Has this happened to you?

[86 catalina]

I just had my berkley jet rebuilt at a well known shop, and just took out my boat for the first time this season.It runs great from 700 rpm to 2200rpm at 2300rpm the boat shakes so bad it feels like its gonna fall apart ,then at 2400 rpm on the boat runs completly fine.Just to eliminate a few replies, right after i ran it for about a minute i shut it off and jumped in the water with my scuba mask and there was nothing in or around the pump at all,But that is just what it felt like.I had the shop completly rebuild my berkley pump ,on my receipt a few thing that i am unsure of are(wear ring/ss/straight-undersize),(overhaul&blueprint,stage1.5,alum,a-b-d-l)Also he machined my stock a impellor to an a/b impellor,he told me he just grinds the fins of the impellor down with a grinding tool is this a bad idea?I am thinking that since there is no way of load testing or running the pump at the shop "like you can with a jet ski in a test tank" that mabey this custom a/b impellor is the problem.Also should i have just went with an a or b impellor instead of the a/b combo.My boat is a 21 foot open bow boat with a mild built 496 engine in her..any help is appreciated.http://www.***boat.com/forums/attachment.php?attachmentid=14527&stc=1

[flat broke]

Have you called the shop that did the work? That would be the first place to start. Also, just because you can't see a rock in the impeller from under the boat, doesn't mean there isn't one in there.
Call the shop that did the work and see what they say. Outside of that, I'd say, check your driveline, flexplate to make sure the counterweight is still there, and check your oil for any traces of metal.
Chris

[TRG]

The imp. could also be outta balance!

[cave]

Did it vibrate before you took it to the shop?
Check your "U" joints or "H" bar. They may be done. Those are the parts between the engine and the pump.
Also the rock caught in the impellar. I had this happen and didnt feel the rock till I pulled the boat out of the water. It was wedged just behind the front edge of the impellar. I Felt it. I never saw it.

[Moneypitt]

Does it shake on the trailer?? ..........MP

[SmokinLowriderSS]

The folks I know who cut impellers turn them down on a lathe. I'd be afraid of a hand-grind being uneven and perhaps out of balance. Is weird that the shaking goes away above 2400RPM. Definitely check ALL hte moving parts for anyhting wrong/cracked/loose/missing weight/etc.

[sdba069]

When you say well known shop, do you know what they are well known for? I can't even imagine any shop grinding an impeller to size. Most of what was mentioned in the other replies are possibilities as to the cause of your vibration problem, but if somebody took a grinder to your impeller, I would go there first. Good luck and I certainly want to hear what you find out. The other thing I'd like to know is who did the work.

[86 catalina]

I will soon reply ..i want to talk to the shop first

[centerhill condor]

after my boat returned from the $4k jet rebuild (price includes travel back and forth and bronze impellor and intake replace) the boat shook so bad that it was affecting the gas gauges!
took it back and they put in new u joints and back in water. had a low frequency rattle/clank that would "go away" at about 12-1500 rpm.. as long as it "goes away" you're okay. so put about 5 hours on the boat and it has gotten better.
I was told the 3 way support was too straight and the U joints need some angle or they don't "do right".
My understanding is that with the new pump with new bearing the u joints have to generate their own play.
rub my neck and write a check and hope they'll go on their way. (waylon jennings)

[sdba069]

I've never been a player on that put a little angle on the driveshaft deal. I think that the straighter the shaft is, the less wear and tear there is on the u-joints. In a car sitting still, there is a little down angle on the pinion/driveshaft so that when it is under power and the and the rotation of the tires causes the pinion angle to move up, the driveshaft is straight. Since everything remains in line in a jet, makes since to me to keep the alignment as straight as possible.

[old rigger]

I've never been a player on that put a little angle on the driveshaft deal. I think that the straighter the shaft is, the less wear and tear there is on the u-joints....
You're 100% correct. Anything that's set up where the H bar is not dead on straight, is wrong. I've never, ever seen one fail when set up the correct way. :)

[NautiTwins]

Dont know if this has been said. But mine did that when the U_joint was starting to go out.

[sdba069]

Certainly, one of the things that need to be checked, but I still haven't gotten over the grinder deal. I hope the boat owner simply misunderstood what the pump guy told him. I can't help but think about all the toys I could have bought with that $25,000 I invested in a lathe and Bridgeport, instead of a grinder.

[Bense468]

I was too lazy to read anyone elses post so maybe people said this, but I had that problem one time a long time ago on my boat, and I thought it was the pump. turned out to be the Driveline and flexplate coming loose. I didn't put it together, somebody else did at a well known shop as well, but I fixed it with some locktight and I was back in Biz. Might want to check u-joints. Next step thrust bearing etc.

[86 catalina]

I figure i will check all of these parts before i take the boat into the shop.Flexplate,universal joints,etc..The only problem is that i didnt change the driveline patrs at all ,they are the same ,but i did just toss in a new 496 .i will keep you guys posted.thanks.What do you guys think about a/b combo blade?Should i go with a a or b?Also when i talked to the shop he asked if the timing was out,could that be a problem?I might have been off a degree or two.

