Advice fitting out OM616 short block
 

Thanks to fellow forum member Squiggledog I became aware of an unusual posting on the Tacoma craigslist: the owner of a machine shop that had gone out of business two years ago was selling a rebuilt OM616 short block plus cylinder head that a customer had left behind. My 240D engine runs well, but is pretty long in the tooth (compression cold 250-300 psi, compression warm 300-350). Last weekend I made the trip to buy it.

The machine shop was Waterhouse Motors. Their web site is still up, but all that is left is a room full of stock rebuilt short blocks (all gassers as far as I could tell, and mostly domestic). If anybody is looking for a domestic short block and interested in his phone number, PM me.

He said that they didn't do many Mercedes diesels, which I took as a bit of a red flag, so I've taken the whole collection to Bearing Service here in Portland for measurement and evaluation... hopefully they won't find anything disastrous.

What I supposedly have is a rebored block with new oversize pistons and rings. Crank ground 0.010 undersize. New bearings. I think at least one connecting rod is new, as there was an extra one left in the box o' parts. New timing chain, not installed. Valves ground and re-installed.

So, obviously there is an engine swap in the not too distant future. Obviously I could probably pull my existing engine, put the two engines on stands side by side and start moving stuff over. However, I think that I would rather keep my 240D in running as long as possible before doing the switchover.

My plan is to acquire the essential pieces that should be replaced or rebuilt and have Bearing service build it up into a pretty complete long block. I'd like them to oversee the most critical issues; one of them is getting the timing chain installed so that valves, pistons, and injection pump are all in sync. I think the second most critical issue is likely the sealing between the upper oil pan and the block, and if I can lay my hands on an upper oil pan (uh, Charlie?) I'll have them do that, too.

I should probably also tell you that my 240D is not some sort of show car or a restoration project. I'd just like to have it a really solid daily driver with a good engine that will go another 150k miles.
So, on to my questions...

#1 question:
- I'm looking at a '80 240D with 150K miles at the PicknPull as a donor car for some of this stuff. The block casting of my new engine has an 82 below the casting number, which sort of implies that it is an 1982? Does it seem likely that things like vacuum pump, injection pump, oil pump, camshaft and camshaft towers from this donor will just bolt on and work fine?

other questions
- are 616 engines susceptible to the failure where the vacuum pump can blow up and spew bearings into the timing chain? If so, that would argue for a completely new vacuum pump, no? $350, yikes.
- how important is it to send an injection pump out for inspection and service? The one in the car now seems to work fine.
- I don't have an oil pump assembly for the new engine. Are there specific parts within the oil pump that can be replaced for like-new operation, or does the whole assembly have to be purchased new?
- water pump: I think I looked one up on Fastlane and it was around $55; it's probably a good idea to replace this while the engine is out, right?

I'll have a bunch of procedural questions later, but these are the fitting out questions. Thanks for your advice...

Kurt

Great shop. But they do charge $80/hr for their work.

oil pump - replace whole unit if needed

any vacuum pump can fail.... its just a matter of maintenance. They can usually be inspected for play / wear. If any signs are the slightest bit unusual, replace it.

injection pumps cost $200 just to test. I think most of us should do it, but can not justify the cost.... its ok to cut this corner if the engine runs well.

I am almost entirely certain that the block in question is from a w123 240D.

If so, all those parts will interchange and cooperate.

the bearings on the crank you can check with plastigauge.

if a rod was swapped out, that most likely means that the shop inspected them and did not like this one, rather than bend it back into 'straight'.

Check the rod in the box to see if there is any visible damage to it.

Your 79 has the large Glow Plugs, right? I know my 80 240 has the small pencil GP.

The 240 in the yard should have the small GP. pull the head off of it for your new eng build up. have it worked over, and build up the new engine, then do the swap with all new parts.
if you aren`t in a hurry and the 79 is running good/ok take your time and build it up right. good winter project.

That 150K mile 240 in the yard could be a good engine, never know. too bad you can`t do a compression check on them. They are about $257 out the door here in calif.

I do have an upper oil pan, but at the moment it`s still being used :D.

Charlie

Hi Kurt,

If I were you I would look for a good donor car. The little things that seem to be just a few dollars (or euros) quickly mount up to be a lot. If you can find a good donor then it will hopefully involve more cleaning and refitting than replacing with yet more bits that you've had to source separately. Looking for parts costs time, effort, and money.

If I were you I would inspect what ever you have and then make a decision concerning whether you are going to change vacuum pumps and water pumps. Get hold of a copy of a FSM - clean and measure bits before you buy replacements for your replacements!

The first thing I would do though is get some very fine wire wool 0000 grade say and rub that surface rust off of the mating surfaces on your new block and get it oiled up. DO NOT RUB TOO HARD - you don't want to remove any detectable amounts of metal - some kipper had attacked the head on my engine with a wire brush (that's not good)...

...You need to preserve what you've got - this project might take longer than you think - you don't want to have to pay for some machining on top of your future costs.