Bravo 3 method to confirm coupler is gone?

[IdahoDoug]

Hey, first post and thanks for all the great info. Been reading here since Friday when this happened and officially joined today.

1997 7.4L MPI with Bravo 3. Friday evening was leaving the marina to head out to our favorite anchorage. Idled out until engine warm and rolled into the throttle as normal when just before planing the engine seemed to go into neutral, accompanied with a slight whining sound that changes with engine RPM. No bang, no other drama, and shifting in and out of gears gets nothing - not even slight thrust. All fluids fresh and full. 550 hours and I lube annually (bought new), and change the outdrive oil with correct Merc gear oil also annually. Both those zirk fittings on the coupler also get hit every season.

Pulled the upper end of the lower cable off and manually moved it back and forth with the engine running again briefly and it felt correctly "notchy" as though I was shifting something at the other end - did not feel like a broken cable with zero effort.

Based on what I read here, it sounds like the coupler went and that I was fortunate to get as many hours as I did. I do all my own work so I'm looking for a way to confirm it is the coupler before I order the $$ part and pull the engine. So, to my question.

I can easily see the coupler and the outdrive's shaft coming into it. When I start the engine, with a good coupler the engine should be spinning that shaft at engine crank speed, correct? If it is not spinning, then the coupler would be shot, right? With the advantage of being able to see the shaft on my boat, can anyone suggest a definitive test?

Thanks, it's incredibly bad timing for this. We have 2 young kids from Italy coming to stay with us for 3 weeks. They'll be here in 3 days and the marinas are all booked out for a month. I do all my own work and I just need a definitive test on the coupler before I find a tree strong enough for a big block.....

 

[picklenjim]

Re: Bravo 3 method to confirm coupler is gone?

Yes you are absolutely correct, it should be spinning the shaft at crank speed. You say you don't get any thrust at all shifting in and out of gear and you can easily see the coupler and shaft. I would put it in the water, start it and have someone shift it in and out of gear as you watch it. If it's not turning the shaft with the coupler then start looking for a tree.
Here's a link to the best one you can get and it's $150 less than one from merc.
http://www.cpperformance.com/c-278-drive-couplers.aspx

You will need to put it in the water so you have a load on the prop.

 

[Pete104]

Re: Bravo 3 method to confirm coupler is gone?

If you can see it as easily as you claim, it'll be a piece of cake. Just do it without any distractions!

 

[muc]

Re: Bravo 3 method to confirm coupler is gone?

Yes the shaft should spin at the same speed as the engine.
But you should still pull the drive and look at the coupler and shaft before you order parts.
MerCruiser recommends that the shaft be replaced at the same time as the coupler. You need to look at it and decide if it has too much wear --- there will be wear.
If you plan on keeping the boat for awhile and you spend a lot of time at idle/slow speeds --- 7.4L engines wear out couplers at idle/slow speeds --- I recommend that you install a steel spline (heavy duty) coupler and new shaft. Part number 861523A11 is my guess but you didn't post engine and drive serial numbers so I can't be sure.
The coupler listed by picklenjim will work but it has aluminum splines. It isn't the ?best? you can get. It also doesn?t have the ?snout? that seems to hold the grease in better.
After having replaced more than a few couplers. I also recommend that you check the flywheel and new coupler for run-out before you reinstall the engine. Its no fun pulling the engine twice due to getting a bad brand new coupler and it seems that 1 out of 20 are bad out of the box. But maybe I'm just not lucky?
Alignment is important so take your time and get it right on after the engine is back in the boat.
Depending on how easy things are to get to on the engine in your boat there are a few things you should think about doing while the engine is out of the boat.
The manual has a lot of good info --- suggest you read it before starting dis-assembly.

 

[IdahoDoug]

Re: Bravo 3 method to confirm coupler is gone?

