[bmw] M30 cylinder head R and Ramblings

["David A. Leonard" <dleonar1@xxxxxxxxxxxx>]

>>Any
assistance from the group on this head fix welcomed and greatly
appreciated.
>

John, I did my cylinder head at 141,000 miles(cam r and r ), then again 
when I lost the gasket at 225,000 on my 88 735i.

The first time I removed the head with manifolds(major pain unhooking fuel 
rail and little injector clips/harness), the second time, following the 
advice of the dealer mechanic that I had recently bought a 1/2 hour lap 
dance at the local strip club (best $20.00 I ever spent)  I undid the 
intake manifold from the head, and left it in the car.  This meant that I 
didn't need to unhook throttle, cruise control, Fuel injectors, and a 
variety of other time consuming items to unhook, break, and re 
install..Much easier.. like 6 hours easier!  The head was a lot lighter 
without the intake on it as well, I was able to install it without using a 
hoist the second time, solo.

I used stock head gaskets both times, there is a minimum head thickness 
that needs to be observed.. if you don't mill the head much in 
reconditioning, you don't need the thick head gasket.

The first time I did the head and cam, and I took the whole thing to the 
local NAPA machine shop, where they did a valve job, and changed and 
reassembled the head for me.  I have personally done a 2002 head cam 
reassembly, and it is a fiddly process trying to hold the valves down while 
you install the cam..it was a lot easier to give the shop the $300 or so it 
cost and let them do all the work.

A trick I have heard for installing the cam is to use one of those KD lever 
valve compressors, and block the valves open with little pieces of wood to 
hold the rockers up to get the cam in.  The rocker shafts have cutouts for 
the head bolts, so they need to be properly clocked on reassembly, or the 
head bolts won't go in.

My dealer buddy told me that he has seen a lot of people bend valves in a 
head replacement.

Be very careful to have all the pistons at the midpoint of their travel 
when you reinstall the head, then they can't bend the open valves. You can 
then roll the engine up to #1 and #6   at TDC with the cam at  #1 cyl both 
valves closed(both cam lobes  pointing directly away from the rockers) and 
reinstall the cam sprocket and chain, and tensioner.    I'd say it took me 
about 20 hrs to do the whole job the second time.

I used a wire brush and a grinder to decarbonize the pistons, taped off the 
other jugs to keep the crud out.
Make up a piece of plywood with 2x4's on it for a skid to hold the open 
valves away from the skid, and securely fasten the head to it for 
transportation so you don't bend the valves in transit.

AT 141k the valves were  ground, and the valve stem seals were new, the 
next time the shop just cleaned and vacuum checked the head, and gave it 
back to me stating that all was perfect and it wasn't necessary to do the 
valves.  The head gasket set that Bavarian auto sells is pretty good 
<www.bavauto.com >, I think Elwing makes it, the same as OEM according to 
the dealer guy when he looked it over.  I think that was about $160.00

The Bentley manual (I used the 535i manual, same motor) states that the cam 
sprocket timing mark needs to be at 12:00...well it is straight up relative 
to the engine, but these are slant six motors, and it is 12:00 relative to 
engine centerline, but not relative to the installation in the car(more 
like 1:30)..took me a few tries to get that right.

My dealer buddy doesn't use the two stage torquing recommended, he goes to 
70 ft lbs with pretty good luck.  Dan Patzer says to retorque..and I agree 
with him.  I found the firewall end two bolts to need a lot more retorque, 
in fact since that is where the head gasket blew, I would guess that the 
design lends itself to moving there more.   By the way, did you have one 
steam cleaned spark plug? mine was a very clean #6 plug due to the coolant 
leak.

Well, off the top of my head, this is about all I can remember, I hope this 
helps.  Remember to use new copper washers on the cam oil spray bar, and 
remember to install it so the holes line up with the cam lobes, and loctite 
the banjo bolts so they don't back out.

I like to roll the engine over a few times manually with the plugs out so I 
can make sure the valves and the pistons aren't going to smash into each 
other and wreck my day!  better to find out this way than when you turn it 
over with the starter!  If memory serves(check before you try)  I think pin 
11 on the diagnostic plug is the one which will allow you to use a remote 
starter switch to turn the starter without ignition..very useful when 
setting up the valve train.  I use a paper clip in the plug pin hole, and 
get 12v from the remote battery lug under the hood.

Hope this helps

Dave Leonard
88 735i w 252k miles, and a new British Racing Green paint job(DIY! in the 
garage) It still runs as strong as the day I bought it, and the tranny had 
no gunk in it when I just changed the filter!
91 325ic (about to journey to the airplane hangar for hibernation)
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