M117 Fan clutch

The other day I was driving my 560SEL on a fairly hot (30C) day in heavy traffic. The engine temperature got quite warm when sitting in traffic. It was well over 100C in traffic, which would eventually cool down when I got moving. The car didn’t overheat, but I did hear coolant boiling in the radiator hose after I finished the drive.

While the temperature itself is well within spec, given the day wasn’t really that hot compared to days in the mid 40s we get here in Sydney, I wanted to do something about it. Additionally, the air conditioning […]

The M117.968 560 Engine

The 560 is the ultimate M117 engine. This family of engines was introduced in 1969 with the 3.5l M116 and was followed in 1972 with the 4.5 M117. The M117 is a longer stroke version of the M116. Both engines share a SOHC design, 2 valves per cylinder and always had fuel injection.

These engines evolved over time with the final iteration coming between 1985 and 1991. The 560 was the largest M117 engine offered, although to be pedantic it is actually 5.5 litres.

M116M117Fuel InjectionOtherApplications 1969-1975: 3.51972-1975: 4.5D-Jet EFIIron Block, Mechanical valve adjustmentW108, W109, W111, W116, W107 1976-1980: 3.51976:1980: […]

450SLC timing chain check

The Achilles heel of M116 and M117 engined cars is the timing chain. As the engine is an overhead valve engine, the chain is used to make sure the valves open and close when they should. On the V8 the chain needs to go to both heads and down to the crankshaft and so it is very long. This exacerbates the potential problems compared to other engines.

Over time the plastic guides become brittle and the chain stretches. The most likely failure is either due to a stretched chain or brittle guide, the guide breaks and causes the chain to […]