Hey Spareparts

[cfelton]

Ive got a little vibration when im running along slow to mid throttle. The outdrive was completely rebuilt before I got it. The U joints and all were replaced. I rebuilt the engine, engine bed stringers and transom, installed engine and lined it up using a merc alignment tool. It slips in really easy, so i believe it is correctly aligned. Could the imput shaft be out of balance? I can trim it up when it gets up on plane and it smoothes right out. If I trim it back down it grumbles a little. Forgot to tell ya I rebuilt the whole gimble section, new gimble brg. boots, hinge pins,top and bottom swivel pins and brgs. What do ya think, it feels like the imput shaft is out of balance or something. I dont want to screw up what Ive already done!

[spareparts]

one of the problems they had with those big 4 cylinders was that they did vibrate at lower rpms, is this a new vibration? one that wasn't there before? Or has it been doing it all teh time? A couple of things to check is the front and rear motor mounts. Make sure the rear are tight and the front lags are still secure, check that single isolater on the front mount, make sure the nuts haven't vibrated loose or teh isolater itself is bad. Use a pry bar and see if you can move the engine up and down from the motor mount.

If everything checks out OK, I wpould suspect the coupler, next time you have the drive off, stick the alignment shaft in the coupler, then rotate the engine 90 degress and check it again, do it 2 more times. mercury told me to crank the engine(with a water supply hooked to it) while the alignment tool was still in place, and check it for wobble. you can really fine tune the alignment this way.

[cfelton]

Thanks Spare, The rear motor mounts are new, the front one is original. When I aligned it, I turned the engine over 90 degrees and checked it again and one way it was a little tighter than the other. Its probley the coupler. Everything else is new. I noticed it the first time I started it up after the rebuild. Its not terrible but noticeable, It makes my old compass spin round and round.

[spareparts]

those couplings aren't the most precision things around, you could replace it with a new one and not get a bit better. If everything checks out, just keep running it. remeber, 4 cylinders can't be completly balanced without a balance shaft. The big 224 cu in motor of yours can shake your fillings out when everything is perfect. Just thought of one other thing, are you having any charging problems? I've seen the magnets in the balancer slide around and cause problems, it could throw the balance off. Whenever I change one out to an altenator, I allway knock the magnets out berfore replacing the balancer

[cfelton]

Well it cant be that, it had been converted to an external alternator before I got it. I recently changed out the camshaft seals and checked the back of the harmonic balancer and the magnets were gone. I just looked on a Breezeworks site and found a 97432A1 coupler for 109.00. Thats less than half of everyone else. Do you know if these are used or not? Id rather have a new one if I got to go through all the trouble to install it.Most are around 209.00. Do you know of any cheaper new ones? Thanks Spare!

[THEFERMANATOR]

The 250 SEARAY I redid last year would vibrate pretty bad as well when trimmed in hard. Smoothed right out when you trimmed it to a neutral position. This was with a V8/ALPHA 1 combo.

[spareparts]

Ferm brings up a good point, most boats will create a resonance when trimmed all the way in, I don't know if its cavitation or just vibration going thru the drive, but once you trim it a little, it quiets down, certainly would be cheaper than any other solution. How bad is this thing vibrating? Is causing you mixer to go flat? Rattleling the wax out of your ears? or just a slight annoyance that you notice only because you worked on it

[cfelton]

It rattles anything light laying loose in the boat like a fishing rod laying up against the gunnel. Its really not terrible but definately noticeable to me and others in or out of the water. It makes my old Ritchie compass spin around. But after I get underway I trim the drive up till the bow almost bounces and it goes away. My buddys 86 v20 with the same motor and drive is smooth as silk all the time. If I can get over Christmas I might buy me a new coupler and change it out. I dont think it will be to bad of a job. I think I can do it without pullin the motor out, just support the rear , pull the outdrive and crawl back there and unbolt it. Probley gotta pull the bellhousing off.

[spareparts]

pull the drive and make sure you don't have one of your u-joints binding, while you have the drive off, try the alignment shaft/engine running trick

[cfelton]

Ive checked the u joints, the're new and move freely. Ill try the alignment tool,wobble thing when I pull it next time. Thanks Spare!

