What would cause such a vibration in the hull?

[Hollis]

Cruising along at about 35 mph or more I can feel a small vibration around the hull. Any ideas would be greatly appreciated before something breaks or falls off.

[Chestah Cheetah]

Trade that Seaswirl in for a Bayliner - problem solved! http://www.plauder-smilies.de/happy/biggrina.gif
What is the water condition like when this occurs? Your RPM's? Can you "power out" of it and past it? Does anything cause it to change?

[572Daytona]

Check your U-joints on the drive line, when mine failed I had a lot of vibration

[HBjet]

Hmm, check the driveline and make sure everything is tight. I would also remove your hand hole cover to see if you have anything tangled on the pump shaft or impeller. If you find nothing, disconnect the driveline, and trun the pump by hand. It should be smooth. IF everything is ok there, start your motor with the pump disconnected and see if it's a motor problem. Good Luck!
HBjet

[Chestah Cheetah]

Just out of curiosity and for education purposes, if the driveline is problem, wouldn't the vibration occur at any speed/RPM?

[HBjet]

Originally posted by Chestah Cheetah:
Just out of curiosity and for education purposes, if the driveline is problem, wouldn't the vibration occur at any speed/RPM?
If your driveline is just a little loose, at idle, You probably won't notice it. When you start turning it at higher RPM's, very small issues become bigger ones. Since it was a slight vibration, you just my need to tighten a bolt here or there. It also could be something small caught up in the impeller, but you would usually feel that when accelerating out of the hole.
HBjet

[spectras only]

Hollis,you could be missing a chunk of the trailing edge of one of the blades on your impeller.Make sure you disconnect the battery ,before you reach inside the impeller!

[BBB]

I have a question along the same lines except my vibration happens at idle and is intermitent. It sounds like a a deep rumble and I was told by the builder that it is inherent with the stainless A&B impeller that was installed. Can anybody confirm this for me?

[HBjet]

Originally posted by BBB:
I have a question along the same lines except my vibration happens at idle and is intermitent. It sounds like a a deep rumble and I was told by the builder that it is inherent with the stainless A&B impeller that was installed. Can anybody confirm this for me?
RR has the same problem at idle, but the vibration is from the blower motor idling.
As for your problem, I have never heard that before with a stainless. Sorry.
HBjet

[spectras only]

BBB, if the impeller balanced ,it shouldn't vibrate at any rpm,however if it's slightly out of balance ,you may experience some vibration at certain rpm's.Altering your rpm's should cancel out this condition,however it would be advisable to pull the impeller and have it checked by your local jet guru.

[Hollis]

I just greased the ujoints, All the fittings I could see. The Impeller looks good and no weeds or play in the driveshaft..I'll double check the rpm's this weekend. Thanks
[This message has been edited by Hollis (edited April 23, 2002).]

[Kwicherbichen]

You might also get some mild vibration from a pump bearing going bad. Mine is kinda doing that.

[Hollis]

Kwicherbichen, Judging by the diagram I'll have to pull the pump rite from the stern to replace the bearing...is this true?

[Kwicherbichen]

Hollis,
Truth be told, I don't really know anything about fixing your problem but.....I did stay at a Holiday Inn last night. J/K
Really though, do a very close examination of the impeller. If it's stainless there shouldn't be any chunks missing but if it's seriously damaged (ask Jim Lee or 77Charger) it could cause an out of balance vibration. I have never heard about the stainless steel vibration either.
Next, spin the pump without the drive shaft hooked up. Perhaps the shaft is not straight? That could cause a vibration.
On my pump I recently picked up a low rpm vibration in the water and a squeel while it's out of the water. It was loosely diagnosed as a bearing going out. The squeel started shortly after the vibration so I'm just putting 2 and 2 together.
I hope that helps. It may be more cost effective to give MPD or Tom Papp a call and see if they can help you diagnose over the phone.
Brian
BTW, you never really told us much about your boat. Did the vibration start after having the SS impeller installed, a run through rocks, a motor mod, and so on.
[This message has been edited by Kwicherbichen (edited April 24, 2002).]

[Licketty Split]

I had a winning noise accupanied by a vibration that you discribe, it was my trust bearing http://free.***boat.net/ubb/frown.gif I knew that it was going but I gambled on it to get me through the summer. When it finnaly self distructed my RPM's went from 3500 to 2000 instantly as the the impeller when into the suction housing. I should not have gambled on it http://free.***boat.net/ubb/smile.gif

[RP]

Hollis,
I had a vibration that you could feel in the hull which turned out to be the bearing in the pump shaft. After the vibration continued for awhile it started to make a whining noise. I was told that if I would not have replaced the bearing it could have done some serious damage to both the motor and pump. I would definetly have it looked at.

[spectras only]

Hollis, first thing to check is the thrust bearing,if it gets hot [the housing should only be warm to touch ,not hot],that means you're ready for a new one.Second ,you shouldn't be able to move the pumpshaft up/down by grabbing it through the cleanup hole.To replace the tailbearings ,you have to remove the bowl/transom adapter.I've seen people discard the "O" ring for the adapter to seal, and use silicon instead for easy bowl removal for the future.I always use the "O"ring ,and if the adapter is too tough to remove first,then I undo the adapter fasteners and the 8 bolts that hold the bowl to the intake and pull the hole assembly together.You need a proper size mandrell to push the tail bearings out.Some people wack them out with a handmade driver and a 5 pound hammer,but I don't recommend that.[you could crack the bowl that way].You can have a machine shop to push it out with ahydraulic press.If you have a buddy with a shop it's no big deal,and he could make a mandrell for you as well.

[Bense468]

Check your drive line, pressure plate or flywheel to see if it is coming apart. Also check to see that you did not break the keyway on the balencer or dampner and make sure it is tight. I have seen this happen before and it will send vibrations also. Good luck

[Hollis]

I bought this 1979 21' Checkmate 3rd hand so any thing could be wrong with it, and up here in Maine nobody works on them. Thank god I have you guys and this forum.

[77charger]

i had an all around vibration when my u joints went out. was before i damaged my impeller (same trip)only got worse when the impeller was trashed(hit a sand bar)