V8 pro xs shaking

[CaymasMan250]

While hitting waves/ rough water mines looks like it is about to fall off. shakes bad, I suspect the soft motor mounts are to blame.

Mine is very noticeable in a decent chop as well.

[21xTriton05]

Mine is very noticeable in a decent chop as well.

The mounts are doing their job & not transfering the energy to the boat. They are softer than the 2s pro xs engines for sure

[tuffnugly81]

Mine shakes pretty well also. Just got the 10 hrs break in done and was surprised when I looked back there going down the lake on memorial weekend

[toledo freak]

Exactly! For those that say theirs don't shake or not more than older opti pro xs? Obviously haven't turned around and watched motor in any kind of chop! " it's freaky", I know it's normal now! Not saying I'm crazy about it, time will tell if they engineered these mounts tough enough because they sure do work overtime! And if you think these mounts are soft? Go drive a 115proxs 4s in a chop

[EuropeanAM]

Toledo... thought you have a 250 (that's what your original post was, anyway).

Have you had someone ride with you so you could video the engine and water behind the boat while this is occurring? Would be interesting to see it.

[low slung cruiser]

i just wanted to go back and bring this back up...
my 2019 v8 does same exact thing...
while cruising and hitting decent size chop, this motor does seem to have ALOT more up and down chop than any of my 3 previous Pro XS 2s models...

[EuropeanAM]

Definitely far more absorbent mount system used on these Fourstrokes. That is an integral part of the sound-decibel reduction measures.

[low slung cruiser]

makes sense....does the R motors use the same absorbent system?

[EuropeanAM]

Comparing the 250 ProXS 20" Mechanical, to the 250R 20" SM and the 300R 20" SM (there are a number of other models that vary):

Upper mount is different on the "R" models, lower is the same (except for the HD Swivel Bracket models, which are totally different).

[12many]

ya i looked at mine other day . actually checked bolts after run. motor jumps a lot when i really let er eat ..
scary to stare at. but smooth at helm. im sure it some sort of optical illusion??

[fishnfireman]

makes sense....does the R motors use the same absorbent system?

My 250 R seems solid although it has some vibration at lower RPMS that seems prop related

[southern_gt]

My 250 R seems solid although it has some vibration at lower RPMS that seems prop related

I have recently noticed some vibration at low RPM. All though mine is not the R engine.. I have looked at every thing I can I can’t find anything that stands out as wrong. You said “prop related” what could that be? I have some chatter or vibration but I don’t feel any slack in the LU or anything noticeable. Could it be LU related or going out?

[fishnfireman]

The first props I ran were 4 blade promax... both had a noticeable vibration at lower rpms but seemed to go away at higher rpms.
When I put on the 5 blade max5 prop it was a lot better. After getting the new style hub its not noticeable with the 5 blade. But haven't tried it with a 4 yet. Others have talked on different forums of a low rpm vibration and how it's less with more blades.

[EuropeanAM]

I have recently noticed some vibration at low RPM. All though mine is not the R engine.. I have looked at every thing I can I can’t find anything that stands out as wrong. You said “prop related” what could that be? I have some chatter or vibration but I don’t feel any slack in the LU or anything noticeable. Could it be LU related or going out?

Let's be careful not to confuse or hi-jack the thread topic, as seemingly small deviations can rapidly turn into discussions of something completely different.

Some of the low-RPM vibration being noted on the "R" models is due to the stiffer (upper) mounts, which allow more vibration to transfer from the midsection through the transom brackets, and on to the boat.

[framer]

motor bounces around a lot,but still stays connected to the water.kinda crazy to watch

[fuelleak]

Ok people I've put my hands on several more 4s and dug around, like I suspected it appears normal and appears the 4s has rubber mounts vs the opti pro xs having solid mounts! Therefore the noticeable difference in motor movement! And to those saying your 4s doesn't move anymore than your older opti pxs?you obviously haven't turned around and watched this 4s as you are running down lake in any kinda chop! It's pretty 😳Eye opening! Or just have two side by side on trailer and do a repetitive push test on cavitation plate, " night & day " fellas! With that said all is good now that I know it's not just mine, 👍

I have been saying it all along. In rough water the motor shakes so hard it shakes the boat. My 250 does it and my partners 200 does it.

[Elwood]

My SHO used to do the same thing and it was the play in the Atlas Jackplate in combination with the soft motor mounts. That is one of the reasons that I went with a Bobs backplate on my current boat. I have the 300R and the it does not have the bobblehead effect in a chop that my last boat had. Actually it has hardly any play and is very solid back there. And yes I look because my last motor did it so bad that it would shack the boat pretty bad. Check for play in your jack plate also.

[low slung cruiser]

its not left and right shaking...its forwards and backwards... and its physically impossible to manipulate it by hand on the trailer...

[low slung cruiser]

Yep that’s it...
mine does same and maybe worse

[EuropeanAM]

When did Mercury make the change to the softer mounts? My buddy has a 2016 115 4s on his boat and it doesn't have nearly the amount of movement that my 2020 does.

That would require the serial numbers of both engines to compare.

While much of this discussion has become general- the lions share has also interjected engines that are a completely different series from the Original Poster's (V8 ProXS) engine. We do need to keep the discussion more directly focused on the ORIGINAL-POSTER'S engine/question so that it doesn't become necessary to clean the thread.

Thanks!