Engine vibration

[89 Webb]

1989 20ft Webbcraft <br />5.0 Merc 200 HP<br />Stainless 3 blade 17P prop<br /><br />There is a vibration in the motor when I come out of the hole and if Im just at a low cruising speed (15-20mph) <br />I had the motor removed, repaired and then reinstalled. I only had been it the boat for 2 hours prior to the motor locking up. ( It only had 136 hrs on it & I bought the boat from the original owner) <br />There is no signs of damage to the prop. <br />The guy who did the R&R also replaced the seals in the outdrive. <br />Where could the problem lay? I have noticed in some other posts that there is a mention of proper alignment, would this fall into the same category? or should I be looking somewhere else?<br /><br />Thank You

 

[CCrew]

Re: Engine vibration

Sure the prop's not bent?

 

[89 Webb]

Re: Engine vibration

Good question however I changed the prop when I noticed all the vibration and it didnt change it. <br />Any more suggestions?

 

[LubeDude]

Re: Engine vibration

So am I understanding that this is a New engine!!<br /><br />If so, I would say that there may be an ignition issue! Maybe wires, Bad plug,(not unheard of even when new)!<br /><br />LubeDude

 

[Boomyal]

Re: Engine vibration

Run the motor in your driveway, using earmuffs of course, with the prop engaged. If you have a bent propeller shaft you may be able to see it wobble.

 

[89 Webb]

Re: Engine vibration

It's not a new motor. I had the mechanic pull the motor so we could see why it locked up and he found the timing chain or gear broke and waddded up causing the engine to seize up. We had to replace some bent valves and the crankshaft. He looked at the pistons, rods, etc.. all looked good. We installed new bearings, double roller timing set, gaskets, marine plugs and ran with it. <br />I also had him to replace the seals in the outdrive and install new impellars.<br /><br />The vibration is even there if I have the drive in neutral and ramp the motor while in the water, it seems from idle to about 3000 rpm the best I can tell. <br /><br />Would I have this kind of a vibration if the motor/drive was out of alingment?

 

[wheels4]

Re: Engine vibration

This might be to obvious but was the crank balanced? With the pistons,rods and flex plate?If not this could be your problem.

 

[89 Webb]

Re: Engine vibration

Thanks for the replies. <br />Actually that's another good reply! However, the company I bought the crank from ( it was brand new ) said I shouldn't need to balance it. <br />Maybe I shouldn't have listened!???

 

[89 Webb]

Re: Engine vibration

Any more suggestions?<br />How about if the motor/drive were out of alignment?

 

[Boatist]

Re: Engine vibration

89 Webb<br />Have you done a compression check. You could have a bent valve or one not sealing, even a bad lifter. That would normally be much more noticeable at low rpms. I had a bad motor mount that caused a vibtation one time but only under power as a certine RPM.<br /><br />I do belive a drive misalignment will also cause a vibration.<br />Good Luck and please tell up what you find.

 

[LubeDude]

Re: Engine vibration

Could even be a bad plug or a plug wire, certainly not unheard of! Pull the plugs and look at them, and then do you comp test!<br /><br />LubeDude

 

[K Hultgre]

Re: Engine vibration

Check the alignment, I would not go on blind faith that the motor is mounted exactly in the same place before the rebuild.<br />Depending on the RPM when the motor seized there were some forces to be reckoned with. Since the outdrive is constantly spinning with the engine running (gotta get water somehow), I would start by pulling the outdrive and use a blocking plate with adapter to get water into the engine while it is running and check for vibration. If nothing else it will eliminate the outdrive assy as the problem. After that you have the coupler and then the engine itself that could be causing the vibration. Not sure about the construction of the coupler but it could have suffered some hidden damage from a sudden stop. Have you checked the lift of each rocker arm (cam lobe) to help eliminate the possibility of a bent cam?<br />Good Luck, Let us know what you find.