Difficult case separation. What worked for me.

[Brett San diego]

This is reposted from a thread I've been running over on rennlist. When I searched here for some assistance with separating my case, I found only one thread on a difficult to separate case when I searched "case separation," so I thought I'd post my experience here, too, for any other's benefit. I'm no expert. This is my first engine teardown, so I don't know if these techniques are expert "sanctioned," but it is what worked for me. The engine is a 1978 911SC 3.0 L.

The case should not be this difficult to separate according to what others have told me and what I've read. My engine has apparently been apart before due to a catastrophic failure (possibly on track) as the 911 was tracked by the first owner. So, it apparently got put back together with some pretty good glue. Whatever it is, it is dark brown/red in appearance and fairly hard and brittle now. So here goes...

I made an attempt at splitting my case this evening, an unsuccessful attempt. I even welded together a spreader tool to apply tension between the fan housing mounts. Then, I tapped and tapped and tapped harder and tapped harder and pounded pretty good with a hammer on a wooden dowel set against the case, and... nothing. I'm off to do some forum searching.

Here's my spreader tool. I didn't see one of these available on Pelican Parts, so I had to make my own. LOL


So here's the rest of the story of splitting my case. I searched on the Pelicanparts 911 engine building forum, and surprisingly to me, I only found one thread on a difficult to separate case when searching "case separation," but it was helpful.

My case does not want to separate

Basically, the guy ended up doing the same thing I was working on, getting creative with spreading tools.

After initially failing with my spreader tool between the fan housing mounts, I decided to tackle spreading the lower side of the rear of the engine between the engine mount studs. Given that the case mating surface is broken up by a couple of large openings (crank shaft pulley and intermediate shaft), it looked like it should be a more weakly bonded area.

Here is a pic of the spreader in place. Just a couple pieces of old bed frame angle iron with nuts welded to one side and some wood to pad the threads on the studs.



I cinched and cinched the thing down expecting the spreader to fly out of place anytime. I decided to take a break for a second and think about banging on the case with hammer and dowel again, and there was a snap sound. Damn, I thought, there goes the wood. Looked at the wood. It's fine. Maybe, just maybe it's... this.





Yep, that's a split in the case. Eureka. LOL

I then put the spreader back between the fan housing mounts and torqued it down pretty good. Nothing. So, I'm fumbling for the hammer and case beating dowels, and pow! The bond breaks across the top side. Scared the bejesus out of me. I'm thinking I broke something, but all was good.



I even put a little spreader on the breather cover studs to finish off the top side.



I put a couple of nuts on studs on opposite corners of the case to catch the falling case half and rotated the case to use gravity to help out with initial separation.





As things were coming apart, here's reason #1 that I'm glad I split the case.



This washer was floating around the case. You can see it's bent at 90 degrees (already got in the way of something). I thought I was hearing something tinkling around inside as I rotated the case while working on it. This must have been the culprit and would possibly have stayed in there if I hadn't opened things up.

Hope this is informative for anyone out there.

Brett

[CaptainCalf]

Nice work Brett, I'd prolly still be heating and beating on that case with a rubber mallet
RC

[BoxxerSix]

You should be VERY careful pushing on those studs like that. You'd never catch me doing such a thing and for good reason. You can easily break off the case, and it'll cost you alot more for the TIG + machine repairs than the time spent in slowly tapping the case apart the old way. I've repaired numerous cases because of what you pictured above, and/or from people driving against the case perimeter studs.

There were as of last week a couple GT3 cases on ebay with broken casings like this.

There are key areas where you can drive against one side of the case with a wood dowel to get the parting line open, then use wooden or nylon wedges to slowly separate the halves. Cheap plastic door stop wedges, or even plastic log splitting wedges are a cheap DIY tool in a pinch. Both available at just about any hardware store for ~$5.


Glad you got it to separate without breaking, just be cautious in the future with this method.

[Brett San diego]

Originally Posted by BoxxerSix

You should be VERY careful pushing on those studs like that. You'd never catch me doing such a thing and for good reason. You can easily break off the case, and it'll cost you alot more for the TIG + machine repairs than the time spent in slowly tapping the case apart the old way. I've repaired numerous cases because of what you pictured above, and/or from people driving against the case perimeter studs.

There were as of last week a couple GT3 cases on ebay with broken casings like this.

There are key areas where you can drive against one side of the case with a wood dowel to get the parting line open, then use wooden or nylon wedges to slowly separate the halves. Cheap plastic door stop wedges, or even plastic log splitting wedges are a cheap DIY tool in a pinch. Both available at just about any hardware store for ~$5.


Glad you got it to separate without breaking, just be cautious in the future with this method.

I felt I whaled pretty hard on the case with a hammer and wooden dowel (and with a spreader in place between the fan housing mounts) before I gave up and decided to try spreading on the engine mount studs.

Your point is well taken and is the kind of feed back necessary for this thread to be more useful. I am careful to point out my non-expert-ness. I may have dodged a bullet in my naivete. The wedges are a great idea once you have a part started. It's getting that initial part that was the hard part.

The other important lesson for me in this exercise is to be sure to use a more appropriate case sealant.

Brett

[Alan Goettel]

I had one of those days myself last time I tried to split my case. When I had removed that last nut, it got alot easier.

I hate when that happens!

[KTL]

To further add to the discussion, what's the consensus on the sealant that was used here? My guess is somebody chose to use Permatex Form-A-Gasket.

[Tippy]

Originally Posted by Alan Goettel

I had one of those days myself last time I tried to split my case. When I had removed that last nut, it got alot easier.

