Pump Vibration

[hands87]

I have mounted my motor and connected the universal shaft. I have taken it out for a test launch and it idles fine but when I start to lay into the throttle it starts to vibrate from what seems to be the pump and the boat does not pick up speed. Could it be that the motor and the pump are not exactly inline and if so is there any way to adjust the shaft of the pump without making new motor mounts? The pump is a berkley. Any help would be great.

[Poida]

I could learn something from you Hands, Pump? is that some type of torque converter?

[hands87]

No torque converter my pump is direct drive form flywheel

[Poida]

Hands, nobody else seems to be helping you and I don't understand what you mean.

I have never fitted an engine and I drive in a boat but I am in engineering and fitted plenty outside of boats.

Sorry but I can't ubderstand where the pump comes into it. You have an engine to which a gearbox is attached, after which that shaft goes out of the back of the boat to the prop shaft. No pump.

Never the less a universal joint does not provide a smooth transmission, normally motors and gearboxes/pumps etc. are connected via a coupling with rubbers and even then alingnment is essential not only for smooth transmission but also for the life of the coupling rubbers.

As I said I don't understand where the pump comes into it unless it is hydraulic drive to the prop. Is the prop going around? Is the vibration cavitation in the pump drive ie no oil in the system or flow restriction.

Please provide more info or pics, or hopefully someone who knows more about what you have.

Poida

[Syed]

Checking the balance will be the first step for vibration at higher speeds, in my check-list.

[fatpat]

Berkeley has a troubleshooting page I'd check there first.

I'd also look at the 'universal shaft'. Does it have universal joint(s)? If so, what kind of shape are they in?

Next, how old is the pump? may be time for a rebuild.

pat

[Poida]

Ah, under powerboats somebody mentioned "Jetdrives," as this post has been submitted twice except where it may should be if "jetdrive" is correct and that is under "JETDRIVES!" which is a section under propulsion.

So if it is a jetdrive that explains why it has a pump instead of a gearbox.

I have absolutely no experience in jetdrives but engineering is the same if it is in a boat or operates an egg sorting machine.

I would assume that a jetdrive pump requires water to enter the inlet and push out of the outlet the same as any pump.

If I connected a pump and no water was coming out and there was a lot of vibration.

I would assume that the pump is running backwards, in which case the impellor on some pumps can screw themselves off, jamb against the casing and do lots of damage.

or the impellor is loose and the shaft is rotating inside impellor.

That's the only things that I can think of that would give you no propulsion.

If the impellor was rubbing against the casing it would create noise but you would still get propulsion of sorts.

Another thing that has just crossed my mind because you were not specific enough to encourage assistance if you have pulled the pump apart, you have put the impellor on back to front.

Hope this helps.

Poida

[AK-uniflite]

I have to assume that your intake grate is not partially plugged up? Even a few blades of grass will mess up you propulsion and cause cavitation.