Just changed the oil/filter and the oil pressure is higher than normal
 

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

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.:)

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

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.

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

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.

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

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
:)

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

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

on second thought, i am going to try to do that sender check next time i am out on the boat.


thanks again guys

james

JGB,
I'd be surprised if the factory changed the stock senders. I bet you'll see the same the same increase in pressure I saw if you change them. I changed mine because one of my senders started to go bad. I usually change my oil at 20 hours unless I see a 2-3 lbs. pressure drop which indicates time to change the oil early.

Dan

Formulafastech,
I agree about the electric gauges. Now you have me curious. When I change the other sender I'm going to put a mechanical gauge on to check. I know many Drag racers that preach high volume not high pressure. Thanks for the insight.
Dan

JGB,
Not sure if anyone had mentioned this to you yet, but when installing a new oil filter, dip your finger in some oil and apply it liberaly around the rubber seal of the new filter you're installing. Then all you need to do is HAND TIGHTEN the new filter on the threads. This way the next time you go to remove the filter it should be much easier to remove.

The pressure readings I quoted were with a high volume not a high pressure pump. I agree that too high of oil pressure is bad because it can push the oil too fast through the bearings and cause excess drag on the cam gear. But I still go by the 10/1000 rule of thumb. I have never had a bearing go out with this rule and I have run engines very hard in the past.

thanks kaama, i knew about that. i had watched my mechanic change the oil before so i picked that up from him. even though he lubed the seal i still had a tough time taking it off this time around. but i am pretty sure he used a filter wrench to tighten it. so i guess next time around it will be a pain again cause i used the filter wrench to tighten it also. i did lube the seals though.;)

next time i'll just hand tighten and hope it comes off easy for the following oil change.

thanks,

james:)

hi tinkerboater, i think the 10/1000 is valid. the 496 mags max out at 4800 rpm. so on the high end i should be looking at 48 psi. which makes my oil pressure fall righ tinto those parameters.

thanks again, i feel a sense of accomplishment after the fact. i have never changed the oil personally in a any machine with the exception of a riding lawn mower. At least i have my priorities straight with the interest i am showing in the maintenance of my boat. hopefully later on i will buy the service manual for the engines and try to tackle some other minor jobs as they arise.

currrently i still need to replace the fuel filters and noticed i have a small leak in the closed cooling system that needs to be addressed. i am hoping it is as simple as tightening a fitting. but i would need to tinker a bit to see exactly what the heck is going on with that.

are there any little secrets to getting leverage in hard to reach places in order to remove the fuel filters?

thanks again,

james

regarding oil filter tightness.

I would consider loosening them NOW and retighten to hand snug, then 1/4 turn. do this before the tightened ones' seals swell or you will be in the same boat (no pun intended) as this last time. You will probably still use the filter wrench next time t o remove , but they will come off much easier without blowing a forehead blood vessel like I about did this spring.:D

another trick told to me by Waterfoul, use one of those plastic grocery bags. open it up ontop of the exhaust, yet under your filter, then unscrew and drop the filter into the bag. "NO MESS, no burning oil smell first time out" much easier/cleaner than 10 oil soaked rags. and you don't even have to get your hands greasy;)

thanks rambunctious, i will try it next time out. i have spare oil filters so if i can get them off this time. i agree it would be well worth it.

thanks

james

Could be filter used. Many or most have a bypass valve in the filter or engine. If you use a cheap filter the bypass valve may have opened and allowing more oil through. Keep in mind if the bypass valve opens to soon, your not getting any filtration.
Recommend using a High Quality Oil filter such as the Baldwin B279

Make sure you didn't put to much oil in also.

Thread is 9 years old! :D