Detroit Diesel Restoration / Dodge Conversion - Page 1
Updated April 18, 2015
First day home, it's a bit of a rusty hulk, but mostly just surface rust. The engine hasn't been run in many years and was stored at a commercial site. First thing on the list is to disassemble it and look for any problems.
Nearly everything originally on the engine when in use is still present. The only obvious parts missing are one of the two stages of fuel filtration and the oil return pipe from the turbocharger back to the oil pan.
Though a little tough looking, everything appears to be in decent condition save for the surface rust. Oil pan still contained a near full load of oil and it was very clean.
The turbo compressor wheel shows signs of debris hits on the leading edges of the vanes, but nothing serious. Most all can be dressed without fear of altering the wheel balance.
Lifting the valve cover exposed the fact that this is one of the 4 valve heads (all exhaust). This was an improvement over the earlier 2 valve version. One rocker arm controls 2 valves with 2 rockers per cylinder. The paired rockers work in unison. The heavier center rocker arms operate the mechanical fuel injectors.
One of the many interesting designs in the engine is the fact the entire valve train, including the cam followers, are mounted in the cylinder head. When placed on the cylinder block where the camshaft is mounted, all the followers are placed in position over the cam. The fuel injector nozzles are placed in the center of each cylinder, spraying a 9 pointed pattern into the concave tops of the pistons.
The plain shaft on the left of the cylinders is the counterbalance shaft. It has counter weights attached at each end, as does the cam shaft, and works in conjunction with the cam shaft to counter the vibrations generated by the vertically reciprocating movement of the pistons and connecting rods. The cam shaft, here installed to the right of the cylinders, operates the followers and valve train in the head. The pistons exhibit their sunken domed tops into which the fuel injectors deliver the fuel.
Unique to this engine, being of the two cycle design, is the array of intake ports located around the middle of the cylinder liners. The cylinder block contains a chamber called an "Air Box" that surrounds these ports of all 4 cylinders. The Air Box is mildly pressurized by use of a Roots type blower, thus supplying the scavenging required of two cycle engines when the pistons travel down the cylinder and expose the ports to the combustion chamber. The turbocharger blowing into the Roots kicks the pressure up to increase the engine's horse power rating.
Another unusual feature of these engines is the fact that the timing gears are located at the back of the engine between the block and flywheel. Also, again because of the two cycle design, the camshaft (and balancer shaft), turn crankshaft speed.
The 'bottom end' of this engine is nothing but heavy duty. 5 main bearings carry the crankshaft while the connecting rod bearings (and wrist pins) are typically massive.
This 85 pound crankshaft has been through a previous rebuild in the past and has been reground .010" under on all bearings. All bearings mic true, round and flat and cleaned up beautifully. The crank is in excellent condition. Anyone familiar with the rod journal layout of a normal 4-banger crank will notice the difference with this crank; again due to the two cycle design.
(UPDATE: During a second inspection, it was found that, even though the crank looked great to begin with, there actually exists a major flaw in the #4 rod journal. At this time, I'm unsure which direction I can take to remedy the problem, but it will be very costly regardless.)
Big time main bearing webs can be seen in the now bare block. The yet to be removed cylinder liners can be seen with their intake ports.
The bare basic block. All 255 pounds of it!
Looking into the cylinder bores, it can be seen that there are 3 separate areas around each liner. The upper most space around the liners is the water jacket used to cool the cylinder liners. The middle section is the Air Box to supply the cylinders with pressurized air for scavenging and combustion. Two high-temp O-rings are placed between these two areas to positively separate the two. The bottom area is mostly a close fit between the bottom of the liner and the block with the crankcase and oil located just below.
A little size comparison of one of the extracted cylinder liners. Also note how the individual port holes are angled in, which will cause a swirling action as the air rushes into the cylinder. This enhances the scavenging action. Only the #3 liner showed signs of cavitation, but this engine will receive all new liners, pistons, wrist pins, rings, bearings, seals, etc. Pretty much the works.
One of the 4 mechanical fuel injectors. All 4 were gummed up and near frozen tight. All have since been disassembled, freed up, cleaned and rebuilt with new internal filters and seals. The Diesel fuel still inside each smelled more like 5 year old gas!
An exploded view of the parts inside one of the injectors. Luckily, there was little to no signs of water inside the units themselves, just a lot of crud and varnish.
The turbocharger has already been completely dismantled and gone through, with a full rebuild kit being applied.
The turbo just prior to re-assembly of the major parts. The center section with the bearings and seals is already completed. The green tube is the newly fabricated oil return line that was noted missing.
The completed turbo temporarily mocked up on the engine to check alignment of the two impeller housings and check the fit of the oil return tube.
The governor and control, fully disassembled with the fuel pump separated from the assembly.
Once cleaned up and checked, the governor is reassembled ready for the addition of the rebuilt fuel pump.
The gear fuel pump will receive a full rebuild kit, including a new shaft, seals and pressure relief valve parts.
The water pump had been reworked at one point, and only needed cleaning up, inspection and new paint.