[cfelton]

Well, I found my vibration! I went to check the alignment on my 170 Merc/ Alpha one drive yesterday and I reached in and grabbed the drive shaft and can shake it all around. So my coupler is shot! I ordered one last night, 226.00 with shipping. Maybe this will take care of the vibration I've been feeling since I rebuilt the motor and drive. Seems its always something! This is the ONLY thing I havent replaced!!!! Will probably take a good day ta pull the motor and drive and get it in. Gotta get it right really quick, we are headed to Nags Head in 2 weeks!! Cant wait, We need a good vacation!!

:sun:

[THEFERMANATOR]

The couplers on those are known to fail, aftermarkets are readily available for them.

[Big Grouper]

Is one of your prop blades dinged or nicked? Trimmed all the way in is running the prop at an angle that will bring to life any imperfections.

[cfelton]

Im pretty sure its the coupler. It vibrates when running on the water hose in the yard, with the drive in neutral. I can shake the drive shaft inside the coupler. Does anybody know what the torque is suppose ta be on the rear motor mount bolts and the torque on the single nut on the front motor mount ? I cant find the torque settings for these mount bolts in any of my manuals.Thanks!

[spareparts]

I can't remember what the torque spec was on those bolts, we rarely used a tourqe wrench on the rear bolts as most engien compartments didn't allow room for a straight extension and a torque wrench. I ususally had to settle for a swivell socket and my 3/8 impact. If I had to guess, arond 45-55 ft/lbs.
you kind of lost me on your description of whats going on here. You say you can reach in and move the drive shaft? Meaning you can reach behind the motor, between the transom and the engine bell housing and move the drive shaft? If you can do that, yeah sounds like you found your problem. You should also be able to look into the coupling hub with a flash light(drive removed) and inspect the splines in the coupler, they should be uniform with square peaks, if they look sharp on the peaks, the coupler is worn out, don't forget to check the input shaft for wear as well. The splines should bear square in shape as well, if they look sharp on the peaks, its worn. When r[placing the coupling, or any time the drive is removed, use specified drive coupler grease on the splined shaft

[steplift20]

just my 2 cents
hows the prop is it bent or damaged look at it maybe thats the problem

[cfelton]

The prop is a new stainless prop, with no signs of damage and it vibrates in neutral ,on the hose , sittin in the yard . Ive almost ruled the drive and prop out. I can reach over and behind the motor and grab the drive input shaft and shake it around inside the coupler, so im thinking thats gotta be the culprit. This old 77 V has alot of room around the back of the motor but I think Ill just pull the motor completely out ta change out the coupling. Looks like I gotta pull off the engine bellhousing to get at the coupling bolts and ta get it out of the bellhousing hole. It won't be to bad of a job being I already had it out before. Probably can do it in a day (I hope).Thanks for all the info fellas! Ill let you all know how it turns out.

:beer:

[spareparts]

if you can move teh drive shaft like that, I would have to agree that its teh coupler, most of yhe boats i work on you can't get back behind there. Double check the gimbal bearing while you have the drive off

[cfelton]

Will do!!! I replaced it when I rebuilt it but Ill check it out good when I pull the drive. Thanks again!!

:hi:

[macojoe]

I blew a coupler one time in my 165 I/O and it was also the only thing I did not fix when I pulled the motor! It was at least easier to pull the motor the 2nd time:nut:

[cfelton]

I got my new coupler today. Its made by Mallory, hope its ok. Looks right . Did'nt realize it was so lightweight. I guess the outer assy is aluminum also. I'm shooting for Friday ta install it. I think I can just hold up on the rear of the motor, unbolt the bellhouseing and get right to it. I've got right much room around the back of the motor.

[spareparts]

Yeah, Mallory got in the marine parts business a little while back(my wife works for a parts wholesaler). They look like decent parts, on par with GLM and Sierra. Make sure you set the alignement after you get it back in, grease up the input splines as well. What do the splines on the drive shaft look like? hey should have square tops, not sharp, clean the splines out with a pointed object(get all the old grease out of the splines) adn inspect them before you put it back together

[cfelton]

Well, I pulled the outdrive and then the engine friday morning. after looking and comparing the couplings the old coupling wasn't worn as bad as I thought . The splines on the drive shaft looked like new. I found a couple of engine bellhousing bolts loose and the front mount adjustment nuts had worked loose too! After replacing the coupler I borrowed an alignment tool and realigned everything. It seems to have almost entirely eliminated the vibration. I havent taken it out for a good test but it ran pretty smooth on the hose. It took the better part of Friday but I think it will be worth the time and work!!
:sun:

[bradford]

Good Job Brotha! :beer: