m42 engine rant

[Bmr]

So after rebuilding my top end and timing components. My after thought is. The paper gaskets for the timing cover frigging suck. Seriously waste of paper. Rvt > paper gaskets.

Lining up camshafts with out the BMW tool is almost impossible, thanks for some write ups I read things went a little smoother. Also valve cover bolt holes. Seriously PO of these need to realize this is aluminum we are bolting into. More than 10lbs tightening going to strip these out. I have to probably tap and die all of mine. Not really looking forward to that. Stupid centering of cam gears is a pain. Not having a pin to hold in, what the heck were you thinking bmw??? Also putting the headers on the head first before putting the head on is so much easier than the other route. Doing so makes the head gasket install a little pain, damn thing kept sliding down.

Other that Its pretty straight forward with using the Bentley manual. Shoot i can probably dissamble the top end of the engine apart now in less than a hour. I do have to say though working on my m20 was so much easier than the m42. haha

/end rant

-brandin

[bmwman91]

Yeah, the paper t-case gaskets are poop. Ultra-Grey RTV all the way.

Getting the camshafts aligned is not TOO terrible for a stock engine. You just need to get the rear square ends parallel, which can be done with a flat metal bar and some large crescent wrenches. As for the pistons at TDC, that's easy with a stock flywheel and an M8 bolt.

Valve cover bolt holes...they just strip, no matter how careful you are. I have helicoil'ed every single one of mine. Speaking of bolt holes that strip, did you already have a plastic chain guide rail (driver's side) in there or did you swap one in with the head rebuild? The newer plastic one uses a 45mm long hex cap screw at the top when the old guide used a 40mm one. A lot of guys have accidentally used the old 40mm long one and stripped the threads in the head.

The HG shouldn't slide around. There are two locating sleeves in the block that would hold it tight in place. There are supposed to be, anyway!

[Bmr]

Yeah, the paper t-case gaskets are poop. Ultra-Grey RTV all the way.

Getting the camshafts aligned is not TOO terrible for a stock engine. You just need to get the rear square ends parallel, which can be done with a flat metal bar and some large crescent wrenches. As for the pistons at TDC, that's easy with a stock flywheel and an M8 bolt.

Exactly what i did. 2 28mm wrenchs lined up after i squared best i could. I did about a dozen times just to make sure. It didnt not want my damn timing to be off. And the hole on the back driver of the bolt to align TDC is ingenious. glad that was there. I also realized my exhaust cam was a degree retarded from the PO. Maybe thats why the valve burnt, no idea though.

Valve cover bolt holes...they just strip, no matter how careful you are. I have helicoil'ed every single one of mine. Speaking of bolt holes that strip, did you already have a plastic chain guide rail (driver's side) in there or did you swap one in with the head rebuild? The newer plastic one uses a 45mm long hex cap screw at the top when the old guide used a 40mm one. A lot of guys have accidentally used the old 40mm long one and stripped the threads in the head.

Figured that about the valve cover bolts. Im going to get a dozen m6x1.00 helicoils this week. I was lucky enough to have a m44 block and head. So i used the bolt from the m44 for my new non metal chain guide. what a difference between old style and new style. I updated to the m44 tensioner also. Funny thing though the bottom timing chain guide passenger bolt hole snapped off while undoing the bolt. I laughed about that. I had some JB weld and luckily it worked. I have a newer back timing cover i will probably put on before i a do build in the future.

The HG shouldn't slide around. There are two locating sleeves in the block that would hold it tight in place. There are supposed to be, anyway!

Oh I know back and front pin. Well when I took the head off, No front pin anywhere to be in sight. And then realized it was in the head. Oh well. Once lined up it wasn't such a pain. The other thing also was the head i had the cam holders were put in backwards. Talk about a pain to get out, I had to remove all the threads.

[wazzu70]

For the cams, spend a few bucks on the locating tool....its worth it!

If you do not have a stock flywheel to use the TDC pin, you can always use the mark on the toothed wheel on the fromt and the arrow on the oil filter housing.

[Dj Buttchug]

i have no idea how you guys have so much trouble setting time. Ive never had any issues with the cams or the crank. Ive also never used the bmw timing tools, hell, I dont even lock my flywheel.