I hate when that happens!

Believe it or not, that is about 99% of the reason why cases are hard to split!

[jwasbury]

Originally Posted by BoxxerSix

snip...You'd never catch me doing such a thing and for good reason. You can easily break off the case, and it'll cost you alot more for the TIG + machine repairs than the time spent in slowly tapping the case apart the old way.
There are key areas where you can drive against one side of the case with a wood dowel to get the parting line open...snip

That was my thread about case separation that Brett referenced earlier. I can tell you that my case was never going to separate by slowly tapping. Tapping? Hell no, I beat the bejeezus out of my case around the "4 corners" with a wood dowel for at least an hour with no separation of the parting line.

If you bill by the hour and were doing my rebuild using "the old way" for case separation, it would have been the most expensive engine build of all time.

If you bill a flat fee and were doing my rebuild using "the old way" for case separation, it would have been the biggest negative profit engine build of all time.

Brett, the sealant you were dealing with looks like the same stuff I had. Getting the residue off of the mating surface is quite the chore as well...good luck on your rebuild.

[Brett San diego]

Originally Posted by jwasbury

That was my thread about case separation that Brett referenced earlier. I can tell you that my case was never going to separate by slowly tapping. Tapping? Hell no, I beat the bejeezus out of my case around the "4 corners" with a wood dowel for at least an hour with no separation of the parting line.

Yep. My case wasn't going to separate with years of "tapping." I even hit the thing pretty hard with a hammer and metal socket extension directly on the "4 corners" hoping that the high frequency vibrations transferred to the case would help break the bond, but no luck.

I had already tried my spreader between the fan housing mounts before coming across your thread. Your comments encouraged me to keep working with the "spreading tool" approach.

And, yes, I'm not looking forward to the cleaning part.

Brett

[TibetanT]

Very informative discussion about the 78/79 3.0L engine case and problems splitting the case. Mine was the same way...hours of fun splitting the case, as well as the ulcer when it finally 'cracked' loose. My stomach lurched.

What are your plans for cleaning-up the old sealant, or rather ideas what to use to remove the old crap?

Thanks

[TibetanT]

Forgot to mention earlier that I used the tapping method described in Wayne's book and then also poured some Acetone along the parting line to try and soften the sealant.
This engine I am working on had sealant with the same composition as you describe here: hard, red and very dark in places.

[Brett San diego]

Originally Posted by TibetanT

What are your plans for cleaning-up the old sealant, or rather ideas what to use to remove the old crap?

Thanks

I don't know, yet. Start less aggressive and move to more aggressive. I'll probably start with various solvents (acetone, ethyl acetate, dichloromethane, commercial gasket remover) and a scotchbrite pad by hand, then move up to a drill or grinder and scotchbrite wheel, than maybe a brass wire wheel on the drill/grinder.

Jwasbury, still reading? What did you do to clean the case?

Brett

[304065]

Send it to Ollies in Lake Havasu for tumbling and a thorough cleaning and checkout!

Aluminum 901/05 Engine Case Tumble-Polished: Perfection Defined

[Brett San diego]

Originally Posted by 304065

Send it to Ollies in Lake Havasu for tumbling and a thorough cleaning and checkout!

Aluminum 901/05 Engine Case Tumble-Polished: Perfection Defined

Obviously, a great service, and I know they're one of the best. I wish I were local to them. I'm just wondering if it's worth about $200 in shipping to have $200 in work done (assuming it would be around $200 for round trip shipping). I should have mentioned that there is an air-cooled-Porsche-experienced local machine shop that I'm going to investigate. They might have the same cleaning process or something similar. I'll see if they do this kind of case cleaning, or if it would be up to me to deliver a clean case to them.

Brett

[jwasbury]

Originally Posted by Brett San diego

Jwasbury, still reading? What did you do to clean the case?

My case was at the machine shop to bore out the case spigots for 100mm cylinders. While it was there I had them run it through their parts washer. Back at home I attacked the mating surfaces with various solvents, none of which did much of anything to loosen up that sealant. Rubbing alcohol and acetone were the two I reached for the most, but in the end I think it was good old fashion elbow grease and extremely careful usage of a razor blade as a scraper that got the job done. I resealed with Loctite 574.

[BoxxerSix]

I'm not against prying on the case at all to get the surfaces to move, but against those small 6mm studs is just asking for trouble. The positioning in the fan support is great, and pushing against the inner surfaces of the PCV opening are good as well. I can tell you first hand what it costs to TIG repair the snapped studs/broken case as I do them often enough here for people who pry or drop the cases

Also, for those looking for something to strip the sealants off. I use Kleen Strip aircraft paint stripper in 100% concentrate all over the housings prior to putting them in my jet wash machine. The paint stripper is the nuts for cutting through oil/grease, carbon, most sealants, etc, etc and washes off with warm water(even a pressure washer can do the trick. It's now offered in aeresol spray cans now making application in the tight areas of the case and relative housings much easier. Very stubborn sealants I just take a small brass bristle brush to put a light scratch in the surface of the residue and it allows the paint stripper to penetrate the material and lift it.

I used to use industrial type aluminum acids at the shop but the paint stripper works faster/better and is actually cheaper in the long run because I'm not dealaing with hazmat charges anymore


EDIT....also for the "newer" cars with the engines that have that damn german undercoating crap on them(IE 986, 996, etc) the paint stripper eats that crap right off like nobody's business!

[haycait911]

I've been lucky in that patience, a deadblow mallet, sacrificial chunks of wood, and a heat gun have always gotten it there eventually.