What is the break-in procedure for MB diesels? - PeachParts Mercedes-Benz Forum

#1 01-06-2004, 06:33 PM

This is somewhat of a stupid question, but I've never had a new or rebuilt MB diesel engine.
I was just think about this while I was thinking about rebuilding my 617 some day. Is it any different then a gas model, especially with the lower revs.

Just wondering.

Stevo · #2 01-06-2004, 07:05 PM

hotskillet

I rebuilt my 616 last spring in a friends shop just so he could help me out along the way. His procedure was to lub the cylinders with nothing but ATF so the rings will seat properly. When you fire it up run it at different RPMs. Wind it out (not excessively) and let off , Do not hold the same RPMs for extended periods. Change the oil after a couple hundred miles. Anyway this is what I was told and what I did. After 4K the engine uses little oil and runs very well.

leathermang · #3 01-07-2004, 06:07 AM

There is a whole different oil filter that is supposed to be used during the break-in period.
Before starting an engine it should be turned over by the starter long enough to charge it with oil. For this the Glowplugs should be left out . On old regular engines one would use a ' false distributor bottom to connect to the oil pump and drive it with a big drill to charge the oil passages right before installing the distributor.
Piston rings should be coated with ' Assembly Grease" ... typically moly Di sulfide . It is called Assembly grease for a reason.. it will stay on the bearing surface long enough for oil to replace it.

Stevo · #4 01-07-2004, 11:47 AM

Morning Greg

I used that black moly Di sulfide Assembly Grease, it is spoz to stay there and protect things longer than anything else. Aley swore "only put ATF in the cylinders walls, "NO grease on the rings" according to him.

You should be able to access the top of the oil pump drive shaft with a drill motor but I think with things "lathered" up with assembly lub , moving parts are protected untill the oil pressure comes up before she lights off. Anyway that was Aleys procedure.

leathermang · #5 01-07-2004, 12:29 PM

The manual says to use the oil...
But every other internal combustion engine instructions I have seen in 40 years says to use the Assembly Lube..
And it may very well be ok if you are on an assembly line or everything goes just fine in your assembling of the block...
But my assembly goes slower than that by a long shot... for instance... lets say we put the oil on a piston, install it and then go to the next ones... I turn the crank so that the connecting rod cap is on the down stroke... for ease of access... so the first piston installed will likely have several up and down strokes of the crank before the head even starts to get installed...
So the oil control rings are wiping the bore and the oil under normal temperatures is slowly following the beck and call of Gravity... Then there is no telling how long it will take me to get the top of the engine installed... and whatever else I decided to do in the engine compartment before the engine is ready to turn over for the first time... a couple of weeks would not be uncommon for me... and I just don't think there will be much regular oil on the upper rings/bore for those first few ' under power ' strokes...

Stevo · #6 01-07-2004, 12:45 PM

"Then there is no telling how long it will take me to get the top of the engine installed..." Good point. When I did my engine in Aleys shop I did get it all put together in short order as he needed the space., I will find out what he thinks about the "normal" case where its a while before its lit off. I am doing another 616 and I installed the pistons 3 weeks ago and the head is not on yet, maybe today