Vibrations in a 1972 Merc 140

[timber-wolf]

I'm fairly new at boat repairs I've been around it for years but this is the first problem that i've had that I don't know...<br /><br />I'm getting very bad vibrations in Drive & Reverse and slight vibes in neutral.. I pulled the prop off because last time I went to the lake I believe the vibes caused a chunk of a previous repair on the prop to break off.. I was hoping that was all it was but without the prop on I have the same issue. I checked the motor mounts and they look good, but I can barely see the back two but, the motor doesn't seem to vibrate very bad it seems like it's in the outboard more so than the engine but what really throws me is that I get the vibes in neutral also just no where near as bad.<br />The boat is:<br />1972 17.5' Tri-Hull<br />4 cylinder 140 HP I/O<br />I just gave it a tune up the beginning of summer.<br />New points, cap, rotor, plugs, changed the oil, greased everything... The only thing I didn't do was change the oil in the outboard. I didn't have it out at all last year, and the first time I took it out this year it didn't want to stay running but the tune-up seemed to have remedied that... <br /><br />Thanks,<br />Chad

 

[Trent]

Re: Vibrations in a 1972 Merc 140

Time to pull the drive and check the u-joints. Worn out joints will cause this problem. While you have it off check the gimble bearing and coupler for wear.

 

[timber-wolf]

Re: Vibrations in a 1972 Merc 140

After I read the forum and did a few more searches on the net, I came up with the gimbal bearing. I had forgotten until I read it on the net but the sound and vibes get a lot worse with hard right or left turns. Also the boat has been "leaking" the last few times i took it out right were the stern drive ataches to the boat. according to another article I read this is caused by the bellows.. <br /><br />The gimbal bearing I figured out but the bellows lost me. are there any good right ups on replacing these?<br /><br />the u-joint will definattely get replaced also while it's apart though..<br /><br />Thanks,<br />Chad

 

[Trent]

Re: Vibrations in a 1972 Merc 140

If it gets worse in left or right turns the problem is the u-joints. Now if your getting water thru the bellows plan on replacing the gimble also. Check these links out, I think they will help you alot.<br /><br /> Gimble Bearing Replacment <br /> Bellows Replacement<br /> Parts <br /> U-Joints <br /> Bellows <br /> Drive Mounting Gaskets

 

[timber-wolf]

Re: Vibrations in a 1972 Merc 140

Great Thank You Trent!!!! That was exactly what I was looking for. I guess it's time to break out the service manual get my moneys worth out of that also... Hopefully I'll be back in the water soon!!<br /><br />Chad

 

[flashback]

Re: Vibrations in a 1972 Merc 140

Trent has the right idea, most likely it is the U joints......good luck

 

[timber-wolf]

Re: Vibrations in a 1972 Merc 140

Sorry for the long reply but I have a few more questions...<br /><br />Well I pulled the stern drive last night and the gimble bearing fell out in more peices than I could count on two hands.. The U-joint bellow had a nice wear spot on the outside with a hole all the way through it also (that should account for the leakage).. <br /><br />My next problem is.. Onnce the gimble bearing shattered I guess it let the driveshaft flop around and broke some of housing off and a chunck of the snap ring that holds the gimble bearing retainer in. is this going to be a problem? <br /><br />I can still get the bellows all the way on and the retainer ring looks ok so I should be able to just put a new bearing in and go right? <br /><br />Also do I have to pull the shaft out of the stern drive to replace the u-joints? it looks like a very tight fit to get them out with it still attached. There's an odd looking ring that may get in the way.. (The ring that screws into the sterndrive and holds the driveshaft in place)<br /><br />I forgot one other thing.. The oil seal behind the gimble bearing has several tears in it.. It's not bad enough that I wouldn't reuse it if I had to but is it easy to change?? any good write ups on that? The service manual was no help to me on this unless I was looking in the wrong section..<br /><br />Thanks,<br />Chad

 

[flashback]

Re: Vibrations in a 1972 Merc 140

Chad, I can,t tell you weather your casting is any good or not without seeing it. but obviously what most likly happened is the U-joints gave up which would destroy the gimbal bearing, bellows, and most likely the coupler. the problem you have is that if you replace all the known broken parts with new and then connect your upper drive with part of the casting missing, you may destroy all the new parts you just installed. I would try to find a new upper unit and just go ahead and bite the bullet..........good luck

 

[timber-wolf]

Re: Vibrations in a 1972 Merc 140

Not what I wanted to here... I snapped some pics when I tore it down so maybe I'll post those after I have them developed if they turned out good enough to see the casting. <br /><br />Thanks for all the help!!

 

[Walter]

Re: Vibrations in a 1972 Merc 140

This is definitely not a call to make without seeing it. You want to insure the gimbal housing is sound before you start spending the big bucks on new parts. Purchasing another gimbal housing & possibly drive housing may be the best way to go. Either have a qualified MerC tech. look at it...or get those pics posted so we can see how it looks.<br /><br />Walt