Idle speed

I need help with a couple of issues with my 1980 Mercedes-benz 207D T1 van fitted with the OM616 engine as I'm not overly familiar with diesels, having spent most of my misspent youth fiddling with petrol vehicles.

When I start the van from cold it shakes quite a lot because it seems to tick over too slowly. If I raise the revs slightly with the throttle it doesn't shake quite so much. When the engine has warmed up, it ticks over nicely and doesn’t shake. It feels like it should be revving a bit higher when cold. The only literature I can find is a Peter Russek Manual, but that just states to get a Mercedes dealer to adjust the idle speed. Is there anything I can do myself to adjust it?

The second issue is that I can’t seem to find the fuel filter. I have previously owned a couple of old diesel vans and a Fiat Panda diesel, so I know what I am looking for. Does the van have one fitted? James Robbins

The fuel pump can be adjusted, but it is a delicate system and by altering the idle speed control you may upset the balance of the running. It should actually be recalibrated as opposed to simply adjusted. If you do wish to proceed with this, full details can be found at this website http://bit.ly/1wz2c0n, but please heed the warnings on the website.

The fuel filter should be a spin-on canister, much like an oil filter and it is located at the front of the engine at cylinderhead level on the nearside of the vehicle. A 24mm headed bolt secures the filter to the housing. Many of the 207D vehicles were also fitted with a small plastic in-line pre-filter that's normally found in the fuel line as it runs along the side of the engine from the fuel tank.

It may be the case that, after replacing the fuel filters, your first problem is eliminated, so I would do this before attempting any adjustments to the pump.