2007 Tahoe Q6, 4.3L MPI, alpha1 lower unit, new vibration on acceleration

[gt2003]

I've had this boat out 4 times since I bought it in late July. I've had absolutely no motor issues. We go out this morning, trip #5, and all is good. I idle out to open water then accelerate and run for 5-10 minutes, some at WOT. I'm adjusting trim up and down to see what speed I can achieve. All is well, I make a final left turn, not too tight but not too wide, when I start slowing down, the boat rattles/vibrates pretty intensely. I shut it off, let it sit, checked gauges, check oil, bilge etc, all is good. I restart the motor and it knocks 4-5 times but then stops. I put it in gear and it is fine up to about 1200 RPM's. Whenever I give it any kind of gas though, it vibrates/shakes. We limp back to the dock at just over idle, about 1200 RPM. I try a couple of times to give it a tad more gas and same thing, vibration. I don't know if something happened in the turn and something vibrated loose or what. I'm just asking for ideas on what it could possibly be and where I should start looking. My girlfriend noticed that when she was in the boat getting ready to trailer it, she turned the steering wheel to the right all the way and it started rattling again. Once she turned back to the left just a bit, it stopped rattling. I'm trying to give as many details as possible as the boat is new to me. Please ask if there is any further info. needed. Thanks

 

[alldodge]

I've had this boat out 4 times since I bought it in late July. I've had absolutely no motor issues. We go out this morning, trip #5, and all is good. I idle out to open water then accelerate and run for 5-10 minutes, some at WOT. I'm adjusting trim up and down to see what speed I can achieve. All is well, I make a final left turn, not too tight but not too wide, when I start slowing down, the boat rattles/vibrates pretty intensely. I shut it off, let it sit, checked gauges, check oil, bilge etc, all is good. I restart the motor and it knocks 4-5 times but then stops. I put it in gear and it is fine up to about 1200 RPM's. Whenever I give it any kind of gas though, it vibrates/shakes. We limp back to the dock at just over idle, about 1200 RPM. I try a couple of times to give it a tad more gas and same thing, vibration. I don't know if something happened in the turn and something vibrated loose or what. I'm just asking for ideas on what it could possibly be and where I should start looking. My girlfriend noticed that when she was in the boat getting ready to trailer it, she turned the steering wheel to the right all the way and it started rattling again. Once she turned back to the left just a bit, it stopped rattling. I'm trying to give as many details as possible as the boat is new to me. Please ask if there is any further info. needed. Thanks

Sounds to me to be U-joints or gimbal bearing, first choice would be U-joints. Need to pull the drive off and have a look. Did you pull the drive and check things this season?

 

[gt2003]

No, I didn't. I've just had it for about 2 1/2 weeks. It ran well when we went for a test drive with the previous owner and has run great the last 4 times we've had it out. The previous owner "said" he kept it serviced but maybe not. Any idea what kind of cost I'm looking at if I have someone do it for me? I know it probably won't be cheap but hey, if it's fixed then that's one less thing to worry about.

 

[gt2003]

I called my local marine shop, a guy who has been in town ever since I've been here, $600 is what he quoted me to pull the drive and replace the gimbal, u-joints and impeller. I figure since it's in the shop, might as well have it done! From reading around, this seems quite reasonable.

 

[tpenfield]

+ 1 on the ujoints being suspect. However, the shop should check both gimbal bearing and u-joint to be sure. . . .

as a Do It Yourself, u-joints will be in the $50 range and if it was the gimbal, that would be in the $75 range. I assume you were quoted $600 for just the u-joints?

 

[NHGuy]

It does sound like the gimbal and/or ujoints are your problem.
You may already have done this, but have your technician verify the problem/solution. Don't just change the parts til you know what is failed. And yes, do the impeller if he has the drive off.
Nothing will sour your relationship with what could be a good mechanic more than a failed guess diagnosis. Get his input, maybe he will want to show what is found wrong.

 

[gt2003]

The $600 was the quote for all 3 if done at the same time. Since I don't know the history of the boat, I thought it might be wise to have him change all 3 out while he is in there to prevent further issues in the near future. I will have him confirm the diagnosis prior to doing the work. Does this sound like a good course of action? I'd rather spend the money now if these things will likely need replacing in the future.

Anything else "preventive maintenance" that he might do while he is there? Bellows maybe? I'm just thinking that it probably hasn't been done and has definite potential to go south in the future. Just wanting to get it all done at once so I've likely got a few years of only minor maintenance provided I do my part. Thanks again to everyone. Looking forward to your replies.

 

[alldodge]

The $600 was the quote for all 3 if done at the same time. Since I don't know the history of the boat, I thought it might be wise to have him change all 3 out while he is in there to prevent further issues in the near future. I will have him confirm the diagnosis prior to doing the work. Does this sound like a good course of action? I'd rather spend the money now if these things will likely need replacing in the future.

Anything else "preventive maintenance" that he might do while he is there? Bellows maybe? I'm just thinking that it probably hasn't been done and has definite potential to go south in the future. Just wanting to get it all done at once so I've likely got a few years of only minor maintenance provided I do my part. Thanks again to everyone. Looking forward to your replies.

Don't see you needing boots, but something happened to have the U-joints or gimbal go out. The mechanic will be able to check the boots while doing the work. My 1995 Rinker has never had the boots changed, but it does spend most it's time on a trailer, and the drive is most always full down. Your 2007 should be in good shape.

 

[gt2003]

Thanks AllDodge. I'm taking it in mid-week. Boots look good from what I can tell. Aren't the gimbal bearing and u-joints a fairly common maintenance type thing that might need to be replaced after 7-8 years of use? Just trying to become more informed. Thanks

 

[gt2003]

UPDATE! I got a call from the boat shop this morning. He said my gimbal had pretty much disintegrated! I ran down to the shop at lunch. IT'S UGLY! The ONLY thing remaining of the gimble bearing is the outside ring and only about 1/4 the width of the original. He's done boat repair 30 years and says he's run into this one other time and was able to repair it but the trick is gettting the remainder of the ring out without harming the aluminum housing. He said if that happens he'd have to pull the engine to repair. My boat is the one "up for repair" now so they're going to work on it until it's finished. He did mention that I was very lucky that I didn't tear up the "upper" ring (maybe) of the lower unit or that would have been very costly. He also mentioned that I'm lucky we limped back in as we could have done very extensive damage if we tried to go any faster.

 

[gt2003]

QUESTION for my learning only: When I tried to give the engine gas and it vibrated horrendously, was that they yoke beating the gimbal bearing to death? It's the only thing I can think of and picturing it in my mind, it makes sense.

 

[tpenfield]

If the bearing disintegrated to the extend described, then it would not hold the drive shaft in line with the coupler and therefore a fight would ensue between the u-joints and the coupler as to who is gonna get 'their' way.

this would cause a lot of back and forth action, and perhaps the yoke would get involved and come in contact with the gimbal bearing, etc.

 

[gt2003]

It disintegrated to that extent, lol. It almost looks like the gimbal bearing was removed and someone replaced it with a hoop earring. NOT PRETTY! Thanks for the explanation. I'm hoping he is able to get the remainder of the bearing out soon and successfully!