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does this DP upper sound CRUNCHY?

" some sort of drive failure" ??? some details of the event ( and symptoms) and what made you decide to take it a part would help...

"sound crunchy".... more importantly, HOW does it feel when you do that??? Gears and bearings when dry always make some noise when rotated..
 
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grubtron said:
https://www.youtube.com/watch?v=X6P_TV2d9kM

I had some sort of drive failure last week and the marina said its the upper drive. I want to take it apart and take a look at the gear faces.

VERY NEW to boats so i'm in total learning mode.

Anyway, does this sound crunchy? It doesn't feel very smooth at all.
Click to expand...

It is very tough to tell from the audio via the video.... but from what I can hear, it does sound a bit rough.


Is this a Pre-A or post A transmission?

If Pre-A, be very careful when removing the 4 cap screws.
Use propane torch heat on the area of the thread inserts prior to attempting to remove the 4 cap screws.

If A or later, this is not quite the issue, but I'd still use caution and some heat.

In either case, be sure to look for and inventory all shims.... they must go back as they were... assuming that it had been done correctly before.

NOTES:

.... with the eccentric piston housing removed, you will be able to see the two "driven" gears and their teeth.

.... with the bearing box removed, you will be able to see all 3 gears and their teeth.

.... you will need to make a fixture to support and hold the transmission by it's vertical shaft.
This is nothing more than an extra spline coupler welded to a short section of 2" X 2" angle iron, and then clamped in your work bench vice.
(see image below)

.... keep in mind that the vertical shaft's top nut is a LH thread. To remove this LH thread nut, you will need the support fixture.

.... once the top nut is removed, you will be able to slide the shaft down a bit, and free up the split ring keeper.



Once you get this apart, you can better assess the gears and bearings.


A common bearing to go bad will be the main drive gear's AFT-most bearing.
If my old memory serves me, this will be an industry standard 31307 tapered roller bearing.
If you replace it, you may as well replace the smaller 30207 bearing.

See your OEM work shop manual for the rolling torque value for "NEW" bearings.


By the way, the 2 driven gear double ball angular contact bearings seldom go bad.
This is an OEM only bearing!








 

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The lower unit slinger pump pushes oil up to the transmission. Then it gravity drains through a screen and back down!

The major problem is most likely in the lower gear unit.


The oil drain back screen is at the top portion of the lower gear unit.


.
 
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The full story of this drive was the previous owner hit a log last year and his insurance paid to have the entire DP lower rebuilt to the tune of 6k bucks. My current assumption was this upper was also damaged during that event, but nobody caught it and it eventually fatigued and died on me.

My marina is going to take a look at the lower unit.
 
grubtron said:
The full story of this drive was the previous owner hit a log last year and his insurance paid to have the entire DP lower rebuilt to the tune of 6k bucks. My current assumption was this upper was also damaged during that event, but nobody caught it and it eventually fatigued and died on me.

My marina is going to take a look at the lower unit.
Click to expand...


Unfortunately, you won't find too many mechanics these days who are knowledgeable on the Volvo Penta AQ series drives.
Make sure that the person has AQ series experience, and that they know how to use heat in certain areas as to lightly expand the aluminum.
Also do not allow anyone to use a wedge between the carrier and the main gear case.

Also, when removing the prop shaft bearing carrier, and re-installing it, there is NO need for any re-shimming (as you may be told by some)!

Years ago I designed and built a prop shaft puller tool that circumvents the use of a slide hammer.
Unless someone has seen my puller tool and has made one, they will likely want to use a slide hammer.
The slide hammer puts a shock load on one of the the main bearings, and it is less effective at getting the job done.

My puller tool works on both the AQ series s/p and Duo Prop drives.
These images will show you how it used.
It is easy and inexpensive to build one.


Prop shaft carrier puller tool 4.jpg

Prop shaft carrier puller tool 5 .jpg
 

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