[86 catalina]

Does it shake on the trailer?? ..........MP Should i get it up to the rpm that it was vibrating at?2300

[Bense468]

This is what I experienced about 5 years ago in my old boat. I was cruising up the parker strip and it was running great, then all of a sudden It started shaking so violently that I thought the boat was going to come apart, then I slowed down and it went away. When I put it on the trailer after checking everything out, it would rpm fine on the trailer. It needed the load to vibrate, so I dropped it back in the water, and same thing. So right back on the trailer it went and I tore it down. My flywheel bolts were backing out, and so were driveline bolts. I locktighted them and locked them back down, and it ran great the rest of the trip. Thats what I would check first (along with U-joints)
Timing is not going to cause that, but a thrust bearing might. As far as what impellar you should run. I would suggest an "A" if not an "AA" for lower plane speed, and fuel effiency. Might be 2 mph slower on top end, but its going to come out of the hole better for a 21 foot boat. Thats my opinion though.

[sdpm]

I figure i will check all of these parts before i take the boat into the shop.Flexplate,universal joints,etc..The only problem is that i didnt change the driveline patrs at all ,they are the same ,but i did just toss in a new 496 .i will keep you guys posted.thanks.What do you guys think about a/b combo blade?Should i go with a a or b?Also when i talked to the shop he asked if the timing was out,could that be a problem?I might have been off a degree or two.
What engine did you change out? If you used the same flex plate or flywheel from an externally balanced engine (454 BBC) and went to a newer 496 or built up a 496 the balance will not be the same!

[86 catalina]

i bought the motor from a guy that did not know anything about it and didnt know much about motors either.When i bought the motor from him he said it was ready to go in a boat<thats what the person told him that he bought it from apparently> thank god i didnt trust him.So i tore the complete motor down and had to rebuild the whole thing.I took it to the machine shop and they said it was a 13.5 to 1, 950 hp drag car motor.I had it detuned to a 10 to1 600 hp engine.Srp pistions,scat crank rods,world product heads,full roller valve train with comp cams components,barry grant carb,edelebrock 7000 rpm mani,etc.So to make a long story short the motor was not completly assembled.But it did come with what i was told to be the 496 flex plate,but i am not sure.Could this be the culprate the my vibration.Let me get a few pics up so you all can see what we are dealing with.http://www.***boat.com/forums/attachment.php?attachmentid=14562&stc=1 http://www.***boat.com/forums/attachment.php?attachmentid=14563&stc=1 http://www.***boat.com/forums/attachment.php?attachmentid=14564&stc=1 http://www.***boat.com/forums/attachment.php?attachmentid=14565&stc=1 http://www.***boat.com/forums/attachment.php?attachmentid=14566&stc=1

[obnoxious001]

i bought the motor from a guy that did not know anything about it and didnt know much about motors either.When i bought the motor from him he said it was ready to go in a boat<thats what the person told him that he bought it from apparently> thank god i didnt trust him.So i tore the complete motor down and had to rebuild the whole thing.I took it to the machine shop and they said it was a 13.5 to 1, 950 hp drag car motor.I had it detuned to a 10 to1 600 hp engine.Srp pistions,scat crank rods,world product heads,full roller valve train with comp cams components,barry grant carb,edelebrock 7000 rpm mani,etc.So to make a long story short the motor was not completly assembled.But it did come with what i was told to be the 496 flex plate,but i am not sure.Could this be the culprate the my vibration.Let me get a few pics up so you all can see what we are dealing with.
If the "496 flex plate" was not balanced to your new rotating assembly, that could very well be the problem. When you state that you had it "detuned to a 10 to 1 engine", did you replace pistons and have the engine rebalanced? A 496 could be either internally or externally balanced, and would require the correct flexplate, either with or without a counterweight. It should have gone to the balance shop along with the crank, rods, pistons and harmonic balancer. Another possibility is that you can put a flexplate onto the engine (crankshaft) backwards, which would definately cause an out of balance situation with an externally balanced engine.

[Pops@Aggressor]

[QUOTE=
I was told the 3 way support was too straight and the U joints need some angle or they don't "do right".
My understanding is that with the new pump with new bearing the u joints have to generate their own play.
QUOTE]
True: The Line should have 2 Deg to 4 Deg., Max. This puts a load on the bearings allowing them to work. On a straight line up, clatter will occure and the bearings are not getting worked as should.- Bal. on Impeller should be re-checked after cutting and may have been..

[sdba069]

You can't sell me on that misalignment theory.

[86 catalina]

A 496 could be either internally or externally balanced, and would require the correct flexplate, either with or without a counterweight. My 496 is a gen 4 motor two peice rear main seal.How can i tell if the 496 is internally or externally balanced.Also is thier a chance it could be the harmonic balancer.I got two with the motor and reinstalled the one that apparently came with the crank.

[Moneypitt]

If the flexplate/balancer were the wrong one(s) it would shake at an idle, at least some. You said it started further up in the rpm range.. BTW, have you established if it shakes on the trailer yet???..........Ray

[86 catalina]

It dosent have the shake at the same rpm on the trailer as it does on the water.Because the motor is built ,it lightly shakes all the time but not like when its under a load in the water.When in the water it shakes so bad uder a load you can see the whole dash shake alot (only at the certian rpm 2400).When i rev the boat up to the same rpm on the trailer its nothing like the same shake i notice in water.Should a flexplate for a 496 have counter weights on it?Thanks for all you help ray.