Update on the $100 240D - not good
 

Had the day off and figured what better way to spend it than getting the 240 running. I headed out early and was at the car by 10:45, figuring I had a lot of work to do and about 5 hours to do it.

First order of business was the new starter. Piece of cake from above on the 240, only thing I had to do was remove the battery tray and breather. I was able to reach both of the bolts from above too - only had to reach under the car to retreive dropped tools. Starter took me about 45 minutes to R&R.

Once the battery tray was back in I placed the battery, leaving it unconnected. Then I replaced a couple rusted hose clamps at the T-stat housing and headed for the glow plugs. I was able to R&R the glow plugs without having to remove the injector lines but that did require some contorting. Glow plugs too were a snap, no more than 15 minutes. Then I moved on to the fuel filters, got them changed and primed the system.

Only thing I didn't do was drain the old fuel from the IP, in fact I didn't even think about that. Hooked up the battery and was ready to hear the beast run.

Soon as I warmed the GP's and hit the key the engine was turning over nice and fast, much faster than with the old starter, but no joy. Tried it again for a little longer and soon I could hear one cylinder hitting with a "fwump". Tried many times and could only hear the one cylinder hitting.

Dejected I called Roy Hunter (hopefully during lunch) and talked a few things over, I tried a few "tricks" he had and started getting a second cylinder to hit - "fwump, fwump". Man this puppy is gonna start.

Next try I held the key and let her spin. Soon it sounded like it was trying to hit on all cylinders, even started getting smoke out of the tail pipe, but still didn't start. So I waited, then gave it another long spin, it was trying "fwump, fwump, fwump", man I just know it's gonna start. Then all of a sudden the starter quits. I hit the key and the starter just goes clunk.

Just abouyt this time Roy called me back, I explained was happed and told him the starter was too hot to touch. Because of the prolonged cranking it seemed likely the starter had been toasted. I ran into town and tried the local parts house - no they don't have one, but can order it and have it in a day or two. No thank you, that won't work.

I went back to the car with the intention of cleaning up and putting things away when something made me look at the valve cover.

http://www.pe.net/~mktangas/brokevc.jpg

Well, I knew right away that this wasn't good, so I pulled the valve cover. I fully expected to find a broken camshaft, like the many pictures we've seen here before but that wasn't the case.

http://www.pe.net/~mktangas/cam.jpg

cam is intact, but look at the chain.

http://www.pe.net/~mktangas/brkchain.jpg

http://www.pe.net/~mktangas/brklink.jpg

http://www.pe.net/~mktangas/brklink2.jpg

The spocket seems to look okay

http://www.pe.net/~mktangas/camsprkt.jpg

I was able to locate the cam timing marks, with the cam stopping where you see it in the picture

http://www.pe.net/~mktangas/timingmrk.jpg

Alright, so the timing chain broke while trying to start. On the plus side - it happened when trying to start rather then while driving, it happened when the battery was getting tired and the starter getting hot. Maybe, just maybe damage is confined to the chain and guides. I guess I'll have to drag it down here and pull the front cover. Any ideas on a cause, or likely candidates to checkout?

The deal for the car included an extra MB diesel engine, I just don't know which one it is yet. I will finally see it when I go to trailer the car. Maybe I'll get lucky.

Anyways, I'm bummed.

I gotta bad feeling you are gonna find some bent valves. These things are interference engines aren't they? Rebuilt head at least.... Sorry, RT

Just fish the end of the chain up from the bottom and pull a new one in! You may have to pull the bottom pan to get to the end, but first take a look down past the tensioner rail and see if the chain is visible. If so, bend a tiny hook on the end of an unfolded coat hanger, you may get lucky!

Clamp the chain on the cam first...

Peter

Funny you should mention hooking the chain Peter. Roy and I were just on the phone talking about trying that very thing.

While cranking I have to admit that I don't remember looking at the oil gauge so I can't say whether or not it was building pressure. There seems to be an absense of oil on the valve train, which may be a sign of a bad oil pump. Does anyone know if this pump is chain driven on the 240?

The oil pump is driven off the IP drive shaft, so if the chain was broken you didn't get any oil.

If you didn't break a cam tower, you are probably all right enginewise, but a valve clearance check will tell you -- bent valves won't come all the way up.

Peter

In the third picture the third cam lobe seems to
have a crack in it, unless it is oil but it is hard
to see.

Louis.

[QUOTE=MikeTangas]I guess I'll have to drag it down here and pull the front cover. Any ideas on a cause, or likely candidates to checkout?

