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In Reply to: Re: Who's Pulled a 750 Head? I Need Shortcuts. :&g posted by Jim Derrig on January 14, 2001 at 23:05:24:
Greetings BMW owners.
Trying to pull the cylinder heads with the Bentley Manual. Man am I lost. One look at those intake manifold assemblies and I'm saying, "how in the world do you get to the bolts on the bottom?" Anyone here got some tricks up their sleeves? Next will be the actual head removal.
Yes I did search the archive.
TIA,
Dave
I just finished doing this on both sides of my 93 750 (see my posting re why head bolts fail). There are no real "short cuts" and yes, its a son of a bitch. Here is some advice:
1. for each subassembly (e.g., throttle bodies, intake manifold) put the nuts and bolts in a labeled plastic sandwich bag. If you don't you'll quickly lose track of what-went-where.
2. when you pull all the wiring harness connections, make a diagram of the connections, so you can remember where to put them back.
3. to remove the intake manifold, start with cyl 7-12 bank. Use a long 1/4" drive socket extention with a 10mm universal joint driver on the end. They come out easier than you'd think. this manifold can be pulled out even thought the other one is still attached. the 1-6 then is breeze.
4. the hardest bolts are the ones on the back of the motor holding the cooling pipe. If bentley doesn't have a diagram showing location, let me know and I'll send you a pic I have. you can't see most of them and have to know where they are (also, see below).
5. you absolutely have to have an inspection mirror to see some bolts, especially on the exhaust manifolds and the cooling pipe
6. you cannot survive without the special tool set for aligning the cams and the crank. It consists of a dowel pin which inserts in the flywheel and two keys which locate the cams. don't even try without them, and degreeing the cams is a breeze with them.
7. megaparts.com is good for prices and can get you oem gasket sets.
8. if your v12 was made after 4/90, disregard the stuff about how many holes are supposed to be in your head gasket for identification purposes. This is old advice that wasn't dropped from the manuals. Just get the "standard" gasket.
9. You absolutely MUST follow with great precision the spec for torqing the head bolts by degrees (22 foot pounds, then 60 degrees then 60 again) You will need to purchase a "torque angle degree" tool. KD tools and Snap-on both make one. The KD one I got was only $35 and eventually got the job done, but I suspect he $80 snap-on is a better piece (the KD slipped until I modified it).
10. To simplify reinstallation, I used grade 8 bolts with stainless steel lock washers for the lower holes of the exhaust manifolds. You'll need to disconnect the manifolds at the first connection (in front of the cats) in order to move them into position on the heads.
well, that's it for now. good luck.
All of the above is great advice. Also, the front timing cover was not addressed and is rather diffilcult. Be wary of some hidden bolts that hold the inner cover (one bolt is located outside the cover!).
Also, I disagree with statement number 6. You absolutely can reposition the camshaft and gear without the special tools...just take care to "punch" position reference marks for both the camshaft and gear. I used a chisel to mark across the bearing journal/cap to the camshaft. You will however need to buy the TDC crank locking arbor to ensure the engine is at #1TDC and stays there.
I would figure about 18 - 20 hours for disassembly and reassembly not counting any parts clean-up or bench time.
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