Thanks for the input. I'm going to try to get it to the ramp tomorrow to test. The coupler doesn't show any aluminum dust around or below it or other signs of distress - other than the normal slinging of fresh grease. So, kinda hoping this will be the problem as even a hairy knuckle guy like me can replace a 3 pound part. Just don't want to find out it's something in the zillion little part outdrive...

Will follow up.

Doug

 

[IdahoDoug]

Re: Bravo 3 method to confirm coupler is gone?

Following up to thank you all for the input. My 10yo son came with me to the boat launch to see what we could discern on the shaft/coupler. I'm happy to say it is clearly the coupler as the engine started and the shaft from the outdrive did not move, and I am 99.999% sure it is supposed to turn anytime the engine does. Then engaging FWD did not change anything.

So, I'm breathing a sigh of relief that Mercruiser's durability rep continues to be a huge bonus to me after 15 years of literally perfect operation. Well, actually 14 years as the entire outdrive was replaced by Merc on their dime in the most spectacular customer service example I've personally ever heard of. Now that I'm a member here, I'll have to relate that story because it was really remarkable.

Anyhow, I'll be ordering the coupler as soon as I find a good price for the round Bravo coupler and yanking the engine/drive with confidence. Anybody in the Coeur d'Alene, Idaho or Spokane, WA area have an alignment tool I could borrow?

Regards,

DougM

 

[cr2k]

Re: Bravo 3 method to confirm coupler is gone?

Buy one on ebay. You will need one for annual maint anyway.

Don't know if I would be "Happy" to say it was the coupler. $300 plus drive then engine pull.

While you are in that deep don't forget to look around for anything else you can do while your there.

 

[dubs283]

Re: Bravo 3 method to confirm coupler is gone?

i wouldn't be too happy about only getting 550 hours of use out of a coupler either, your cause of failure had nothing to do with the quality or durability reputation of mercruisers product

the cause of failure was your lack of proper routine miantenance, i.e. pulling the drive every season, checking the alignment, and greasing the coupler/shaft among other items

mercruiser maintenance schedules are based on the average boater putting 100 hours on thier engine/drive packages a season, so in your case you have only used your boat for five and a half seasons - if you do the math you use your boat an average of 36 hours a season, a day and a half of straight boating, 550 hours = 30 total full days (24 hours) of boating

 

[04fxdwgi]

Re: Bravo 3 method to confirm coupler is gone?

i wouldn't be too happy about only getting 550 hours of use out of a coupler either, your cause of failure had nothing to do with the quality or durability reputation of mercruisers product

the cause of failure was your lack of proper routine miantenance, i.e. pulling the drive every season, checking the alignment, and greasing the coupler/shaft among other items

mercruiser maintenance schedules are based on the average boater putting 100 hours on thier engine/drive packages a season, so in your case you have only used your boat for five and a half seasons - if you do the math you use your boat an average of 36 hours a season, a day and a half of straight boating, 550 hours = 30 total full days (24 hours) of boating

I believe he remarked he was "happy to say" because it was the coupler that failed instead of the drive unit going south.

That being said, I agree that proper annual maintenance should have enabled the coupler to last more than 550 hours. My '92 7.4L Bravo 1 had almost 1200 hours and 16 years on it before the coupler needed to be changed. And it was only changed because the engine was out for a gimbal steering problem / replacement and it seemed like a good thing to do at the time.

 

[krisnowicki]

Re: Bravo 3 method to confirm coupler is gone?

Well if you put 550 hours on your boat and are just buying the alignment tool. Thats probably the problem. Make sure it is aligned and the rear motor mounts look good when it goes back in. Also, time to paint the bottom of the engine again to stave off the rust. I just change a coupler on my bravo.

No too bad, the alignment killed the old one. I got a 10 hour used one on ebay for $150.

 

[IdahoDoug]

Re: Bravo 3 method to confirm coupler is gone?

