Attn OM606 - inspect under the engine cover - PeachParts Mercedes-Benz Forum

jay_bob · #1 07-22-2013, 07:07 PM

Starting with the 606 MB decided to start covering up some of the mechanical bits on top of the engine to give a more streamlined appearance under the hood and probably due to the fact that the injectors are sitting in pockets on top of the head that need to be protected. Well that cover can hide some developing problems as I discovered.

I decided a couple weeks ago to work with greazzer, who happens to live about 2 miles from me, to rebuild my injectors on my 98 E300D.

When I removed the trim cover we discovered several of the injectors swimming in a couple inches of engine oil, the injector hard line clips were missing or broken, and tie wraps used to secure and separate the hard lines instead of the proper clips and spacers.

The valve cover has the usual gasket around the perimeter, and in addition all 6 injector wells have an o-ring. If the o-ring is compromised then lube oil will find its way into the injector well.

I also had a hard line fracture due to lack of proper support. We discovered this when we went to restart the engine after reinstalling the reworked injectors.

The injector line is special order and after waiting 2 weeks, my box finally arrived from Pelican a few days ahead of schedule. During this time the car was inoperable so my wife was very glad to see that box show up...

The repair was fairly straightforward, remove all 6 hard lines, remove the return lines, and remove the 8 bolts holding the valve cover on.

Renew the gasket and the 6 o-rings and bolt the valve cover back on. I used a genuine M-B gasket and it almost seemed too large and kept wanting to jump out of the groove, but after a couple of tries, it set down perfectly.

I then renewed the rubber spacers on the hard line brackets (7 total) and installed the hard lines, including a replacement line for the one that fractured, and secured them with new clips and spacers.

I took the opportunity while I had the IM off to replace the 6 fuel hoses that feed the IP. I thought about just swapping the o-rings but the hoses were very stiff and discolored so I bit the bullet and bought all new hoses. Well I got 5 done, forgot about the crush washers needed for the one hose that is the fuel return from the IP to the filter housing.

I suspect something had started leaking fuel from somewhere, I was starting to get little whiffs of fuel in the engine compartment. Now that smell is gone.

Just a heads up to you fellow 606 owners, have a peek under that cover and avoid some trouble later. Granted this is much easier on a drive by wire turbo 210 than the other 606-equipped cars, no accelerator cable or cross over pipe to mess with on the turbo 210.

shertex · #2 06-22-2015, 05:03 PM

Finally took this off on the the 98 to take a peek. A bit of blackness around the #6 injector well, but otherwise looked fine. I cleaned up the well and will keep an eye on it.

JayBob, your post answered a question I had: Is this cover merely decorative? But I gather it has some sort of protective function as well.

Would it be safe to spray brake cleaner in this area to clean things up? Or is that a bad idea?

pgringo · #3 06-28-2015, 01:52 AM

I'm sure the plastic engine covers are also to reduce engine noise. I have the oem cover on my alh tdi and i ran without it for a day. My wife even noted the louder engine sound inside the car.

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jay_bob · #4 02-02-2019, 11:00 PM

One more thing to add to this thread, there are actually 2 seals per cylinder.
The injector well shield is actually a removable piece.
The seal on top sits in a groove and the valve cover rests on top of it.
There is also a seal in the bottom of the well shield that needs to be replaced.

Once you have removed the injector the well shield pulls straight up. Depending on where the cam is resting, you may have to rotate the engine a fraction of a turn, to get the cam lobes to clear the shield so you can pull it up.

Once you have the shield pulled out, the female end of a 3/8 drive extension is the perfect size to wrap a rag around to clean up the surface where the injector heat shield sits.

83w126 · #5 02-03-2019, 01:05 AM

I have seen at least one story about someone blowing up an om606 due to oil and fuel in that area getting sucked into the crankcase ventilation system and causing a runaway.