Knocking noise on 7.4l Bravo III

sounds good then. the nice thing for gerry and i, was as we travel a lot with the boat.
our warranty was good at any mercruiser dealership

our drive also came with a full set of new anodes and had the new style drilled and taped back prop drive shaft, to use the newer extra prop anode. not a big deal. some one on the 4-m here, turned use on to a rear prop nut that you can bolt the anode to.
 
garryowen said:
sounds good then. the nice thing for gerry and i, was as we travel a lot with the boat.
our warranty was good at any mercruiser dealership

our drive also came with a full set of new anodes and had the new style drilled and taped back prop drive shaft, to use the newer extra prop anode. not a big deal. some one on the 4-m here, turned use on to a rear prop nut that you can bolt the anode to.
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Thanks for the advice, I'm feeling a bit better about it now. I was upset that they didn't inspect this a bit more the first time that we brought it in, but since it wasn't making any noise at that time, I guess I can see their position about not tearing down a working unit.

I'll check with them to see what a reman'ed drive would cost. They stated that it's still cheaper to rebuild my existing one, but I don't know how much though.

Are the rebuilt drives a newer version than what I currently have? (1998, so gen 1?)

--Mike
 
the one i bought was built back to current factory specifications (any change in or difference in parts and were the same as you would get in a new drive). i cant tell you for sure how old the doner drive was.

the one i got was a warranty replaced drive. in other words it failed under warranty and was switched out with another drive. then sent back to M-C and rebuilt at the factory.
they then go out for warranty replacement or sale as factory rebuilds.

as i remember--when i bought it, it was 1500 or 2000 cheaper than a brand new one. at the time it worked out to---- the rebuilt drive and new transom assembly was the same price as new drive. i want to say mine had all new internal parts but i don't remember that for a fact.

it came with a new drive shaft and u-joints and full of oil. ready to run
 
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Cool, thanks for the info. Right now my wife is trying to bust their balls to get them to cover more of this repair. Her argument is that we reported the noise while still under their 30-day warranty, so they should have torn it down then to inspect it. No clue why the noise went away for almost 8 hours of running though.

Any opinions on how a drive would fail this way? Basically they said the forward gear lost teeth, which then went throughout the drive. The dealer says either banging back and forth between gears at too fast a speed, or coming out of the water and not throttling down. Neither of those have happened on my watch, but we've only put 18 hours on the boat, so who knows what the previous owner did to it. I know drives fail all the time, and sometimes without any real provocation, it's just disappointing that we got so little use before a major repair was needed.

Also, is there anything else that I should have replaced while the drive is off? I had them check the u-joints, and they said they were replaced when they did the gimbal bearings and engine coupling. Anything else?

Oh well, hopefully they can have it back together before Labor day, I'd hate to lose any more weekends.

--Mike
 
Basically they are paying for the labor at shop rate and you are paying parts. If you go with a reman then their cost will be more and labor less and they will want the difference from you.

Take the deal and get the warranty. IMHO.
 
OldSkool said:
Basically they are paying for the labor at shop rate and you are paying parts. If you go with a reman then their cost will be more and labor less and they will want the difference from you.

Take the deal and get the warranty. IMHO.
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Pretty much, yes, labor was 1600, parts were 2732 plus tax, so they were probably also giving me the parts at their cost.

I'd have taken the deal already, but the wife is a little hormonal this week and feels the need to argue her point. I'm just letting her go, because it's easier than me arguing with her. I told her to leave my name off the emails, so I could at least have the option to smooth it over if she f__'s everything up.:wow:

--Mike
 
the damage most likely has been done for a while.

could have chipped a tooth and run just as you described. tooth could have gotten caught in some corner and stuck well enough that it didn't cause trouble and quiet drive till it came loose.
at this point your gear train became a coffee grinder for metal and you see the results.

i had this happen on one of the alpha drives we broke. it make a loud pop and killed the motor. stoped dead in the water with the motor locked up.
got into water and prop would turn one way not the other and wouldn't shift.

got a socket on front of motor and tried to turn. couldn't turn over but for what ever reason i tried to turn it backwards and i turned over. this must have released the, later found out broken tooth, wedging the motor.

unpluged the coil and tried the starter. turned ok. started and made some nasty noise a and then quiet-noise-quiet ect. limped back to dock.
pulled and pulled cap on top of drive. broke a tooth and every time it would float in to gear train .......... that little bit of running, and it was pretty nasty. ended up with a cracked housing and a lot of ground up bits . anyway at times it was quiet enough to give hope nothing was wrong. then noise.


as far as what to check with drive off and change. didn't read what all you had done but can tell you when we got our 310 this spring i had the drive pull and changed all the rubber parts---bellows ect, lower shift cable and trim sensors
 
garryowen said:
as far as what to check with drive off and change. didn't read what all you had done but can tell you when we got our 310 this spring i had the drive pull and changed all the rubber parts---bellows ect, lower shift cable and trim sensors
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Yeah, that's what I told my wife, it's likely been damaged for a while now.

As far as what was already done, when they took the boat on trade, they did the following:
-pulled the engine, replaced the coupling
-pulled the drive, replaced the gimbal bearing (and supposedly the u-joints although it wasn't listed)
-new exhaust cuff, shaft bellows, shift cable bellows
-new lower shift cable
-reseal "back-door" seal
-new exhaust shutters

I'm just praying the engine lives a long life, it has 486 hours on it, but the compression numbers were good, and so far I haven't noticed any oil consumption or odd noises. (knock wood) At least a couple years of running would be nice.

