DAR400

Its a 96 300 Tdi

300tdi 90 I recently had an overheating issue caused by what I thought was a slit pipe, I now think that the split pipe was caused by the overheating issue itself. The pipe in question is the one to the heater rail across the engine from the radiator hose brach. I think due to the extra heat this has expanded just enough for the water pump pulley to chaff through it causing the leak. I have changed the hoses (all of them ) flushed engine with engine plug removed and flushed the radiator, refilled it as per the book topping and capping off the rad then the thermostat housing from the expansion tank. then added 1 ltr extra as advised in work shop manual (took 11 lts in total), ran for 5 mins. During this initial 5 min running the cooling system seems to over pressurise and therefore expel bountiful amounts of coolant out of the expansion bottle pressure cap. When I then inspect the thermostat housing its dry ! I tried again again and also checked the thermostat itself which is fine, same result. I can confirm that the water pump impeller is turning when I move the pulley wheel, bubble catcher is clear and expansion tank is fine, am a bit baffled about what could be wrong, or what I'm doing wrong. thanks DAR

I have gone through the process as described in this great link and used a 5 Amp fuse as the test jumper, this blew when I tried each side on the indicators , what should I check next, cheers