Thread: Tappets and timing?

Following on from my fuel pump thread, and taking the advice given here, I'm going to check the tappets and fuel pump timing before playing with the pump any more.

Tappets I'm going to try myself - do I need any special tools, and is this as pretty much as for any other OHV engine?

With the fuel pump, is this really a job for a mechanic who has done it many times before? If it is DIY, so I need anything special?

Tappets on the 300tdi easy to play with (1/2 inch ring spanner / decent screwdriver), but a set of cranked feeler gauges makes it easier. It's hard to turn the engine over without removing the glowplugs ( a worthwhile suggestion) but it can be done using a socket on the crank pulley bolt.

The timing of the injection pump is a little harder. First you'll need to lock off the crank at the flywheel. There is a LR tool and most times a 5mm drill suffices. I had a M12 x fine thread HT bolt machined with a 5mm wide x 5mm long spigot on the end, and I find it easy to wind into the wading plug hole ( Manual trans) and I can use it to set the timing and remove/replace the crank bolt.

Then, behind the AC tensioner, the hole for the timing requires some finesse. You can't directly look at it, but an inspection mirror can aid you. Again, most people use a 9mm drill. The receptacle in actual pump is 3/8th, and the hole in the adjustable plate is 1/2 inch. I have successfully used a M12 drill with the reduced shank, (after smoothing it off with emery paper and wrapping the sharp edges with tape) to set the pump to zero. To get some advance, I went back to a 9mm drill, and rotated against the resistance of the pump. It's only an adjustment of 1.5mm in rotation, but my disco seems to like it ( 10.5L/100l city).

To measure the 'lift' (quoted at 1.54mm, or 1.6 modified) - requires a dial guage and special tool inserted at the rear of the pump. That might qualify for a visit to a diesel mechanic, as it's sort of fiddley even with the correct tool. Remember, a mechanic who specialises in VW or Ford diesels will know as a tdi has the same sort of Bosch VE injection as a VW golf of the same age - and maybe that of a Transit van too.