More Tips on Case Assembly

[randywebb]

I just helped a friend put together his case halves (small 2.2L motor) and thought this post might be helpful to the next people who are doing this for the first time.

1. You definitely need 2 people or even 3 people. If you are used to doing VW/Bus/912 motors by yourself, this will be almost impossible for you without help. My guess is that even pros who do a lot of these would probably use a helper. You will need some space for the 3rd person (We didn’t really have space in his garage for a 3rd person anyway). This is a lot more stressful than building up a BMW motor. And remember, you have only a set amount of time to do everything correctly because the sealants on the case halves will not wait…

He used these 4 sealants to do this motor…




We did the Yamabond last, and the non-drying silicone first.

[randywebb]

2. Be sure that everyone has well-defined roles – that means they know specifically exactly what they are going to do when. Next, go through at least one rehearsal, just like you were in a play or going to run football or basketball plays – complete with blocking (who moves where, when) if the space is small or has trim or hoses, etc. hanging down where somebody might hit it with their head when standing on one side of the case – just an example – check your own setup.

The person who owns the motor is the lead – they bear the risk of a blown up motor if something goes wrong. If they are not the most experienced person there then they might want to delegate the lead to somebody else. Get it clear on liability before you end a friendship though…
-- not an issue here, just something that occurs to me.


3. Wayne’s book refers to 22 nuts and washers on the case. The missing 22nd nut/washer goes on a bolt, not on a stud.

Here is what people spend their time doing if they are looking for a stud to put the nut on instead…






Here is the hole where nut 22 and its bolt really go…

[randywebb]

4. Have spare seals, nuts and washers available, but keep them is a separate container so you don’t start wondering whether you have too many left over or something. And write down a count beforehand.

5. Define terms beforehand. For example, if you are on opposite side of the case, you can’t say “left” or “right” w/o saying what that means. I suggest unambiguous terms like nose end, flywheel end, etc.

6. Use a Sharpie felt tip marker to mark BOTH halves of the case with the torque sequence for the through bolts beforehand – 1,2,3…13 (for the 11 through bolts and 2 studs that have to be torqued). This will make it easy for the people on each side of the case to quickly do the tightening without constantly referring back to the book for each bolt and stud. The view in Wayne’s book is the inverse of the factory manual. Note that the bolts appear to surround a particular cylinder spigot on one side of the case, but on the other side they will be split between two spigots.

7. The 3rd person could take pics with a digital camera at various times – e.g. before putting in the oil pump (“Did I really put in all the seals?” – then you’d be able to check before running the motor).

8. Have an extra socket and wrenches for the #2 or #3 person to snug down the nuts with. This will speed up the case assembly. Ratchet wrenches are handy for the nuts in the flywheel cavity. Generally, don’t just lay out the tools you need to DO the job; also lay out the tools to redo it after you screw something up (e.g. needle nose pliers so you can bend the oil pump tabs the right way after you peened them down the wrong way)

9. Think about which of the different sealants (we used 4 different ones, with each case half getting 3 of the 4) are slowest curing and which are fastest. After you put Moly assembly paste on the bearings, you then put on the slowest sealants. The fastest setting sealant should go on last. Two people can work simultaneously, 1 on each case half.



Maybe these tips are already out there somewhere, but my friend – a former BMW mechanic – had read Wayne’s book, the factory manual and lots of other sources, and these were things we came up with Post-op as errors or Lessons Learned that would make it easier for others or for us next time (though given the longevity of the 911 motor, it’s unlikely either of use will rebuild our motors in our lifetimes). I also don’t recall these things from Jerry Woods engine rebuild class I took about 8 years ago. So I hope they are helpful to others.

This process is very similar to doing a surgery…

I can't follow my best tip -- that is to make all your friends rebuild their engines first. You can watch or help and learn a lot. This only works if you live in a place big enough to have a fair number of 911 owners. Going thru it is better than Wayne's book, better than the Bentley Manual, better than Jerry Wood's class, etc.

[Zeke]

Good info. Thanks.

[Scott Clarke]

Randy did a great job summarizing our experience yesterday. Just a few adjustments: the motor is a 2.5, not 2.2, and the slowest drying sealant used was Curil-T (non-drying, actually).

I should also add that Wayne was clear about the 22nd nut being attached to a bolt and not a stud. I caught this as soon as I was done. I can't imagine doing this job for the first time without Wayne's book. You can't re-read the section on case sealing enough times. There are a lot of steps that happen in critical sequence under the pressure of time. It took 55 minutes from the moment the first 574 and Yamabond were applied until all fasteners had been torqued and double checked. That being said, I think we were relatively well organized and rehearsed. I'm not sure I could reduce the time much if I did it again today.

I'm very glad that I have done this job for the first time for the last time. Thanks to Randy for his help. Don't try this job alone!

-Scott

[herman maire]

Awsome Randy
Really like the idea of marking the torque specs on the case, so simple yet so brilliant heh,heh.

I will need this list in a month or two for my 3.6 .
I still have yet to get wayne's book...There out of stock.

[CBRacerX]

Good post! Should be moved to Engine Rebuilding Forum.

[Wayne 962]

Originally posted by CBRacerX
Good post! Should be moved to Engine Rebuilding Forum.

Good tips, glad to see that the book is correct. For first-time assemblers, I suppose the more people around the better. However, if you have done this at least once, it's pretty easy to do with only one person...

I'll copy this to the Engine Rebuild forum as well...

-Wayne

[kirkf]

Marking the torque order on the case sounds like a good idea.

My mistake was not having the through bolts fully prepped with lubed O-rings already on them.
I can't imagine how one person could put those case halves together. I suppose practice makes perfect.

Kirk