welcome back i havn't seen you for a couple of days. i took the top hose off of the engine and filled through the rad. then took off the other end from the rad. and filled to the block. also is the reservoir vented should it be spitting hot water from the res. should i plug the hole?? what are the chances of getting a bad thermal switch and thermostat. should i leave the parts stores alone and just go to the VW dealer and pay the price for oem parts??
ah, that might be your problem. If you filled through the rad first you would have forced air down into the water pump, where it could not escape because the thermostat is closed. Try filling it by pouring through the top hose into the engine until the coolant pours out of the hose, then reconnecting the hose to the rad.
Re: chances of getting a bad thermostat: pretty good. Happened to me. Almost warped my cylinder head.
Re: should it be spitting hot water from the reservoir: in my opinion no. My vw diesels have never done that. When they overheated, the coolant came out of the cap. But maybe if the cap is not working then the tank will have another relief valve to prevent it from exploding. Probably does.
You said you replaced the water pump right? Because that can cause very quick overheating if it is not functioning properly. The other cause could be a blown head gasket leaking compression into the cooling system. That sometimes happens on these turbo diesels because of the amount of pressure in the cylinders. It is already a very high compression engine, and then you add a turbo....very very high compression...sometimes I wonder about VW engineers. Anyway, good luck with it.
Chris
ps, in very rare cases, and usually only on the old rabbit 1.5 NA diesels, the engine blocks developed cracked water jackets allowing the coolant and the oil to mix. This could sometimes result in the cooling system becoming pressurized since diesel engines operate at positive crankcase pressure (ie, no engine vacuum). But if this was the case with your car, you would see oil in the coolant. Since you don't, the worst it could be would be the head gasket, unless the cylinder head is cracked and compression is leaking in that way, but you will see that when you take the head off (if you end up having to do that)