Bravo 3 I/O lifts out of the water in reverse

B

Buffo

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Haven't posted here in years! Got out of boating back in 2009 and thought I was gone for good. But my son caught boat fever, so now I'm back into boating again. (Evidently once you are hooked, it's for life!)

Anyway, my Boy just picked up a used 1996 Regal Commodore 256 with a Merc 7.4L and a Bravo 3 stern drive. When he shifts into reverse, the entire outdrive lifts up and the props nearly clear the water surface. When you shift back into neutral, you can hear the drive "thunk" back down into the lowered position.

I seem to remember some sort of reverse-lock-out valve on my old Alpha one, but of course I sold all the manuals when I sold the boat, so I'm lost. Does anyone remember the early generation Bravo 3's? Do they have a similar feature?

Adam (Back again)
 
No reverse lockout, most likely trim pump is out of oil or air bound.
 
Yeah, the older alpha and typeI had a reverse lock-out valve on the shift plate. The newer trim pumps have an internal lock-out. Never worked on the newer trim pumps. I installed the newer pump on my alpha and just bypassed the reverse lock-out mounted on the engine. Swapped the alpha for BII and using the same pump. You can buy complete after-market trim pump for $100.
 
Thanks for all the replies, folks. Sorry for my own late reply - been out recovering from shoulder surgery! (Getting old is definitely not for wimps...)

The pump is not air-locked, and there is plenty of fluid in the reservoir. We've tried working the drive up and down, and sometimes it moves full range, while other times it only moves a tiny bit and then stops.

Thanks for the link to the manual for the trim pump, that should help plenty! One of the guys at the marina suggested that the internals of the pump (or more correctly, the valves on the pump assembly) could be leaking and causing this problem, so having an exploded view and a troubleshooting guide is a big plus.

I looked for the reverse lock-out valve on the shift plate, but I didn't see anything that looked even remotely familiar. In fact, I couldn't even find the ignition shift interrupter! Maybe the Bravo III doesn't use one? I'm sure my old Alpha I had it though, because I had to replace it! This one on the Bravo III looks different though.

I'm hoping to have time later this week to work on it with my son. I think we should start with the pump assembly and see what we find... If we can replace the whole thing for only $100, then to me that's a no brainer! Either way, I'll be sure to post back with the results.

Adam
 
Adam, I can't add much to the reverse lockout discussion, BUT... At least in MerC, only Alphas have Ignition Interrupt on the Shift Plate. The "dogs" that engage gear, forward and revers, are "undercut." That allows engine torque to tighten their engagement. It works, to the point that it won't come OUT of gear unless the engine misses right when you're pulling on the shift cable. Only works under load. Out of the water, shift plate on Alpha shouldn't move going into or out of gear.
MerC Bravos, like Volvos, use a "Cone Clutch" that doesn't need Interrupt. Some oldies in some brands might have used it, but current status is Alpha-Only.
 
Thanks for the tip, j-d! I didn't realize that the Bravo III didn't use an interrupter. So that makes sense that I couldn't find one.

Still need to find the reverse lockout though. Unless it's internal to the pump... I should know more after I spend some more time in the bilge!

Adam
 
If you read what I wrote you'll get an idea about the reverse lockout.

Something a mechanic should do is listen to the pump as it's going up and down. Especially when It's NOT going up or down. Listen if it labors or free wheels.

More than likely the reverse lockout valve is sticking. You could run some paint thinner thru the system...after draining the system.
 
Hey Charlie;

Rest assured, I did read your post. :) I also did some research, both on-line and at the marina, and the consensus is that the Bravo III never had an external reverse lock-out. It's always been internal to the pump. But yeah, had there been one on the shifter, I definitely considered your suggestion to just bypass it and use a newer style pump that had the internal one.

As an aside, it appears that my old Bayliner also had the newer-style pump with the internal lock-out. Not sure why I remembered one on the shift plate, but maybe I was confused between that and the ignition interrupt switch.?. I dunno.

Anyway, my son pulled the entire pump out of the boat yesterday and took it apart. It's got tiny chunks of rubber throughout the internals - as if the thing swallowed an o-ring or two. He also noticed that the oil in the reservoir looked bad. The bottom 1/5 of the tank was filled with jello! Not good...

Several of the O-rings we found intact were damaged. (Flat spots, crushed, etc) and there is a ported sleeve inside the pump assembly that is visibly plugged, but we can't get it to come out of the housing. Probably rusted from years of neglect. (If the quality of the oil in the tank is any indication, this thing has probably never been serviced.) The boat was kept in dry-stack, so it's likely the drive had not been trimmed fully up in a very, very long time.

The rebuild kits we found on-line were all priced at around $100 or so, and we found several brand new pumps (complete with motor and reservoir) for $185. In the end, given the importance of the system now that the boat lives on a trailer and the fact that we couldn't be certain that the pump internals would be OK, he decided to cut to the chase and just replace the whole unit with a brand new one. It should be here Tuesday.

Thanks for all the suggestions everyone! I had hoped to fix the existing unit, and we may try to rebuild the old one at a later date just to have a spare, but for now I think replacement is the safest option. (And certainly the quickest.)

Adam

PS: How long has Boatfix been off-line? Did they go out of business? What happened to George? Sorry if this is old news, but I've been out of the loop for about 8 years...
 
Just to give some closure to this topic; after replacing the trim pump unit the problem was solved, although it took quite a while to work all the residual air out of the system.

Adam
 
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