Angle for MMO soak
 

Ok last year when I checked cold compression I had only 260 psi in number 5. Since I am planning a vacation I was thinking of soaking number 5 in MMO. Without removing the valve cover I can find TDC and since the firing order is 1,2,4,5,3 5 should be at the bottom of its stroke at 36 degrees. So then just fill it up through the injector nozzle and wait 2 months!

Better yet would anyone know what position is best to fill all the cylinders? May as well do them all I guess. Should I be putting in known volumes of MMO?

Hmm... my math says #5 is at nadir when #1 is at 108* ATDC. The same math says at 36* ATDC #1 you get all the pistons as low as possible. Check oil level before and after to see if a significant amount of MMO leaks past the rings.

Given the cant of a 60x, I wonder if the ring circumference will soak at only 36* ATDC. Roll the right side wheels onto 2x8s to level the deck :)

Sixto
MB-less

Thank you Yes your math is much better. Is 2 oz MMO sufficient for each cylinder? Ambient temperatures will be about -5 degrees C if that matters but I will have no abilities to refill during my absence.

I soaked the rings in my 603 while the head was off. I don't know what the setting of the crank was, but even with the cant, I was able to submerge all 6 cylinders with at least a half inch of MMO above the highest point of the pistons. It took a 16 oz bottle of MMO to fill all 6. But I agree that it would be better to jack up the passenger side in order to get more in there.

Krwsenior do you recall how long it took for th MMO to leak past the rings? I'm thinking without topping up the MMO, rotating the engine and with the cooler temperatures this exercise maybe be worthless perhaps best just to dedicate 2 or 3 days to do the soak?

How will you remove the MMO after the soak?

260psi cold is a GOOD number. Minimum spec is 18bar ( approx 261psi ) hot so it will be within spec when hot. MMO does NOT work unless the coking is very light. BTDT. I took an OM603 cylinder out with stuck rings and soaked it in MMO for a week, nothing. Soaked in solvent, surface coking dissolved, basically nothing. Need to break the ring loose with slight hammering and scraped the coking out by hand. Even this was a lot of hard work. This piston may be the extreme but I do not think MMO works magic as most members believe.

It took a few days, I think about 3. I had a drip pan underneath car to catch it. Be sure to turn the engine over a while without compression in order to push out any residual before starting.

I would turn it over by hand a few cycles then spin it with the starter and catch any spill by rags at the injector holes. Then insert injectors bleed the system and start.

I agree. I don't think it did any good. But won't hurt either.

At those low temperatures no actual chemical action will occur for all practical purposes. Seventy degrees F is the threshold basically. Leaving the block heater connected may get the engine warm enough.

. I just do not know.

Recently, the camshaft on my 603 broke at highway speeds. Pulled the head and took it to the machine shop. The number 3 piston is marked, but not damaged. So while the head was in the shop, I soaked the pistons with MMO as stated in earlier post. Ended up having to pull the pistons in order to hone light scuff marks in number 3 cylinder (honed them all and replaced rings). Found more carbon build up on the piston than normal in number 6 and 1 stuck compression ring. I'm glad now that I went ahead and pulled them. Thus my reason for thinking the MMO didn't do much good.

Thanks I think I'll skip the soak while gone it was just a last minute thought.
I have never heard of a cam breaking on these engines?

I'm still not sure what caused the camshaft to break. I rolled in a new timing chain several months ago. I had driven it for about 5000 miles since that time without incident making several long interstate trips. I had the cruise set on 75 mph about an hour from home when I felt a small thump and the speed fell as if you turned off the key. Luckily I was near an exit and found a wide place to get over. I found a crack in the cam cover so I knew it was bad. Towed home and found the cam gear broken into small pieces and the cam shaft broken just behind the gear location. No damage to the block or crankshaft thankfully. The timing chain is still good also. I'm now waiting on the machine shop to finish with the head. I can only see one valve bent and only have a mark on that piston (number 3). I have another vehicle to drive so I can take my time with this. What I'm most worried about is getting the proper alignment of the cam, crank, and IP when going back together. Buying lots of tools! This is my first time this deep inside a Mercedes diesel. I've printed bunches of instruction from the 126 online service manual.