I tried to find it on Ebay but it did not come up. Where are you, and can you send me a link? PM'd you... Oh, nevermind. I am thinking you just mentioned you bought one on eBay. Anyone else have one? Tx

Doug

 

[IdahoDoug]

Re: Bravo 3 method to confirm coupler is gone?

Anybody that has looked at a Bravo 3 coupler happen to be online today? I found a nice used one and the seller sent me a photo of the front and the back. On the back, where the engine's crankshaft fits their look to be about 6 straight cuts around the hole. Are these supposed to be there to relieve strain or does the guy have the gall to be showing me a cracked part? Thanks in advance....

Here's a link: http://www.auctiva.com/hostedimages...,456950575,456949878&formats=0,0,0,0&format=0

 

[dubs283]

Re: Bravo 3 method to confirm coupler is gone?

its probably the hub is cracked and the coupler will fail soon

why don't you just buy a new OEM coupler and be done with it??

see the first line of my signature

 

[IdahoDoug]

Re: Bravo 3 method to confirm coupler is gone?

I see your signature and understand your point of view. In this case, a coupler is a very simple and sturdy part - precisely the kind of part that in my view is OK to find used. And by doing so, I can spend the money saved on fuel for hours of fun with my family on the water. If this were a gearset from the outdrive or similar I'd go new because of the setup time and potential damage to the rest of the machine if it failed. The coupler is essentially a splined shaft spinning in a rubber casing - low tech and durable. So I guess everyone makes their own decision on where to save money. So, to my question - are those 6 cuts supposed to be there, or as dubs283 surmises is the hub actually cracked and the seller has no clue? I have never seen the back side of one and have no idea if those are supposed to be there and am hoping someone can grab one off a parts shelf and see. Thanks in advance to all!

 

[IdahoDoug]

Re: Bravo 3 method to confirm coupler is gone?

Ah, just called the local shop and the one on the shelf has those same cuts - must be a vibration absorption strategy? Interesting design.

 

[IdahoDoug]

Re: Bravo 3 method to confirm coupler is gone?

OK, got the outdrive off and everything looks great. Gimbal bearings tight, CV joint tight and everything's oozing fresh moisture-free grease. Even the O rings where the outdrive mates to the transom fitting (name?) are pliable and lubed.

The outdrive shaft had the expected long remnants of the coupler splines in it's splines and the coupler's interior is perfectly round. So now the boat's at a buddy's garage and centered under a heavy lifting eye. Tomorrow I'll disconnect stuff on the engine and possibly pull it if I have time. Thanks for all the great advice. Our guests are here and I just may get this thing back in the water by the weekend at this rate. Coupler's not here and the seller seems to be a flake so may end up buying one from another source for more $$$. Story of my life on sellers......

Doug

 

[IdahoDoug]

Re: Bravo 3 method to confirm coupler is gone?

Well, engine's hanging a foot off the stringers and I swiveled it around so I can easily access the coupler end. Trouble is, I cannot find after going through the posted online factory manuals where it shows how to get the flywheel housing off. I'm sure I'll get it off but I always feel better when I know how many bolts there are and that there's not some spring loaded seal that's going to shoot off into a corner of the garage. So, can anyone point me to an easy diagram or describ it? The factory manual seems to show only two bolts. Thanks in advance. Part should be here Friday. Doug

 

[IdahoDoug]

Re: Bravo 3 method to confirm coupler is gone?

So, any assistance on removing the large casting on the rear of the engine that hides the coupler? It incorporates the rear engine mount tab eyes. The online engine manual literally has only a tiny diagram and mentions nothing about removal procedure.

 

[picklenjim]

Re: Bravo 3 method to confirm coupler is gone?

Should just be the bolts around the outside perimeter which bolt it to the engine block.

 

[krisnowicki]

Re: Bravo 3 method to confirm coupler is gone?

There maybe a dust shield behind the flywheel that has a series of 3/8 or 5/16 bolts to remove on the back/bottom of the bellhousing.