Questions on 1999 502 MPI,both motors running at 170 and 180 degrees on water temp. Running 50 and 60 psi on oil pressure at wot. When down to idle oil pressure dropping to 20psi on one motor and little below 20psi on the other. It has Gaffrig Gauages with indicator lights. The red indicator light would come on when idleing on the motor that went little below 20 psi. Theys motors are surposed to be low hours on them. Oil has not been changed since may 2001, but the boat was not used last year. What do you guys think good to buy or stay away? Thanks

nitro/max,

Just because the gauge reads low doesn't necessarily mean that the actual oil pressure is low...it could be the gauge, the sender, or both. The first question I have is why hasn't the oil been changed since May 2001? Change the oil!!!! If the oil pressure is that low...I would expect a problem. I would have someone take a look at the motors anyway before you buy...compression test would be good, leakdown test would be better.

If you are looking at purchasing the boat.....have someone with a Merc scan tool (available at about $400+-) hook up to the ECM and look at the actual hours on the motor and cool things like hours ran at different RPMs.

Tell us more about the boat, motors, drives!!!???

20 lbs at idle is fine anyway

If my oil had been changed in May of 01, then it would have been changed again in June, July, August, and one more time for winterizing.

Buck

what weight oil are you using? you need a minium of 10 lbs for each 1000 rpm's so 50 lbs at 5000 rpm is ok and 20 at idle is ok also, if you switch to straight weight oil in a sae40 your pressure will pick up some, if your light is coming on hook up a mechanical oil pressure gauge to the engine and see what pressure it shows