JGB

what does this mean. i have the 496 mags and the oil pressure usually is is a hair or two above 40. after changing the oil the oil pressure is right where it should be at idle but above 2600 rpms is jumps up to a bit over 50 revving at the dock. is this normal or should i be troubleshooting?

any help? please!


thanks,

james

excaleagle42

james
did you use the exact same viscosity and brand of oil, same filter, and same engine temperature when taking readings? even if everthing was the same i wouldn't worry much because the new oil has less contaminents and your pressure went up and not down.

JGB

thanks for the response, excaleagle. i REALLY appreciate it!


i am kind of worried cause i have twins and the other engine is holding pretty close to the 40-43 range at all rpm ranges. i changed the oil exactly the same on both, the correct filters and the correct oil weight, and proper readings at the same temps.


but i don't know what could cause the spike in oil pressure above 3000 rpm. ????????????????? anyone have any ideas. i am a worry wort and this is making me crazy.


is oil pressure above 50 a bad thing? i know low oil pressure is bad but how about high oil pressure?


thanks again excaleagle!

can anyone else lend some help to this newbie?

thanks in advance,

james

Tinkerer

Bottom line is you need 10 psi for every 1000 rpm the motor is turning at- at the time. I would expect the oil pressure to go up a little with new oil.

JGB

thanks for chiming in tinkerboater. i appreciate.

another thing, why the heck are those filters such a pain to get off? i went through 3 filter wrenches trying to get those two filters off the twins. i wanted to change the fuel/water seperators also today but their location on twin 496 mags has to be the worst. lower right hand side of the engine facing the stern of the boat. their was no way i was tackling that after working off the stubborn oil filters. i also punched holes in the top of the oil filter (its one of those that hangs upside down, not the normal way, i guess it is the new way merc does things) to see if that would help but to no avail. i think it actually made it worse cause when you put some pressure on with the wrench it seemed easier to crush the casing of the filter which made it more difficult to properly grip the filter.



it was a long day to say the least. i guess that adds to my frustration of not knowing why one engine's oil pressure spikes over 3000 rpm??? and the other maintains that 41-44 like a rock through all prm ranges.

thanks again

james

Tinkerer

At cold start up I am at 70 psi after engines warm up at idle I am at 40-50 psi. At WOT it is 70 psi-after sustained WOT going back to idle the oil pressure will drop to 20-25 psi but as oil cools it will come back up to 40 psi. As long as your pressures are similar to these I would not worry. The engine I am nervous about is the other one. Does the pressure go up to 60 - 70 psi when reved up above 3000 rpm? Also oil the gasket on the new filter and only put it on hand tight -SNUG- no wrench- I never have had a filter leak doing it this way and they come right off with a wrench.

PM --me with your responce so that I don't miss it. 40-45 psi on an engine turning 5000 rpm is bad and you have something wrong.

JGB

thank guys i appreciate your help and advice. i will be taking her out for a spin today and will let you know how it goes.


thanks again

james

JGB

just got back from the boat ride and everything seemed to go well. both oil pressure readings were virtually identical. so i'll take that as a good sign that the oil change went well.

thanks for everybody's input. since i am one of those worriers i sincerely appreciate you r responses. you helped me lower my blodd pressure a great deal over the past couple days.

thanks again

james

candyman35

Are you running Gaffrig gauges? The stock senders from Merc don't match up with the Gaffrig gauges. My boat went from 42 lbs. to 60 lbs. by changing the senders. Check the connections to the gauges while the engine is running. Try putting sideways pressure on the connections and see if your readings fluctuate. It could be a loose ground. As long as the pressure is higher and not lower you should be fine.
Dan

JGB

thanks candyman, i do have gaffrigs but don't think it is an issue on my boat. meaning it was probably already taken care of at the factory.


formula fastech, at WOT they were probably 43-45 psi. that's a little higher than where i was at before the oil change. so i assume the new oil bumped up the oil pressure a bit as it should.


thanks again guys

james