MK4 TDI timing belt service Part 2

TDI timing belt service continued. Once piston number one TDC is confirmed and the cam and injection pump locked in place, the belt tension can be relieved and finally removed.

Upon inspection of the original belt it's clear the service is timely before belt teeth crack any further and shear off, or worse yet completely snap a belt.

Now we can start on replacing all the components included in the 100 thousand mile service kit, starting with the water pump.

Here we have an original unit with plastic impeller. The bearings are awfully gritty and the o-ring has hardened and aged to brittleness.

We'll let the coolant completely drain and prep the block and sealing surface for the new shiny water pump, which has a metal impeller and new seal. Volkswagen coolant is supposed to last a lifetime but there's no sense in skipping the pump, and for that matter the thermostat and housing, when already this deep in the front of the motor before refilling with fresh coolant.

Next up is the timing belt idler pulley, where the kit includes a new sealed bearing and bolt. This one spins just above the water pump and in fact blocks access to one of the pump mounting bolts.

Further service includes the camshaft front oil seal. It's a lip seal under the forward cam journal bearing cap, and sits behind the cam timing belt sprocket. Again, this is a sensible preventative measure while having the timing belt off.

To install the new seal, it's important to protect it from the keyway of the camshaft snout when seating the seal. A simple piece of tape as a shoe horn covers any sharp edges, and some engine assembly grease on the bearing cap before reinstalling.

Here we finally have the new belt installed and routed around each pulley and roller, sprocket, and tensioner. While the cam and injection pump are locked with respect to crank and piston TDC, the sprockets are allowed to rotate into position to accommodate the new belt, while the crank is locked in place to maintain TDC.