Vibration from I/O (not sure from where)

[Wanshot]

Hi all, OK after replacing: I/O Alfa one (all brand new including u-joints), lower shift cable, all the bellows, G-bearing. Greasing all zerk fittings on gimbal housing (with marine grade) and a rough shift cable adjustment, I took her out for a test run. Results: (Note, I am following manufactures break-in procedure to the letter) I found fwd gear nice and quite going into and out of gear. At the dock, reverse the same. After running awhile and testing reverse I found it hard to get out of reverse and not at the right spot in shifter. ( ok just some adjustments to do nuff said). However running her at 3500 rpm and trimmed all the way down, I get a vibration kind of like my truck on a dirt road, (subtle but absolutely there). Now while running the engine in neutral I brought the trim up for a look and noticed that I forgot to put the trim tab bolt in (never had a trim tab, looks as thou would hit prop. Only had the allen bolt installed) , this allowed water to squirt thru the hole and up. Could this cause the vibration? :redface: If not could someone point me in the right direction?

Please and thank you.

 

[Adirondack]

Re: Vibration from I/O (not sure from where)

Hi all, OK after replacing: I/O Alfa one (all brand new including u-joints), lower shift cable, all the bellows, G-bearing. Greasing all zerk fittings on gimbal housing (with marine grade) and a rough shift cable adjustment, I took her out for a test run. Results: (Note, I am following manufactures break-in procedure to the letter) I found fwd gear nice and quite going into and out of gear. At the dock, reverse the same. After running awhile and testing reverse I found it hard to get out of reverse and not at the right spot in shifter. ( ok just some adjustments to do nuff said). However running her at 3500 rpm and trimmed all the way down, I get a vibration kind of like my truck on a dirt road, (subtle but absolutely there). Now while running the engine in neutral I brought the trim up for a look and noticed that I forgot to put the trim tab bolt in (never had a trim tab, looks as thou would hit prop. Only had the allen bolt installed) , this allowed water to squirt thru the hole and up. Could this cause the vibration? :redface: If not could someone point me in the right direction?

Please and thank you.

Tuff to tell what your vibration is. One question would be when you replaced the drive did you also put on a new prop, or have your old one reworked? If not that could easily cause the "subtle vibration" you describe. Also when the drive was installed did you check the motor alignment with the proper tool?

Of great importance is that the "trim tab" you are describing is most likely actually the anode. Put that on NO MATTER WHAT or every dime you spent on your nice new drive will be wasted in pretty short order. The only way I can think of that causing the vibration is if the bolt is in there rattling around against the casting from the moving water.

 

[Bifflefan]

Re: Vibration from I/O (not sure from where)

Did you align the motor before you installed the new drive?
There may be an issue with the coupler starting to go out.

Also, dont tilt the drive up passed full trim when it running, its not good for the u-joints.

 

[Wanshot]

Re: Vibration from I/O (not sure from where)

OK, First Im sorry if I mis-speak terms or part names:redface:, Im going from a copy of "MerCruiser service manual #6". They refer to it as "trim tab" (for steering adjustment, if I am reading it correctly{disclaimer: Im a dumb ol hillbilly}). Now as far as alignment tool, I never removed engine or transom plate, only outdrive and bell housing. Does this still require tool? If so the answer is no, as I read Installing Drive, didnt see it mentioned (however as stated above "Dumb-Ol-HillyBill" still applies). As far as prop, fairly new Solas 15x19 stainless steal in very good shape , once hit a small rock and file'd off the small burr it made so dont think that would be it. Other question, with said prop size, would the Trim Tab/anode fit? Cause to me, it looks as a big No can do.

 

[Bifflefan]

Re: Vibration from I/O (not sure from where)

Any time you remove the drive it a good idea to check the engine alignment. The mounts can wear and settle a bit, also I think I saw that you replaced the Gimble Bearing, and you really need to align it after that. Check This link for what the alignment tool is.

