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.
http://forums.pelicanparts.com/911-engine-rebuilding-forum/500832-my-case-does-not-want-separate-2.html
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