagine some people would have a harder time though.
• If you are going to do this job, completely remove the cross braces underneath the engine, and a couple of the braces under the transmission.
• It is essential that you do this, to get the head thru that space. Raising the new head into place is a gentle thing that you need a buddy for. My buddy helped me raise it into place and hold it in place while I got a few head bolts thru.
• One thing I was always concerned about was cleanliness. It was much harder to keep things clean and lubricated while I was working under there. I would maybe take some time to clean the area before even getting started next time, as some of my fuel rail/harness was shedding dirt the whole time over the head install area.
• Setting up the cams is way easier than the service manual makes it seem, but be very careful and follow it to a T. And if you have an underdrive pulley... good luck to you. More notes about that at the end of the post.
• I undid 1 transmission mount on my side of interest and used an engine support bar over the top of the engine bay to lower the engine a bit... this helped, but really only got me maybe... 3/4". The engine can't be lowered too much before it runs into stuff. I could have tried harder to get it lower, but 3/4" just barely worked.
• the only thing that fouls when trying to install/uninstall is the head bolts. They are ungodly long and run into the chassis. This is why you have to lower the engine. Because maybe only 3 of them need help going in. It can also probably be done if you pre-place the bolts in the head as you raise the whole thing into place. I didn't try this, but could have maybe not lowered the engine.
• You also have to unbolt the brake lines from the chassis and bend them out of the way, undo this little breather on the bottom of the airbox. So that the bolts clear.
• Torquing the head bolts per factory service manual specs is easy. Even working in the car like that. I just used a 1/2" torque angle adapter. My little set of 12 pt german socket things is all in 3/8" drive, so I adapted from 1/2" to 3/8" and that adapter got me the perfect length so that the torque angle adapter had space to do its thing.
• My car is a 2003, so it actually has the m96.24 engine. I used an m96.26 (987) head lol. Big risk I took, but I believe its fine in the end. The cars use the same valves, same size cams (although I re-used my own cams), and absolutely everything that bolts to/thru the head is the same. Except. Except for one thing--the oil pump on the 987 has a different bolt pattern to it. I think porsche probably had a lot of failed engines because people kept installing the pump backwards, so the mounting screws are now poke-yoke. One mounting screw is offset... so I just reused my old pump and installed 3 out of 4 screws lol. I mean I'm a mechanical engineer and just saying that o-ring compression force for that thin little o-ring can't be more than 10-20 pounds, so the whole thing can probably be mounted with 2/4 screws and if they are torqued properly, shouldn't back out. So I just ran with it.

Anyway, that's it. If anybody has a question on this in the future, just let me know. I'm always willing to help. I've driven the car maybe 5 times and it isn't leaking, runs really strongly. Except for the following:

I am getting a misfire code. I will check it later this week to make sure the harness connectors are on properly for everything, but I expect that I have to redo the cam timing... I have an underdrive pulley, so I think not having the proper pulley may have made my timing job a little too far from the other bank. My durametric says one bank has a cam deviation of -2 and the bank I redid has a cam deviation of 5.8. So I'm expecting to go under there and undo the cams, and move the engine till the two banks are perfectly even. If anybody has advice on this, lmk. I may start another thread to ask questions.

[Robert986]

Originally Posted by McSpooney

So... I never posted a resolution to this, because life got busy I guess, even with this coronavirus nonsense. Anyway this was a long saga. Not because I was pulling the head out while it was still in the car, just because I was so busy and the head I ordered off of ebay was broken when I received it, so I looked all over for another head... ended up using a 987 head . Anyway, I'll post my learnings for anybody else who attempts this:

• The whole job is easily done with the engine in the car. Not having pulled an engine in this car before, I would probably only recommend it if you are tight on space like me. If I blow another head, I would probably do it again. For me that's been working on cars for years now as a hobby. It wasn't hard. I can imagine some people would have a harder time though.
• If you are going to do this job, completely remove the cross braces underneath the engine, and a couple of the braces under the transmission.
• It is essential that you do this, to get the head thru that space. Raising the new head into place is a gentle thing that you need a buddy for. My buddy helped me raise it into place and hold it in place while I got a few head bolts thru.
• One thing I was always concerned about was cleanliness. It was much harder to keep things clean and lubricated while I was working under there. I would maybe take some time to clean the area before even getting started next time, as some of my fuel rail/harness was shedding dirt the whole time over the head install area.
• Setting up the cams is way easier than the service manual makes it seem, but be very careful and follow it to a T. And if you have an underdrive pulley... good luck to you. More notes about that at the end of the post.
• I undid 1 transmission mount on my side of interest and used an engine support bar over the top of the engine bay to lower the engine a bit... this helped, but really only got me maybe... 3/4". The engine can't be lowered too much before it runs into stuff. I could have tried harder to get it lower, but 3/4" just barely worked.
• the only thing that fouls when trying to install/uninstall is the head bolts. They are ungodly long and run into the chassis. This is why you have to lower the engine. Because maybe only 3 of them need help going in. It can also probably be done if you pre-place the bolts in the head as you raise the whole thing into place. I didn't try this, but could have maybe not lowered the engine.
• You also have to unbolt the brake lines from the chassis and bend them out of the way, undo this little breather on the bottom of the airbox. So that the bolts clear.
• Torquing the head bolts per factory service manual specs is easy. Even working in the car like that. I just used a 1/2" torque angle adapter. My little set of 12 pt german socket things is all in 3/8" drive, so I adapted from 1/2" to 3/8" and that adapter got me the perfect length so that the torque angle adapter had space to do its thing.
• My car is a 2003, so it actually has the m96.24 engine. I used an m96.26 (987) head lol. Big risk I took, but I believe its fine in the end. The cars use the same valves, same size cams (although I re-used my own cams), and absolutely everything that bolts to/thru the head is the same. Except. Except for one thing--the oil pump on the 987 has a different bolt pattern to it. I think porsche probably had a lot of failed engines because people kept installing the pump backwards, so the mounting screws are now poke-yoke. One mounting screw is offset... so I just reused my old pump and installed 3 out of 4 screws lol. I mean I'm a mechanical engineer and just saying that o-ring compression force for that thin little o-ring can't be more than 10-20 pounds, so the whole thing can probably be mounted with 2/4 screws and if they are torqued properly, shouldn't back out. So I just ran with it.

Anyway, that's it. If anybody has a question on this in the future, just let me know. I'm always willing to help. I've driven the car maybe 5 times and it isn't leaking, runs really strongly. Except for the following:

I am getting a misfire code. I will check it later this week to make sure the harness connectors are on properly for everything, but I expect that I have to redo the cam timing... I have an underdrive pulley, so I think not having the proper pulley may have made my timing job a little too far from the other bank. My durametric says one bank has a cam deviation of -2 and the bank I redid has a cam deviation of 5.8. So I'm expecting to go under there and undo the cams, and move the engine till the two banks are perfectly even. If anybody has advice on this, lmk. I may start another thread to ask questions.

Glad it worked out for you, thanks a lot for the write up!