There are alot of threads on how to align the engine, just search "engine alignment" and you should get a ton of them. You can "you-tube" it also.

For the steering trim tab, there is an offset one you can get that wont hit the prop. I have one and they work great. when you install it, standing at the rear of the boat facing forward you want the rear of the tab to be just a tad bit turned to the left. Just a bit will do.

 

[Adirondack]

Re: Vibration from I/O (not sure from where)

OK, First Im sorry if I mis-speak terms or part names:redface:, Im going from a copy of "MerCruiser service manual #6". They refer to it as "trim tab" (for steering adjustment, if I am reading it correctly{disclaimer: Im a dumb ol hillbilly}). Now as far as alignment tool, I never removed engine or transom plate, only outdrive and bell housing. Does this still require tool? If so the answer is no, as I read Installing Drive, didnt see it mentioned (however as stated above "Dumb-Ol-HillyBill" still applies). As far as prop, fairly new Solas 15x19 stainless steal in very good shape , once hit a small rock and file'd off the small burr it made so dont think that would be it. Other question, with said prop size, would the Trim Tab/anode fit? Cause to me, it looks as a big No can do.

I think I do remember the manual calling it a trim tab. It is in fact much more. If the prop has been hit it couldn't hurt to have a prop guy look at it. If the anode/trim tab doesn't fit you have the wrong size prop. Try it. Looks may be deceiving. Anodes are cheap, and available anywhere anyone has to do with boats. Pound for pound the best money you can spend on your boat. Running without it will not change your performance in any noticable maner, but it is part of the drives system that prevents corrosion. Without it electrolisis will eat your drive up. When you put it on make sure the mated surfaces are really clean to facilitate the best conduction possible.

Alignment is critical from motor to drive. You had old parts mated to old parts before. Tolerance for slight misalignment may have been acceptable. Tighten things up with new parts, and that can change. You may also have always had the vibration, and didn't much notice it. Now that it's a new drive it's unacceptable.

I'm grabing at straws here going on the assumption that everything in the new drive is 100%. I vibration is tuff to feel even over a high speed internet connection.:redface:

 

[Bifflefan]

Re: Vibration from I/O (not sure from where)

If the anode/trim tab doesn't fit you have the wrong size prop.

No, There is a standard and an offset tab. Both are correct, you need the offset when the prop rake is to much for the standard one. See the link below.

Merc trim tabs.

Trim Tab.

 

[Wanshot]

Re: Vibration from I/O (not sure from where)

After doing ALOT of reading in the troubleshooting section of the manual, one cause could be gimble bearing cocked. Will be checking that before I go out again. However, if it was the bearing would I not feel it all the time? (w/ muffs on in driveway? Thanks again guys I really appreciate all this advice

 

[Adirondack]

Re: Vibration from I/O (not sure from where)

No, There is a standard and an offset tab. Both are correct, you need the offset when the prop rake is to much for the standard one. See the link below.

Merc trim tabs.

Trim Tab.

My bad. I stand corrected. I have never seen the offset trim tab. Of course running the same boat for as long as I have I never had to deal with prop size issues. What I had was good and got replaced with the same.

 

[Adirondack]

Re: Vibration from I/O (not sure from where)

After doing ALOT of reading in the troubleshooting section of the manual, one cause could be gimble bearing cocked. Will be checking that before I go out again. However, if it was the bearing would I not feel it all the time? (w/ muffs on in driveway? Thanks again guys I really appreciate all this advice

Not necessarily. Things change under load. You said you get the vibration running under high speed. Can't duplicate that in the driveway. While your checking the bearing run an alignment tool in just to be sure. Only takes a minute to get some peace of mind.

 

[Bifflefan]

Re: Vibration from I/O (not sure from where)

My bad. I stand corrected. I have never seen the offset trim tab. Of course running the same boat for as long as I have I never had to deal with prop size issues. What I had was good and got replaced with the same.

Not saying it was your bad, just letting you know. If we all knew everything the world would be pretty boring.