I've recently bought a 2000E with one of these engines in that I'm working my way through. They have a couple of favourtite problems relating to the timing chain and the head gasket.

I had a water "sloshing" noise from my heater matrix, which turned out to be the head gasket. Pressure was escaping from the cylinders into the cooling system which then sent the air into the heater matrix causing the noise. Mind you - you can also get an airlock in the heater matrix which can be partially cured by swapping the pipes around on the water pump if this has not already been done.

I was really glad that I decide to change my head gasket. When I took the head off, the timing chain guides were all smashed, and one of the bolts had worked its way completely out. The bolt, and all the debris was sitting at the bottom of the timing case rattling around the crankshaft pulley. The torques bolt had a straight edge ground onto it through contact with the crank pulley. How it didn't get into the chain and snap it I'll never know - but the moral is not to assume your timing chain is OK on these engines without inspecting it...