Timing chain noise/crankshaft will not fully rotate - Update: Success! mostly...

[evbrad2002]

Learning, Learning, Learning!  So, I went ahead and pulled the cams off to ensure that I wouldn't bang on the valves while getting the crank bolt off per your suggestion DesktopDave's. The cam gears actually looked good. Teeth had nice flat tops.  Cams came off without a hitch following the technique outlined in the video you referenced,Mabeer.   Was able to starter bump the crank bolt free, drained the oil per bmwman91' and was happy to find no bearings or shavings present. Finally after fussing with the compressor/bracket was able to pull the lower cover.  The idler sprocket was intact, all bearings present as the oil check suggested.  I found eight different loose pieces of the driver's side chain guide in the case and the lower chain guide was broken in the middle. 

Now, before I pony up for timing kit parts, I've got to look further in to the M44 case update option.  Hope to find a link or two with guidance and a parts list (anyone have one handy?).

More importantly, before I spend any money on timing case, I need to assess my valves.  If they're damaged, may have cry uncle and let a shop take it from here.  I know I should have done a compression test before breaking things down, but getting the chain bound up as I was trying to assess alignment at TDC took that option off the table.  At this point with the cams off, is my best bet to blow some compressed air into each plug socket?  5-10psi? Unfortunately my tools are limited so will have to borrow a tester from a local parts place.  Any other ways to assess valve status at this stage? 

Again, thanks for all of your help.  I wouldn't have made the progess I've made thus far without it.

[bmwman91]

Phew, well it is good to know that you got it safely apart.

I am not sure how much out of alignment things can get with a blown-up driver's side guide. The M42 makes a distinctive "diesel engine" sound when the timing is off and valves are kissing pistons. The engine is remarkably tolerant of that. Back in 2004 I did my first timing case job on the M42 and managed to get things off by a couple of teeth. Being young, dumb and impatient, I thought it was lifters not pumping up and went for a few miles of spirited driving. Got back, fixed the timing and it was good for another 80k miles, until the idler sprocket snapped off (unrelated). If your son didn't hear a constant diesel sound and it just ran poorly, then the valves are almost guaranteed to be fine.

For the M44 timing case swap, I THINK that you only need the M44 timing case, M44 oil pump gears and a custom bracket to hold the crank sensor in place. Metric Mechanic should be able to sell you one, I think. The timing case (with oil pump gears still in it) should be had for $100 or less used on a forum. I picked up one for about that much. A little cleaning and elbow grease and it's as good as new, and no stupid idler sprocket. You should also replace all of the oil pressure relief stuff (parts 5-8): http://www.realoem.com/bmw/showparts.do?model=CG73&mospid=47506&btnr=11_1120&hg=11&fg=30

[evbrad2002]

Have begun the hunt for a late M42 or M44 case.  Will update as I have more and will try to compile a little DIY/parts list when (if) I get that far and don't cave and just go with a refresh of the existing case to get this daily back on the road as soon as possible...of course, I may have it back off the road in a couple months with a disintegrated sprocket/casing like others of you have experienced and be kicking myself....

[evbrad2002]

Well, this is turning into a big adventure...

Good news: did a leakdown test and got 8-10% on each cylinder on a cold engine.

Bad news:  dropped the oil pan after reading about the pan bolts....found 5 in the pan, and the one remaining bolt had backed out a couple of threads...holy canoli!

Wait, it gets better:  also found an alarming amount of plastic and metal bits from the disintegrated timing chain guide lodged in the oil pick up; together with the bolts rumbling around down there, I'm thinking, ruh-roh, oil starvation, but just don't know how much over how much time.

And it gets better still:  pulled the oil filter housing off to do the gasket while all is apart and found an impressive amount of sparklies in the oil...need to filter some out to better check the color but I'm afraid of bearing damage, of course.  Already have all the timing case rebuild parts here or on the way. 

Would sure appreciate some guidance at this juncture.  Is there any way I can assess for bearing damage without pulling more things apart?  Is there any degree of bearing damage that still allows for a serviceable motor for daily driving?  I'm already in to new territory, so pulling heads, replacing bearings or rebuilt blocks, etc. is way out there for my experience level, though eager to learn...the problem is the need to get a daily back on the road sooner than later.   Perhaps I should shop for a tested used M42 and have the fresh timing parts installed before having the engine dropped in?  Thoughts, advice welcome and appreciated.

