I was wondering how likely is it for an oil pump to fail on a 1990 TT. Reason is my oil pressure gage is not working. Im going to have an external gauge put in. If the oil pump is failing what are the signs?

 

The usual culprit is a dead oil pressure switch / sending unit. If it's truly not getting oil pressure, the engine will make quite a racket.

 

oil pumps rarely fail. they deliver a fairly constant flow of oil to the system. They are gear pumps constantly lubricated by the fluid they deliver. as bearings wear your pressure falls even tho the pump is delivering the same flow. likely a sensor fairly as stated above.