Oil light on 91 jetta

[Doug Tatham]

I got an flashing oil light followed by a light with buzz after about 15 minutes idle. I just finished rebuilding the engine after it was driven without oil. I had put new sensors and a new oil pump in so I figured it was the oil sending unit behind the dash. I hooked up an oil pressure guage in place of the cyl head oil sensor and ran the car for 15 minutes and sure enough, the pressure was dropping to below the limit (.15 bar). I think the problem is with the cooling system and the oil is too hot. The temp guage on the dash reads just a little high, but I can't feel any coolant flow through the upper radiator hose when I squeeze it (engine running and hot - hose VERY hot to touch). I've never seen a water pump fail other than a wiped seal and bearing and can't imagine the impeller falling off. I didn't change the thermostat or touch the pump with the rebuild. Any clues why the coolant wouldn't be circulating?

[Doug Tatham]

For anyones information that runs into this problem. The impeller on the water pump had come loose. Problem solved. I bought the pump at a dealership, which surprises me since they are usually they are the most dependable source for parts.