Update: So, I'm guardedly optimistic after further inspection.  The particles appear to be primarily silver in color, though I did see a very few that appeared copper.  Very difficult to discern at first due to amber color of oil and reflections in sunlight.  When I took a closer look at the busted up chain guide I saw at least one area that had clearly been milled by the chain and noted some copper colored metal used in the guide construction, which you can see in the attachment...also included a fun pic of the guide pieces-parts in the attachment. 

I also confirmed with my son that the oil pressure light never came on.  So, I'm hoping the particles are from the milled guide rail rather than a bearing, but, WOW!, that oil pain and oil pick up looked scary, so still not sure about the bearings.

[bmwman91]

You are probably fine. The chain has a tendency to gnaw on the aluminum stuff in the timing case. When my idler sprocket snapped off, my oil was FULL of aluminum shavings. Just do not get any debris into the round hole that the filter housing plugs into. If the oil light never came on, you are probably OK. There is a rather notorious issue with the lousy thrust bearing that these motors originally had (only half of a shell), so that may or may not be chewed up. You can usually tell how messed up it is by measuring the crank's end play. You might be able to pull the upper pan and do a visual on it too.

It looks like this engine had the original timing components in it. The main guide rail (driver's side) was updated to an all plastic one in the mid-1990's.

[DesktopDave]

Well, this is turning into a big adventure...

Good news: did a leakdown test and got 8-10% on each cylinder on a cold engine.

Bad news:  dropped the oil pan after reading about the pan bolts....found 5 in the pan, and the one remaining bolt had backed out a couple of threads...holy canoli!

Wait, it gets better:  also found an alarming amount of plastic and metal bits from the disintegrated timing chain guide lodged in the oil pick up; together with the bolts rumbling around down there, I'm thinking, ruh-roh, oil starvation, but just don't know how much over how much time.

And it gets better still:  pulled the oil filter housing off to do the gasket while all is apart and found an impressive amount of sparklies in the oil...need to filter some out to better check the color but I'm afraid of bearing damage, of course.  Already have all the timing case rebuild parts here or on the way. 

Would sure appreciate some guidance at this juncture.  Is there any way I can assess for bearing damage without pulling more things apart?  Is there any degree of bearing damage that still allows for a serviceable motor for daily driving?  I'm already in to new territory, so pulling heads, replacing bearings or rebuilt blocks, etc. is way out there for my experience level, though eager to learn...the problem is the need to get a daily back on the road sooner than later.   Perhaps I should shop for a tested used M42 and have the fresh timing parts installed before having the engine dropped in?  Thoughts, advice welcome and appreciated.

These engines are tough little things, unless they overheat.  I think you're good, and it's good to hear about what seems like you're heading toward a happy ending.

I'd suggest a used oil analysis to verify wear metals in your used oil, if you're concerned.  I'm a big fan of UOAs.  They tend to really put my mind at ease, and they're less than $30 ($25+shipping).  I've always been very happy with the used oil analysis at Blackstone - their service is excellent.  Sample collection kits are free if you request them.  If you do send them a sample, be sure to note how it was collected.  They recommend a sample directly from the sump, but if that's not available they'll compensate their tests to suit your collection method.

There are other labs out there too, but I have no experience with them. 

[evbrad2002]

Encouraging feedback.  I'm going to go forward expecting the best at this point; again, it's all a learning process and I really enjoy the heck out of this stuff, so if I end up with bigger problems, I'll have still learned a ton in the process.  The oil analysis is a great idea.  I may have already tainted it beyond a valid analysis, but will look into it.  I continue to find little bits of plastic debris in the little nooks and crannies of the timing case.  Also found some small bits in the oil filter housing.  It's definitely important to comb through several times to ensure it's all out of there.