Op you should have dowels on the block to keep the head from sliding around when installing.

for the VC bolts I would consider a stud kit.

[TobyB]

almost all the cam crap for the M42 is just copied from the M52, which IS a bear to
do cams on. The 4 cylinder's not.

Use the E36 M42 gaskets- they're different and a LOT easier to deal with.
Odd shit, but it works.

t

[Bmr]

i have no idea how you guys have so much trouble setting time. Ive never had any issues with the cams or the crank. Ive also never used the bmw timing tools, hell, I dont even lock my flywheel.

Op you should have dowels on the block to keep the head from sliding around when installing.

for the VC bolts I would consider a stud kit.

Its not bad, but just a little pain compared to a m20 which was a breeze to work on and so easy without a Bently. For my first time tearing down this engine and working on a DOHC, I was surprised by the extent of it. Also dowel was stuck in the head that's why. Me not paying attention, lol. Going to send you a PM about turbo engine stuff if that's alright. I have a few questions.

almost all the cam crap for the M42 is just copied from the M52, which IS a bear to
do cams on. The 4 cylinder's not.

Use the E36 M42 gaskets- they're different and a LOT easier to deal with.
Odd shit, but it works.

Heh, makes sense, cam journals and mount is a interesting set up to say the least. Also i have to take the top timing cover to be machined because the damn thing doesn't line up with the block.

[bmwman91]

What is this about having the top timing cover machined? Do you mean that when you place it on, it sits 1-2mm higher than the head where the valve cover bolts on? If so, do NOT have the cover chopped down.

The top timing cover sticks up because you aren't compressing the outer rubber profile gasket. You are supposed to put a couple of upper timing cover bolts in loosely and then use the valve cover to compress it down into place before bolting it down. Here's the right procedure.

- Apply a thin bead of Permatex Ultra Grey RTV in the (cleaned) groove in the top of the lower timing cover, and add a bit of extra in the ends where the front rubber profile gasket will butt up to the inner one.
- Place the outer rubber profile gasket into the RTV'ed groove and seat it by hand.
- Either prepare upper timing cover gaskets or run a thin bead of grey RTV along the upper cover's mating surfaces if skipping the gaskets.
- Place the upper timing cover into position and install 2-3 bolts along vertical-center positions. Finger tighten them until the heads are about 1mm away from the cover.
- Remove the valve cover gaskets from the valve cover.
- Find some large M6 washers.
- Use 2-4 of the thermostat housing bolts and the washers to secure the valve cover into place using the holes in the head nearest to the upper timing cover. Carefully tighten them (rotating between them) until the valve cover has pressed the upper timing cover down and it is flush with the head (you'll notice that some of the bolt holes in the upper timing cover are ovaled...for this reason).
- Install the upper timing cover bolts, starting from the center and working outward. Do NOT tighten them all in the first pass. Get them finger tight, then rotate through all of them 1/4 turn at a time.
- Once the upper timing cover is secured, you can remove the valve cover and install it normally with gaskets.

I know it seems like a lot of work, but it is what it is. Keeping the profile gasket in compression ensures a good vacuum seal and lowers the chances of oil weepage. Make SURE that you put a good amount of RTV into the profile gasket end-butt area or it WILL leak oil.

Also, for the thermostat housing, follow a similar bolt tightening procedure (finger tight, then rotate each one 1/4 turn at a time). You WILL crack the housing if you don't (ask me how I know). Same goes for the oil filter housing, and any interface that involves compressible gaskets.

Here's the general idea:

[Bmr]

Did that still isn't flush. The bolt sit on the top side of the oval. I thought this at first and then realized it isn't that.

[smyleboyd]

YESS!!! thank you bmwman91 for the info. I was was going to post and ask for advice on the timing cover gasket but you covered exactly what i wanted to hear. now im one step closer to putting this damn m42 into my 2002.

[bmwman91]

Did that still isn't flush. The bolt sit on the top side of the oval. I thought this at first and then realized it isn't that.

Something is very odd then. How far above the head does it sit when it is moved all the way downward?

[Bmr]

Something is very odd then. How far above the head does it sit when it is moved all the way downward?

i'll measure when i get home.