QUOTE]
I'd guess that something else broke and that's why the chain snapped. It would take some inertia to snap a chain like that, cranking without engine damage wont snap a chain.. This may explain why the dude had and extra engine in the first place!....

These OM's are not like your M117, no front cover, just nasty pita countersunk pins which hold the rails in place.

I'd Drop the pan first and see what's in it.....

My guess:

I do not think the engine siezed because you were able to turn the engine with the starter.

Timing chain guide broke. The pieces fell between the gear and sproket, and broke the chain.

You can put on a new timing chain and see if the engine starts.

I think It'd be worth putting on a chain and trying. It's pumping oil, you can see its' filled the head bolts. Just make sure it's timed correctly.

This is deja-vu all over again for me. In 2001 I broke my 240D timing chain while cranking. The chain tensioner rail had failed allowing the chain way more slack than it could handle. The chain actually wrapped itself around the bottom sprocket, and unfortunately there isn't enough clearance there but for one row of chain. The engine locked and the chain snapped. I had to pull the engine to get the upper oil pan off, which had a good sized hole in it from the chain interference. I then pulled the chain out, changed the bottom sprocket, and installed a new chain. There was no valve, piston or cam bearing damage. The engine locked right before it broke, so I don't think the pistons even had a chance to interfere with the valves.

Mike, you may have a different failure mode, but it sounds just like mine. I'd check the area around the crankshaft seal, to see if the chain wrapped itself around the bottom sprocket....you may see a hole in the upper oil pan in that area, if it did. If it didn't create a hole, you may be able to free the chain by rotating the crankshaft backwards a bit. Otherwise you'll never get it out.

Good luck.

Frankly,

I had a lot of time to think about the failure on the plane today. I kept coming back to the fact that the chain snapped on the tensioner side, and my belief is a hard engine failure would break the chain on the injection pump side, You experience does seem to fit this pattern but unfortunately I won't be able to put eyes on the car for a while. I will definitely check out the upper pan next time I go to the car, plus I will bring my flashlight to try and fish the chain out - even in bright daylight I couldn't see down into the depths.

The tensioner rail, FWIW, was not in contact with the tensioner and was actually a little inboard. I suspected it was because the chain had fallen against the lower end of the rail and levered it inward. Which end of the rail broke on your's, the upper of lower end?

I still think it is salvageable, just have to put a little more work into it. What really bites is that I wanted MY $100 behind the barn story to end with me driving it out of the field and 300 miles home ;).

Mike,

Sorry it has taken so long to respond...I couldn't remember exactly where the chain tensioner rail broke, so I had to go dig it out of a box in my shop this morning. It broke at the pivot point and was kind of just laying in the chain cavity on top of the pivot pin. The tension piston wasn't contacting the rail any longer.

What really caught my eye was the picture and symptoms you have are identical to mine. The chain was wrapped half way around the valve sprocket and broken, and the starter would not turn the engine (engine locked). I think this type of failure could happen with a bad tensioner, also, but I think the chain break and the engine lock are undoubtedly linked. I can't think of any other reason your engine would lock, and even if it did lock, this wouldn't put a lot of force on the chain. I suppose the chain could have broken and then got wrapped around the bottom sprocket, but I have heard many mechanics say that chain breaks usually occur when something else fails first (ie. rails, tensioner, etc.).

Anyway....hope you can get to bottom of the trouble and fix it with a minimal amount of hassle. If it is like my situation, a new chain, sprocket, repairing the oil pan, renting a hoist, and tensioner rail only cost me about $400, and I did the labor with a lot of help from this forum. If your oil pan is okay, you may be able turn the crank backwards to free the chain, fish it out and pull in a new one without pulling the engine.

Good luck!

Frankly,

The symptoms are sounding more consistent with your failure. It will be interesting to see if the tensioner rail is broken at the pivot end, the upper end was a good 1/2 inch or more off the tensioner piston and when I tried to move the rail it didn't move smoothly. I didn't think much of that at the time, because I felt the loose end of chain was laying against the bottom end, now I'm leaning toward that rail breaking.

Again, I feel lucky it happened while trying to start rather than while tooling down the road. I'll be keeping my fingers crossed that the upper pan is intact just to cut out some of the work ;).

Hey! What happened next?
 

Yeah Yeah -- I know I've been MIA...

What ever happened with this story?

Pete

I working on a way to get the car towed/trailered down so I can work on it at my own pace. Don't see that happening though until I return from Mississippi at the end of September.