The om642 bluetec weekend project

[argon3030]

Hello diesel people, wanted to share my experience with repairing our bluetec. It has been marking its territory with increasing volume, so it was time to take corrective action. Apparently Mercedes used gaskets of an inferior material for the oil cooler, which after some miles and years will result in an oily mess all over the engine, and give the entire underbody a solid winter rustproofing layer. Making matters worse, they buried the oil cooler as deep as they could. What I expected to take a few hours, ended up taking the entire weekend. A full day of disassembly, and another full day of cleaning and reassembly. Wow I sure hope the mystical powers of these magic purple seals don't wear out any time soon. I would not like to perform this job a second time.


The resources I found most helpful as a first-timer performing this job:

• A journey into the the infamous Om642 oil cooler leak!
• https://www.youtube.com/watch?v=l1IslZzL3vU

A few notes, based on a number of discussion threads and youtube videos:

• Definitely replace the EGR cooler seals while you're in there. One small o-ring, one larger o-ring, and one gasket.
• Replace swirl motor if yours is in-op as mine was. I also made a poncho for the new one, out of aluminum foil, to prevent oil intrusion.
• Good time to replace the water pump, belt, tensioner, rollers. I used a genuine pump from the dealer at over $200 as I've heard the aftermarket pumps use lower quality bearings, that's why they cost so much less.
• Check your right side intercooler hose for crack/leak in the rubber near the upper collar. Mine had a crack and pin-hole leak there.
• I read some folks like to remove the firewall heat shields for more access to the turbo fasteners. I did not, and did not find it necessary. There is plenty of access, nice straight shot to all of them.
• I wish I had found the aftermarket aluminum intake flap arms. I didn't discover these until afterwards. idparts dot com sells them, to replace the brittle plastic ones with.
• I replaced the entire oil cooler with a new one, not just the seals. Not sure this is necessary, but I didn't want to take the chance that the cooler itself had some kind of failure.
• I'm now a fan of these external torx fasteners! The sockets really grip the fastener well, the chances of slipping and rounding one off seems much reduced with these.
• Also now a fan of the fuel line hose clamps. People in the youtube videos pry them off like savages and replace them with inferior worm drive clamps. These factory ones are re-usable and the correct tool allows them to be very quickly and easily opened and closed.

I think thats about it for random thoughts on this job. Nothing really technically difficult, just a lot of steps, very time consuming. I also pulled all the glow plugs since the access was good. I cleaned and lubed them. Hylomar on the body and copper anti-seize on the threads. They all still work, but they're original, just wanted to ensure easy removal when they do require replacing.


Cheers