06 October 2025:
The Machine Grey CF has sat for a couple of months now, as work focus shifted to other projects that needed to be completed, and then preparation of the M113K V8 Crossfire for the 2025 Crossfire Fall Rally in Helen, GA. There was a lot of last minute work completed on it, and it performed well at the event, turning into a crowd pleaser for those who took rides in it This weekend there was time to work with the "507" engine for the new project. It was the slow, tedious work for removing the front timing cover to gain access to the oil pump drive components. I neglected to take pictures of any of this, unfortunately. The oil pump chain and guides needed to be changed from the C-class type dual sump pump and pan to the S-class type front sump, which is the same style of oil pan and sump setup that the Crossfire uses on its stock M112 engine. The idea was to closely follow what the original setup was, so as to have fewer issues with this conversion. If you have never pulled the front timing cover on one of these, or on a M112/M113, the work is straightforward, but there are many seals that must be replaced, and all of the RTV has to be removed, cleaning all surfaces, and then re-apply. It's slow, messy work, and not the most photogenic work.

After this was completed, attention shifted to the top end. M156 engines are really fantastic, but they have a fatal flaw. That is the camshaft arrangement. In order to keep the valvetrain as lightweight as possible, Mercedes opted for a flat-tappet hydraulic cam follower system. This means that the cam rides directly on a hydraulic lash adjuster that then rides directly on top of the valve. The good news is that this means that the cam geometry is perfectly straight, and with the least possible mass. This guarantees really good high RPM performance. It also means that the cam is riding directly against a metal surface, and that is where the flaw is. The cam is killing itself slowly with every revolution. Eventually the cam and the lash adjuster/follower/cam bucket will eat each other up. Most often the cam is the first casualty. The intake cam, being higher up on the engine, has less oil on this surface, simply due to gravity. The exhaust cam usually has some oil pooling as it sits lower in the engine, and so they tend to last a little longer, but even they will wear out. There are two strategies people employ to help combat this: first is to use LiquiMoly Ceratec additive, and the other is to use the M159 Black Series lash adjusters. These are regular lash adjusters with a diamond coating that makes the lash adjusters both stronger, and smoother, helping the cams to last a little longer. Upon removal of the cams both exhaust cams were found to be in decent shape, but both intake cams were showing some wear. Within limits, but enough that two of the cylinders would have been disadvantaged over the others. Fortunately a full set of reconditioned cams intended for another engine were on the shelf. A full set of Black Series (BS) cam buckets were obtained directly from the MB parts department, and we were off to the races.





They actually have a "pretty" appearance to them in person, and almost pearlescent look to them. Next up was camshaft installation. The M156 uses a unique system to install the cams. The camshafts bolt in, and then are aligned with a special fixture. Typically one bank is done at a time, but we have two fixture tool sets, to be able to line up all four cams at once. The cams are aligned, and then the phasers are installed onto the cams. These are then also aligned with the fixture tools, and once everything is lined up properly, the bolts at the end of the phasers are tightened down, and everything is in time. The timing chain is basically irrelevant to the final timing, unlike the M112 where the whole chain has to be lined up and tensioned perfectly.

The black tools behind the phasers and at the rear of the cams line the cams themselves up here on Bank 2

The this fixture lines up the phaser shutter wheels (that trigger the cam position sensors)

A view of Bank 1with the tools installs. The rear tool is a little more visible here

Here we see the phaser fixture installed on each bank

Once the phaser bolts were torqued down, the fixture tools were all removed, and the engine was rotated several times. Next the engine was turned upside down on the stand, and the upper oil pan surface was prepared, and the oil pans were sent through the parts washer. More on that in the coming days.

p.s.- Going back to the beginning of this update, someone will inevitably comment that the M156 must be hot garbage since it eats the cams. Well, a few things on this. We had one M156 car with nearly 250k on it, and it ran fine. We have a 2015 C63 Edition 1 car in the shop right now being repaired, as it finally ate the cams at about 210k miles. OTOH, people have had them fail at less than 100k miles from too much high revving, not enough oil changes. YMMV.