Timing chain woes...how screwed am I?

[M42Technik]

The timing chain deflection wheel literally just sheared right off the lower timing case. How on earth could that have happened? Because of this it nearly punched a hole in the lower timing cover.

So guys, how screwed am I?

And do I have to remove the entire head of the motor to get the lower timing case off? I know that answer is probably yes, but I just want to hear a "no" so I can get this off easier.

FUDGE.

[monty23psk]

You can remove the lower cover off but it is a real pain to reinstall with head install. Doable and bmwm42 just did it. Did you valves bend? If so, then head needs to come off.

[M42Technik]

You can remove the lower cover off but it is a real pain to reinstall with head install. Doable and bmwm42 just did it. Did you valves bend? If so, then head needs to come off.

I'm not sure if there was any damage to the valves, but the exhaust camshaft was off by a tooth on the chain. So there may have been some interference. I did not do a compression test.

I am considering replacing the engine altogether. This is killing me.

[DesktopDave]

Get an M44 timing case.  It eliminates the M42 idler wheel entirely and has updated guide rails & tensioner.  You need a new one regardless, go with the improved parts.  They're also more common than the M42 bits.

[M42Technik]

Get an M44 timing case.  It eliminates the M42 idler wheel entirely and has updated guide rails & tensioner.  You need a new one regardless, go with the improved parts.  They're also more common than the M42 bits.

I've already purchased the guide rails and tensioner. The guide rails I got looked to be updated in design. Are these the M44 ones? I will look into getting a new case. Will an M42 chain work as well? I don't want to have to purchase all new parts.

Anyone have a good howto on getting the head off? I really don't want to take the damn thing off, but hopefully it isn't too difficult.

[M42Technik]

Looks like the guide rails and some other various bits are M44 case specific, but the chain is not.

In the sake of saving money, I'll have to stick to the M42 design and continue by starting to remove the head of the motor.

How on earth do I keep the camshafts in their proper place? Agh. This turned into a full rebuild now

[blalor]

My idler sprocket lost its bearings and let the chain slip several teeth. Bent all my intake valves.  I ended up finding another engine with 145k miles on it from someone on r3vlimited for $300.  I replaced all of the timing components (sprockets, chain, tensioner, guides, etc.) a few months later for another $500 or so.  If any of the valves are bent, I'd suggest just getting another complete engine.  I was quoted several hundred dollars just to have the head rebuilt.

As for the cams, use the tool to lock the flywheel at TDC (I have one you can borrow, or look on eBay; $15 or so).  Then do this:

Read this in some thread and I'm trying it out.  Seems like it works fine.

Put a crescent wrench on each cam square, cross the handles and clamp with some vise grips.  I put some blue threadlocker on the wrenches for good measure.

I wrapped some rubberized shelf liner around the wrench handles to keep them from slipping.

[rjcaptsean]

Gotta piece of Hardwood and a chisel?  The only addition I would make is if you were leaving the head in the car, drill a hole in the wood and get a bolt to secure it to the rear bolt hole for the valve cover.

[M42Technik]

Well I have a cam lock tool on the car. I'll just ziptie the chain to the sprockets when I take the head out of the car.

I unfortunately have no means to rebuild this engine, nor purchase an entirely new one to replace it. Hypothetically speaking, if I were to find bent valves, what would the repercussions be if I continued to drive on it like that?

[monty23psk]

Rough idle and running, mpg goes way down, wear out engine faster. Cat and o2 will eventually go.

[bmwman91]

You can replace the timing case with the head on. It is a pain in the ass, but totally doable. You need some silicone grease/assembly lube (rubber-safe) and 0.005" or thinner brass shim stock (at least as long as the profile gasket, maybe 3-4" wide). Grease both sides of the shim & use it to slide the case/profile gasket under the head & some longer M6/M8/M10 bolts to pull it on. The real trick is getting the oil pump gear aligned with the crank snout...but it isn't too bad either. Then pull the shim out carefully with vise-grips (pull small amounts at each side & the middle to get it out evenly).

Why did the casting break off? Did the idler wheel seize? I know where you are at man. My oil pump ate a piece of timing chain back in 2005 & blew the timing case up. It sucks, and is a lot of work. Clean everything with a toothbrush, brillo pad & some mineral spirits & then rinse with hot water. Reassemble with the paper gaskets & non-curing high-temp gasket sealer & you will be golden. The motor should stay really nice & clean. Get the spray-on stuff, it goes on thinner & more evenly. Be sure to let it dry for 3-5 minutes before installation.

[rac3r]

I had the exact same thing happen to me, except the idler pulley stayed in place long enough to limp home. Thankfully, the chain didn't slip. I replaced the timing case without removing the head by dropping the oil pans instead of pulling the head, using the procedures described in this forum and the Bentley manual. However, it sounds like you have bent valves and need to pull the head anyways.

As for the alignment of the sprockets in relation to the camshafts, if you have the camshafts locked at TDC for cylinder 1, the arrows on the sprockets should point up, perpendicular to the mating surface of the valve cover. Check to make sure the 4 fasteners holding each sprocket onto the camshaft are centered within the slot, and you should be good to go.