--Mike
 
FWIW: In my line of work I rebuild heavy construction equipment power trains. When I see a tooth broken off from a seasoned gear, it most always is from shock loading. You may have lost a small part internally in which went through your gears and snapped one off, if so there would be many witness marks from this small part. Most likely the prop hit something and started the process. May have taken 20 hrs of running or even only a few to eventually fatigue fail the weakened root of the gear tooth. This is why I don't run a stainless prop on my boat.

Why did this noise come and go?... there must have been a place for debris to hide within the case. I would really think the drain plug mag would have shown some signs of this forcoming failure!

Some how I think your Dealer knows all this. And the fact that they are going 1/2's on the repair is marginally fair. How ever, a better deal for all may have been a new drive and you pay 1/2 dealer cost. Now you've got a Merc warr on your drive... jm.02

best of luck with it all.

Sorry for duplicating alot of what was allready said. I was spell checking!
 
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BonBini said:
Some how I think your Dealer knows all this. And the fact that they are going 1/2's on the repair is marginally fair. How ever, a better deal for all may have been a new drive and you pay 1/2 dealer cost. Now you've got a Merc warr on your drive... jm.02
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Yeah, I'm sure they know they missed the problem earlier, although they won't admit that openly. I'm going to check to see what the cost difference is between a reman'ed unit and rebuilding mine. They are a certified mercruiser repair shop, and are offering the same warranty that Mercury does on reman'ed drives, but it's through their shop. I'm not that put off by that though, they have been good to us so far, and have a pretty good reputation. Plus, my boat will never leave the lake under my ownership, I have no trailer, and nothing big enough to tow it with.

Thanks for your insight into the problem.
--Mike
 
mjfrank said:
Pretty much, yes, labor was 1600, parts were 2732 plus tax, so they were probably also giving me the parts at their cost.

I'd have taken the deal already, but the wife is a little hormonal this week and feels the need to argue her point. I'm just letting her go, because it's easier than me arguing with her. I told her to leave my name off the emails, so I could at least have the option to smooth it over if she f__'s everything up.:wow:

--Mike
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I was stopped for a burnt out head lamp one time and all was well until the Admiral asked the officer why he couldn't use his time to pull over REAL traffic violators. Game on at that point.
 
OldSkool said:
I was stopped for a burnt out head lamp one time and all was well until the Admiral asked the officer why he couldn't use his time to pull over REAL traffic violators. Game on at that point.
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:grin: I've learned to just let her go and get the hell out of the way, especially on "that" week of the month.
 
Well, as I thought originally, my wife's powers of persuasion are not all that good. (funny how they always work on me though) She couldn't get them to budge, so I'm stuck paying 50% of the tab on the repairs.

I'm still pissed at the dealer for not catching this while under warranty, but I guess in hindsight I should have pushed for them to at least drain the drive oil and check it. Live and learn. In the end, I guess it's not a horrible deal, I'm basically getting a reman'ed drive with a 1 year warranty for about 2300.00. At least it's one less thing to worry about now.

--Mike
 
mjfrank said:
In the end, I guess it's not a horrible deal, I'm basically getting a reman'ed drive with a 1 year warranty for about 2300.00. At least it's one less thing to worry about now.
--Mike
Click to expand...

My guess is they mis-diagnosed a 'noise' when they changed the gimble and u-joints in the first place. They wouldn't have changed those items for the fun of it... there was a problem. Then you brought it back to them within the warranty period and they missed it again (it was quiet but that doesn't matter)... so they offer to make it up to you by repairing your drive for $2300.
Nope, I wouldn't be happy with that at all.
I think you guys have demonstrated clearly that you bought the boat with this problem. Unfortunately dealers have to 'eat' the odd repair and this is one of those occasions... just my 2 cents worth too.

Either way, it'll sure be nice to put this thing behind you and get back to boating.
 
HI I have the same noise I think.Its coming from behind the motor.Its not a hard clunk.Kinda ticking clunk noise.My first thought was the gimble barring but I had it replaced this season.My second thought is the tranny but it shifts fine and runs fine.Im pulling it out of the water next month and going to have it checked out.
 
Whats a one year warranty worth when you can only use the boat 4 months out of the year.It should be a 3 year warranty
 
sappington said:
Whats a one year warranty worth when you can only use the boat 4 months out of the year.It should be a 3 year warranty
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True, although we can usually stretch the season to about 6 months around here. I'm planning to run the crap out of it over the labor day weekend, and maybe a couple more weekends in September and early October. Plus, I'll basically be covered for the majority of next summer, so it couldn't have happened at any better time. Hopefully for your wallet's sake, your noise isn't the same as our's. The first time, it started as a loud knocking or tapping, way to loud to continue using the boat, but after shifting back and forth between forward and reverse a few times, the noise stopped completely. The second time it happened, it wasn't as intense, like a hard tapping. Under power, the boat almost had a diesel-like rattle to it. Once at the service dock, standing behind the boat with it running, you could hear the noise coming from the outdrive, and by putting your hand on the top cover of the upper gearcase, you could feel it.

And yeah Magster, I totally agree, they dumped over 2500 in parts and labor in it before we even saw the boat, so they were certainly looking for something. Why they never at least pulled the gearcase cover is beyond me. We certainly pushed for them to cover the full cost, but we have almost no proof or leverage. We contacted our lawyer, but he basically said it's not even going to be worth the time, since it's tough to prove the noises were related, we probably won't recover 100%, and the boat will sit for months while it's all being sorted out. (and they'll probably start charging us daily storage fees)

I'm definitely looking forward to Labor day!

--Mike
 
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