W126 short body OM606

K26-2

42

06-25-2018, 08:43 PM #1

Hello diesel fans.

I have been browsing this forum for quite some time and figure it is time to give back with some information about my latest Mercedes project.

Here I will document the build of a replacement for my current daily driver, a 1983 W126 with om617. That car's chassis has in the neighborhood of 700k miles and has seen abuse no other car could handle. I initially started refreshing that body but have continued to find more and more damage that isn't worth the time to restore, so decided to find a good example generation II short body. I'll make another thread someday about the build I did in 2005 on the '83, but for now I'll focus on the new car. I found a 1991 350SD which had a blown engine and excellent interior with minor paintwork needs, then drove 2600 miles to pick it up.

The car will have the following specs:
7.5mm Dieselmeken pump
BW S200 from the DPUK guys
722.6 from S55
2.46 LSD

Here it is after loading with come-along in Portland, ready for the journey back. Towing Jeep has a om642/722.6 and rear airbags so was not a problem capacity wise:

[Image: 20180206090705.jpg]

However, along the way the trailer blew two tires at different times in the trip:

[Image: 20180208110421.jpg]

Then I get close to home and run through the carwash to get all of the magnesium chloride off, very excited to get home:

[Image: 20180208155828.jpg]

Shortly after leaving the carwash I look in my rear view and see a shower of sparks and smoke once again...
[Image: 20180208173727.jpg]

This time it had to get a flatbed ride on a medium truck the rest of the way home, rental trailer rusted out leaf spring shackles couldn't take any more. Car was right at the rated weight of that trailer.

Here it is with the '83:

[Image: DSC03956.jpg]

Here is the unmolested interior, best w126 I have seen in awhile:
[Image: 20180520144911.jpg]

I started stripping down the old car, here are photos of the original configuration of the IP in case anybody ever needs to see that:
[Image: 20180211151331.jpg]

And the stripped om603 with it's replacement:
[Image: 20180312181227.jpg]

I sent the mechanical pump off to Dieselmeken for 7.5mm rebuild:
[Image: 20180220115554.jpg]

The OM603 suffered failure from the oil pan baffle washers being ingested by the oil pump.

Here you can see the impacts on the oil pump gears and washer:
[Image: DSC03959.jpg]

This sheared the oil pump sprocket bolt in half, and blew out the front of the timing cover:
[Image: 20180213081958.jpg]

The previous owner said they shut it down immediately, but not soon enough:
[Image: 20180508092400.jpg]

Damage was worst from front to rear of the crank. Pistons were trashed, no reason to try and save this engine.
[Image: 20180507202054.jpg]

I have been collecting parts from the junkyard for the W126 build for the last 15 years or so, and had originally selected a 2002 S500 transmission since the output flange is the same dimension as the one on the 350SD driveshaft.

I have piles of W126 crap that needs to be sorted one of these years:
[Image: 20170808124149.jpg]

About the time I got the S500 and 722.3 transmissions out of storage I happened across a 2002 S55 in the pull it yourself yard:
[Image: 20180311140859.jpg]

I grabbed the transmission and a few other goodies, including the S320 alternator and transmission cooler lines from the W140 in the picture:
[Image: 20180311172050.jpg]

I'll find out in the near future how that AMG muffler flows with the OM606.

I think the OM606 may have come from a flood car, I picked it up in Houston after the hurricane for very cheap. The only problem I found was heavy corrosion in the injector wells.

I cut a tarp and sandblasted the wells in a similar fashion to intake valve cleaning on the BMW diesels:
[Image: 20180429163733.jpg]

The lines kept the media out of the injectors.

Once the corrosion was removed, I pulled the injectors and sent them out for rebuild with 150 bar pop pressure. This left cleaning the carbon out of the glow plug and injector holes:
[Image: 20180501113823.jpg]

Scotch pad on a shaft:
[Image: 20180501142914.jpg]

I ground down some drill bits to use to clean out the injector holes (by hand), they worked perfectly in place of a reamer.
[Image: 20180501111326.jpg]

I tapped out the water pump housing for the bypass hose:
[Image: 20180415131709.jpg]

There was some additional drilling and tapping needed for the older style RPM sensor. This is a 18mm drill hole size for the sensor, and I used m6x1 for the attaching screw:
[Image: 20180517111057.jpg]

More to come soon...

WSchotty