Optimal oil pump o ring replacement

[samsmallie]

I’ve read a lot post about changing the o ring on a optimal oil pump but can’t find a video of somebody actually doing it and I’m not gonna spend 400 for oil pump when I don’t need one, any help appreciated

[JOE54]

lot a info in 3.0L section on this

[ride.race.live]

As Joe said most of the info on these oil pumps is in the 3.0L section.
I've done my share of research on this... The O ring size I came across that others have used was Size 128 Material 75 Shore A Viton

Im with you on not willingly throwing $700 (cost for me for new pump) due to a poorly fitting O-ring from merc. You'l see pretty quickly what i mean once you open the pump, it sits loosely in the machined seat. In my opinion this O ring should be a tight fit to prevent any kind of "flex" or movement as the pump cycles. heck ive seen better fitted O rings in damn Chinese knock of motors then these oil pumps.. its damn sad... (end of rant lol)

I will advise that you look over the pump internals closely to ensure everything else looks ok. Ive read on here that a few guys ended up have a hairline crack in the "piston" portion of the pump (bare with me as I dont know the correct term for it) and still ended up with leaking oil pump.

The break down of the pump is pretty darn basic and really no way of installing back together wrong, I took an added precaution and marked the outside of the housings so I could line it back up to the way it originally was.

Once you disconnect the oil lines (make sure you take note which oil lines go where on the pump) and have the pump in hand. All you got holding it together is 3 bolts.

Once you remove the 3 bolts this is what will come off 1st


the next part you will see which may need to be wiggle a hair to pop out is the "piston" That shaft portion is where ive read some guys reported hair line cracks. Once you remove this piece you will see the O-ring that is the cause of the leak (in most cases)



From there all thats left is the plunger and a spring. once you lift the plunger out youl see the spring sitting in the middle. You cant mess up re installing the plunger as notched and will only go in 1 way.

[samsmallie]

Man thanks a ton for the info, this helped a bunch, it really is sad what our quality has become in this part of the world, we would have less failures if things were done better but then there wouldn’t be any turn around so greed drives everything these days

[ride.race.live]

no prob... id still recommend doing a little bit of searching on here, a lot of good reading about it as well as opinions.....

Im still on the fence on whether I want to just replace the o ring in mine or not truthfully but that is mainly due to the fact my motor has around 500+ hours and is 14 years old.... more so knowing its 14 years old as the hours isnt too bad... on that note though.. i bought the boat this past summer so I have no idea on how long its been leaking.. from the mess I have in the cowlings and build up of grime... i'd say its been seeping for quite some time.

But yea... its pretty sad... half assed machine oil pump with an incorrect o ring size.. or o ring hardness / memory as it just seems to loose its shape overtime then start leaking...

[EuropeanAM]

Sam- you never said what engine you have.

This idea of "oil pump repairs" or o-ring replacement is not something I recommend. Simply not worth the risks for my engine(s), or my customer's.

[samsmallie]

2014 250 pro xs, changed o ring little while ago, gonna take it to marine repair shop tommoro and let him put computor on it and do the purge, ive heard of people doing it themselves but im skeered.

[ride.race.live]

If your stressed about doing the O ring "fix" i'd just get a new pump... nothing worse then being paranoid about something every time your out. I've been in that position before and its not fun...

As Don said... its not something he personally recommends and hes not the only one.

I do 100% agree on getting the oil pump primed by the merc diagnostic tool. (and not the reset break in mode method)

All in all... Don is the one with reputable experience....

I just dont personally see why / how im risking anything swapping out an O ring considering you really cant re assemble the pump incorrectly... worse comes to worse it still leaks in which case go new at that point.... (odds are youl spot a leak during the oil pump prime if it does....

[Ranger RT]

Changed my o ring awhile back... still dry

[aarchdale]

Why spend that kind of money, when an O ring can fix it. If i was a customer and was told i had to buy a whole new pump because an O ring was bad i would be moving down the road to the next dealer

[ride.race.live]

I can see why a certified mech would not stand behind this type of fix.... it's not supported by merc.

Takes 1 person to say "well this expert tech told me just to put a new oring" pop... and now hes in trouble...

If I'm going to a dealership for a fix... I'd want it to be by the book. Their hourly rate is expensive enough I wouldn't want a backyard fix

But it does. Make it sound pretty bad when you have to throw out a 700$ cad part due to a o ring leaking when its accessible by removing 3 bolts

[fly by night]

I concur with Don and ride.race.live. That sounds like a tedious process and very risky to say the least, especially considering the cost of boat motors plus you have to deal with the oil pump prime process. I personally wouldn't risk it but good luck to you if you try it. I hope it is successful for you, to each his own.

[aarchdale]

I guess i would feel different if i had a newer rig. Mine is getting old and has served it purpose. Just seems like you her of so many leaking, that merc could come up with a cheaper solution

[ride.race.live]

im with you on if it was a newer rig... but then again... i'd be pretty pissed off having a newer motor and having a BS leak like that...

and 100% on a solution but at this point its safe to say its not going to happen.

[SilverFox579]

The Optimax was discontinued just prior to the new 4-stroke release last year. Highly doubt Mercury would invest anything toward discontinued product.

[mattyin90]

I’m currently trying to diagnose a leaking pump. Do you think a small crack on the brass shaft plunger is to be a concern? I’m dripping a small amount of oil out of that crack and am unsure if replacing the o ring seal will stop the leak or not. I inspected my o ring and it isn’t visually damaged but feels a little hard and it might not be providing enough of a seal.

[lpugh]

I’m currently trying to diagnose a leaking pump. Do you think a small crack on the brass shaft plunger is to be a concern? I’m dripping a small amount of oil out of that crack and am unsure if replacing the o ring seal will stop the leak or not. I inspected my o ring and it isn’t visually damaged but feels a little hard and it might not be providing enough of a seal.

Replace the pump, you can not stop the leak with that crack as the cover is vented and must stay vented for the pump to function. Many of these leaks are because of that crack and many are simply the three screws are loose

Keep in mind a Dealer would lose in court by replacing that o-ring should the pump fail for any reason as it is not an approved repair, you can count on that, The would be held responsible for consequential damages as well, Not at all worth the risk involved

[mattyin90]

Replace the pump, you can not stop the leak with that crack as the cover is vented and must stay vented for the pump to function. Many of these leaks are because of that crack and many are simply the three screws are loose

Thanks for the confirmation. I was reading online that the crack isn’t the problem and that the o ring just needed to be replaced. I will order a new one.