Funny, my idler sprocket is fully intact, spins smoothly and has only the tiniest bit of play in it.  I know it's not ideal, but after reading the timing case replacement posts and having difficulty sourcing an M44 or newer M42 case for a reasonable price, I decided to keep the existing set up and replace the feared sprocket along with the other bits.  Pray for me

I've got the upper oil pan bolts threadlocked and back in place (still need to check on the others that can be accessed through the bell housing), and the oil filter housing back on with fresh gasket (+ sealant) and o-ring.  Hope to make some more progress tomorrow, but still waiting for some key parts so, with my schedule, I'm still a good week out before having it buttoned back up and putting it to the test.  I'm moving pretty slowly trying to clean things up a bit along the way, and getting the old gasket material off is painstakingly slow when you don't have the little bristle brush drill attachment (does this really work without marring up the surfaces?).  Still have to get the cams back on as well and have some trepidation about getting the timing back in order....have been reading as much about this as possible, including the very helpful threads on this forum, so I think I'm going to be okay.

Again, all of your helpful input has been most appreciated.  I'm sure I'll have more questions as I continue on.

[evbrad2002]

So it's about time to get my camshafts back in (I may have some separate questions about this later) and I wanted to get some input on the best approach to take at this point to get things timed back up without bumping valves and pistons. I have read a great deal on this forum and others but a couple of points I'm not confident about in my situation.  Below are the steps I have in mind; please correct, clarify or make suggestions where necessary:

Before replacing cams, turn crank to about 270 degrees past TDC (the point of alignment of oil filter housing arrow with mark in crank tooth).  This will put the pistons in the midway position across all cylinders for the last time prior to reaching TDC at 360 degrees.  This will allow me to install the cams at the "sweet spot" (where load is only on cam at cylinder one, valves will be open) referred to in the Pelican Parts article and, once installed, I should be able to turn them to TDC without bumping valves on pistons.

Once cams are at TDC (I plan to lock in place with rigid metal rule with C-clamps at rear squares), I should then be able to rotate the crankshaft the final 90 degrees to TDC without bumping valves.   I don't have stock flywheel so have no holes to lock crank at TDC....suggestions? I do plan to confirm crank TDC using the 81mm measurement between cylinders 1 and 2.  But not sure how to ensure that it stays in place as I install and tension chain.

From here I'll pretty much be following Brendan Purcell's DIY.

Any input welcome and appreciated.

Thanks!

[bmwman91]

I always use the 81mm measurement technique. There is a fair bit of friction from the rings holding things in place. Once you get things in phase and reassembled, carefully turn the crank a few revolutions manually and then re-check that the cams are still where they need to be with an 81mm difference between 1 & 2. Hopefully there's not massive carbon build-up on the piston crowns or it could make that measurement a little tricky!

[evbrad2002]

Well, I've got it all back together and it's essentially running very well.  The 81mm technique was a lifesaver in the process of getting timing together.  Again, my thanks to the helpful input provided along the way.  The only flies in the ointment are:

1) I've been fighting the dreaded idle gremlins since getting back up and running.  I got the AFM code (1215, as I recall). Was initially getting the crazy rapid surging or high idle with rythmic drops. Now after reseating and snugging up a few fittings things seem to be better, but I'm still getting high rpm idle (2kish) at cold start at times and then, either on its own, or after a quick restart, idle will drop down low briefly to near stall and then settle in to a healthy range.  Once going, it runs like a champ; pulls strong.  I've sprayed around a bit with brake cleaner and so far have not found any clear signs of vacuum leaks. Any suggestions of likely sources of idle issues after doing the timing chain?

2) I noticed the first couple of days some white smoke coming out of the exhaust with a bit of water collecting at the tail pipe.  Bleeding was a real PITA; temp kept creeping up past mid point at extended idle, so a bit concerned about my head gasket.  Hoping its just moisture/condensation from sitting a bit and coolish mornings in the always humid south, but the smoke seemed heavier than I recall seeing before and did have a rich (maybe sweet?) smell to it.   Haven't noticed it smoking the last couple of days but the exhaust still smells a little funny to me and still seeing some moisture collecting/dripping from exhaust.  May just be being paranoid...?

[bmwman91]

1) Could be a sticky idle control valve. Clean it out thoroughly with TB cleaner.

2) Could be normal water vapor at start up and you are just paying more attention than usual.