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Old 23-11-2012, 17:28   #1
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Gearbox stuck

Hello,

I have a Volvo Penta MD7B, and the gearbox seems to be stuck in forward.

I have disconnected the push/pull cable and that is working perfectly. I can move the part it attaches to on the transmission freely, but it will not change gear on the box and does not make any strange noises.

Could someone please point me in the right direction?
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Old 23-11-2012, 17:41   #2
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Re: Gearbox stuck

* Has it got the right amount and type of fluid inside?
* Is it old and tired, or in otherwise good shape?
* With engine off, try turning the prop shaft end ... both ways.

(I'm not familiar with that model ... transmissions have a wide variety of shifting and neutral behaviors)
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Old 24-11-2012, 07:46   #3
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Re: Gearbox stuck

Greetings and welcome aboard the CF, Kiwi.
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Old 25-11-2012, 04:07   #4
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Thanks for the welcome.

The gearbox is old, but seems to be in good condition.

There is new oil in the gear box.

And I can turn the prop both directions
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Old 25-11-2012, 16:46   #5
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Re: Gearbox stuck

Quote:
Originally Posted by thekiwi View Post
Thanks for the welcome.
The gearbox is old, but seems to be in good condition.
There is new oil in the gear box.
And I can turn the prop both directions
Remove, repair, replace.

The local boats here have no gearbox at all. When they want to go they pull the rope and go. Even big boats. Reverse is a bamboo pole...
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Old 25-11-2012, 17:45   #6
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Sounds much easier.


Thanks, much appreciated. I will remove and repair the box!
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Old 25-11-2012, 17:54   #7
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Re: Gearbox stuck

Quote:
Originally Posted by thekiwi View Post
And I can turn the prop both directions
If tranmission was stuck in gear you shouldn't be able to turn prop (at least without turning the engine over as a result).

Maybe diagram below can help
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Old 25-11-2012, 23:01   #8
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I thought it was stuck in gear. Obviously I was wrong. Although it certain goes forward !!!
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Old 27-11-2012, 10:29   #9
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Re: Gearbox stuck

Take a flashlight and watch the shaft that the shift lever is attached to. Make sure the shaft is turning when the lever moves. There could just be a loose clamping bolt on the lever. Check the simple stuff before tearing it apart.____Just another 2 cents worth._____Grant.
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Old 27-11-2012, 16:40   #10
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Thanks Grant, I will check that. It sounds like a likely fault. Luckily I haven't been out to the boat yet!
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Old 17-12-2012, 04:03   #11
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Re: Gearbox stuck

Here is a pic of it ... something amiss not sure what it is...
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Old 17-12-2012, 04:16   #12
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Re: Gearbox stuck md7a

Here's some pics... something seems to be amiss?
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Old 17-12-2012, 05:10   #13
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Re: Gearbox stuck

Slightly educated opinion. It looks like cone clutch shifting and the fork that moves the cones back and forth is just plain worn out/missing. If you could replace the worn out/missing shift parts it might run for a while after a good flush to remvoe any metal bits floating around but likely needs rebuilt since that amount of wear doesn't bode well for the other components inside. The cone clutch uses a helix cut gear to tighten when the engine is turning so that may explain why you can spin the shaft with the engine off.
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Old 17-12-2012, 05:37   #14
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Re: Gearbox stuck

Greetings and welcome aboard the CF, greyim and bglad.
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Old 31-12-2012, 19:40   #15
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Re: Gearbox stuck volvo penta md7a

Added a little bronze
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