Unimog 1300L Engine Rebuild/Replacement

Project Report 1998-1999

Posted 20081023

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The Experience

These photos were "lost" for quite awhile until I found them under the wrong folder on the computer. My 1300L Unimog suffered an engine failure and these photos describe the removal of the motor and installation of a brand-new crate motor from Mercedes-Benz in Germany. This effort was big and spanned about 6 months all told. The failure happened in December 1998 and the truck was finally ready to roll the last day of May 1999.

The photos below are what we saw.

The head was taken off the motor while the block was still in the truck. The shot above was taken from underneath the head as it was hanging from the engine hoist.

The head is a beefy chunk of meat. I would hate to have it fall on my foot.

The truck frame, sans engine.

Houston, we have a problem. Note that the #5 and #6 cylinders have deep scars. If you look closely, you can see the crack in the #5 cylinder (the one toward the bottom of the photo) that is in the web between the cylinders. This means either the block needs to be replaced or it needs to be re-sleeved. I opted for a new block.

Kai pulled the engine out. Above, Kathleen inspects the inside of the cylinders.

Kai examines the head. Note the valve cover on the bench at the bottom of the photo.

The ass-end of the motor was dripping oil through the rear main seal. Not a good sign. But, since the block is going to be replaced anyway, it is just making a mess.

The clutch, too, has seen its better days. Soon, it will be off to the shop to be re-done as well.

Note the oil in the bell housing and the scars on the flywheel.

We waited from December to May to get the full set of parts and the correct block as a earlier model, non-turbocharger rated block was first shipped. Note the part number below the machined surface for the air pump.

This is the block after it was first uncrated and unwrapped.

We had the old head inspected and found some cracks which required a new head and the gasket kit as well.

To protect the new motor, a pre-luber was also installed.

The turbocharger was removed and re-built.

The old water pump was deemed serviceable and was therefore used in the new installation.

The turbocharger-rated block has pistons with depressions in the center to improve efficiency.

The piston for the air compressor fits to the cam shaft.

The original equipment belt-driven air compressor was one of the first things to fail on my truck and had been replaced with a cam-actuated, block mounted compressor.

The new head looked nice and clean before the injectors and associated plumbing was installed.

The head is mounted on the block.

A view of the underside of the block, looking up.

The air compressor is now mounted.

Another view of the head after attachment to the block.

Injection pump was then attached followed by the priming pump.

Injectors were installed.

The pan was installed along with the drain line for the pre-luber.

Kathleen assists Kai in getting the harmonic balancer correctly torqued.

A side view of the mostly-completed assembly.

The engine is ready for attachment of the clutch assembly.

Newly rebuilt clutch assembly.

After the clutch and bell housing were added, the engine was taken out for a new paint job.

The cab on the truck was tilted again to allow reinstallation of the completed engine.

The engine hoist did a fine job of lifting and installing the block in the frame.

The front side with belts attached.

In progress, but nearly completed.

Lowering the cab. Note the shift levers on the platform.

The finished product ready for a road test.

Yow!! This was the biggest and most complex mechanical task that I have ever been associated with. Kai did 99.99% of the work and it was done right the first time. I question whether I could have done this task assuming I elected to do so. But, as Clint Eastwood said in "Magnum Force", "....a man's got to know his limitations". True enough.

Thanks to Kai for his hard work and a job well done.

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