502 oil pressure question yet again
 

i have a pair of year 2000 502 mag mpis 415 hp ,problem is at start up oil pressure on gauge reads over 40 the second it is reved at all it drops right of the gauge ran it tonight only up to 3000 rpm and the gauge went right of the scale !mechanic says he has changed the sender but he reckons its more major than that now , or has he ?????? please help also getting intermitent alarm bleep hit the trim button and it goes away sometimes !

The first thing you need to do, is hook up a mechanical guage to verify that there is no problem with your dashboard electric guage. If in fact the oil pressure is dropping as your dash guage indicates, I would suspect that the pick up has come off the pump.

vinny thanks so much ,where do ifind the pick up on the pump,
the gauge says over 40 on idle , if you rev it it very quicly the gauge flickers fast , then onnce you running it drops of the scale completely , is the pump an easy fix ?

Electrcal .... as stated get a 20.00 mech oil gauge from Auto zone ....that will tell you alot ....I doubt its the pickup ....

ok i will try to hook up a mechanical pump, rang my guy who looks after it reckons do the gauge thing any way first ,but if not that its engine out check the pump and do the bottom shells and see !!!!!!!!!!!!!!!!!!! sounds expensive on an engine that has done 335 hours what do you reckon

Like the others said, test it with a mechanical gauge. If it is good it sounds like you have a ground problem. Usually when gauges flicker or change when switches are activated it is usually a bad ground.

thanks bd hope to test it tommorow , really hope it is the gauge it seems to flick back really hard to bellow zero once you put the revs on !

If the pump loses a pickup, you'll most likely get zero oil pressure.

I certainly would not let him pull the engine without putting a mechanical guage on it first.

I agree that its probably an electrical short somewhere and the pressure is most likely fine.

do the mechanical gauge, if it does the same, try adding 3 extra qts of oil see if changes, if it helps, good bet the pick up has come off..time for the engine to come out..Rob

ok hi guys and thanks all for your help , ordered a mechanical gauge today hope to get it by tommorow, in the meantime i swapped the gauges around no change found there , then swapped the senders around and yes he had renewed the questionable one !!!!!!! no change there , rrrrrrrrrrrrrrrr so now im just hoping its a grounded wire, tommorow i will know once i read the mech gauge, i will give an update , it is in baja 342 1they are known for wire probs also theres a bleeper going of i did add a bit more oil and it did put up the pressure a bit but it wasnt under load just on the hose. i really hope it doesnt have to come out , but i beat it will then i guess its oil pump and bottom shells ???

By saying " Bottom shells" , I assume you mean replacing the crank bearings? If the bearings are damaged or worn out and in need of replacement, at the very least, you need to tear that engine down, pull the crank, polish or cut it, check the oil clearances. Then install the appropriate sized bearings. Thats assuming the rest of the engine is in good condition or isnt full of metal from damaged bearings

the pickup if not altered is spot welded into the pump by merc

ok an update put the mechanical gauge on today !!!!!!!!!!!
yipeeeeeeeeeeeee it runs good 40 at iddle then rev up and its upto just under 60 so that is good news no work needed on the engine , so thank fully its a wiring problem where do i start as gauge is ok so is sender !also there is an intermitent bleep alarm going of! so at the mo im happy !!!!!!!!!!!!!!