Here's Karl having a look through the crankcase for any water leaking.  We had to carefully examine the inside of the liners as well as the mating surfaces between the heads and the block.

While not strictly mechanical, I will put the little item in here so as not to lose the continuity of the project.  9010 was originally equipped with a National Safety Appliance Company's Automatic Train Stop (ATS) system.  The most visible part of this apparatus was the "Duplex Magnet Control Valve" that hung under the front end of the locomotive.  We have been kicking this around for years but have never found good photographs of the valve or better yet, a complete valve.  I decided to fabricate something that would give an idea of what the device looked like and our resident forensicologist, Bob Zenk, created the plans.    Much of the layout and piece work was done at the home shop during the virus lock down.  The following photographs were taken of the creative process.

The next job on the Maybach would be reinstalling all of the piston and rod assemblies.  Here is fork rod assembly #9 all taken apart for cleaning.  New oil control rings will be installed on the piston before installation.  The rod bolts have splines as do the rod nuts.  The nuts and washers must be put back on the bolts from which they came so the nuts are stamped with numbers that correspond with locations on the rod caps.  After this one is in place, the #1 blade rod will be next on the list.

Here is piston/blade rod #1 which is the mating assembly for #9.  The piston pin is removed to clean and lubricate the pin, piston and rod..  Having the pin out and the piston off of the rod makes it easier to install the bottom oil control ring without scratching the piston.  The last photo is of the peg board I used to keep track of the rod nuts and washers.

This is a photo of the underside of a piston top.  The lettering shows that the piston was purchased from MAHLE GmbH, one of the largest automotive suppliers in the world.  Even a diversified manufacturer like Maybach could not produce everything.  Second photo is looking down into a cylinder that has yet to receive the blade rod.  The light ring is caused by a camera flash.  And here is some guy celebrating the last piston to be installed.

After all of the pistons and rod assemblies were in, the next step would have been to tighten the rod bolts but we could not do this because we were waiting for some special wrenches.  That process will be covered later.  We turned to dealing with the "crush rings".  The Maybach does not use a head gasket as such.  It has a copper coated cast iron ring that sits in a groove between the cylinder liner and the block.  The depth of each of the 16 grooves had to be measured and recorded.  Once all of them were measured, crush rings of the proper thickness could be chosen.  One at a time, the proper ring was installed in a groove, the head installed and a measurement taken of the distance between the head and the block, at all 4 surfaces - front, left, back and right.  This distance had to be between .003" and .005".  Once the measurement was noted, the head was partially torqued down and the measurement repeated.  As long as the distance did not compress to less than .003", all was good.  We were very fortunate that all 16 of the measurements fell within the normal bounds of a 4.4mm (.173") thick crush ring. We had a selection of rings to use for test thanks to our crew member Rob Fern from the UK.    All of this measuring work resulted in the chart seen in photo #3.

-- Update August 12, 2020 --
Karl has been busy with a project on the engine crankcase.  There are 16 inspection doors, one for each cylinder.  These doors and their studs have been a source of oil leaks.  Karl is removing all 16 studs from each door opening, cleaning the studs, cleaning the holes and then putting the studs back using a good thread sealer.  While the studs are out of the block, he has cleaned the sealing surface of the old gasket material.  The door are getting a much needed bead blasting and then paint on the outside and a coat of Glyptal on the inside.  Hopefully, we will eliminate the oil leaks that used to affect the doors.
With the arrival of the long handled connecting rod bolt tools, we were able to start tightening the bolts.  These bolt are not tightened to a torque  specification but rather to a measurement of stretch.  At the factory, a technician would mount the rod with its bearing and caps in a vise.  The nuts would be tightened while watching an instrument that was measuring the amount each bolt stretched under tension.  When the proper amount of stretch was achieved, the end of the rod bolt and nut were marked with a sort of chisel.  Our challenge was to return those marks to their proper alignment on each bolt and nut combination.   The first thing to do was put ink marks on the notches in the nuts and bolts so the notches would be easier to see.  The 4th photo shows one of the wrenches on the serrated nut.  In this case, the other wrench would be holding the rod bolt from the other side of the block while one of us tightens the nut.  Needless to say, getting photos of this operation was difficult.  The wrenches are used to tighten the rod bolt nuts on one side of the rod while our "T" handle wrenches are used to tighten the other nuts.  In an ideal situation, the engine block would be mounted in a rotisserie engine stand which would hold the block straight up in the air and one could use the "T" handle wrenches on all of the rod bolts and nuts.  Karl worked on the left side while I worked on the right.  We came up with a system that works quite well.

-- Update December 12, 2020 --
With all of the rod bolts tightened, we were able to clean out the lower part of the block and re-install the oil pan.  Karl took on the job of cleaning the gasket surface on the block and putting the oil pickups back on.  When this work was done,  I put all of the windage trays back on.  This completed our work on the lower part of the engine block so we turned our attention to the oil pan.
 Preparing the pan included wiping it out with mineral spirits and while doing so, I noticed a drip or 2 on the shop floor.  An examination of the pan bottom revealed that there were 2 corroded areas in the metal and several spots where the metal had rotted all the way through.  How the pan did not leak oil is a mystery but there were probably chunks of crud plugging the holes.  I made   an attempt  to braze the bad areas but this was not successful due to cracking of the base material.  Karl is seen cleaning the base metal before I made patches and MIG welded them over the entire corroded areas.  Submerging the areas in water for several hours with no leaking proved the repair.

Karl cleaned the top edge of the pan, applied a coat of Permatex #2 and we put the pan back in place.  All 88 pan nuts were torqued and we turned our attention to the side covers.  Karl had previously cleaned all of the covers and block gasket surfaces.  All of the studs were removed, cleaned and reinstalled with sealer as the studs penetrate into the inside of the block and many were seen to have been leaking.  New gaskets were applied with the covers and the nuts properly torqued.

Bill has been working on the exaust elbows.  He cleaned them all, and applied new sealing rings to the sealing inserts.  These inserts go up into the bottom of the turbochargers and are intended to provide an exhaust gas seal.