Oil Pressure

[drrhein]

http://www.dotphoto.com/go.asp?l=drr...4362631&Pres=Y

My 1985 500SL euro has recently developed an oil pressure problem when hot. The pressure reads zero at idle. However if you look at the oil spraying on the camshaft (looking through oil filler hole) there is no difference between when cold and reading 3 bar and reading zero. Another thread suggested I look at the pressure sender, but I can't find it anywhere. The pressure relief valve, suggested by another, is on the oil pump and the pan has to come off for access. (engine has to be removed to get pan off) Anybody had this problem????

Dennis