Volvo 31P-A outdrive dilemma.

[piperca]

I'm repowering my gasoline powered boat with a pair of 31Ps (four cylinder diesels). The original drives are Volvo 280s, which I intend in changing to DP drives. I have one DP-E drive with 2.32:1 gear ratio, but I have been unable to find a second drive to match. Yes, I can probably buy a new one, but that is well out of my budget. I have decided that selling the DP-E to finance the purchase of a pair of more available drives (in the used market) would be a better idea ... what do you think?

I am not very familiar with Volvo DP drives and wondered if someone might suggest a drive that will work well with my application? I have noticed that DP-C drives appear to be more available; would this drive be stout enough for this application? Also, can someone enlighten me as to what years the model changes took place? I have a chart that shows the differences in their physical appearance, but it does not indicate when the changes appeared.

Thanks,
Andrew

 

[captmello]

Re: Volvo 31P-A outdrive dilemma.

The DP outdrives your considering are different from the 280 in these ways.

The transom shield is different as well as the cutout in the hull. The hole could be modified to fit however.

All the tilt and trim would be different even if you have power trim on your 280's.

Upgrading, IMO, to a DP, is not a practical change. Especially when you have two. With the info you've given, I would sell the dp and fix the 280s.

Why are you considering the change?

 

[piperca]

Re: Volvo 31P-A outdrive dilemma.

The 280s are in excellent condition. They have under 300 hours on them and recently were gone through and resealed. However, they don't have trim.

If I use the 280s, I'll have to cut and weld the aftercoolers on both engines, since the tilt motor is located in this area and would call for a modification. The 280s are geared at 1.61:1, which is for a V8 gasoline engine. Also, I'm led to believe the DPs are more efficient and would give better performance.

I am aware of the difference in transom shields/cut outs/etc.

Why do you suggest I stay with the 280s?

 

[Don S]

Re: Volvo 31P-A outdrive dilemma.

As long as you understand that you will be replacing the transaom shield as well as the drive, all you have to do is find 2 complete setups of the same kind of 290 DP or newer. They all have trim after the 280's, but as the models get newer, they are better in the trim system. The drives are basically the same inside, different bearings and shift cones, and changes in parts, but the same concept.
The 290DP up through the DP-C (I think) also have the lockdown mechanism. I would avoid that if possible.

 

[piperca]

Re: Volvo 31P-A outdrive dilemma.

Thanks, Don.

Yes, I am very aware of the need to replace the transom assemblies and the need to cut the opening. In fact, I believe you helped me out with a comparison chart of the different hole sizes between the Volvo drives ... thank you very much, by the way!

I was not aware of the lock down mechanism being on the 290DP. I was led to believe that the trim rams took the place of the lock down mechanism.

I have been told to steer away from the early DP drives and to look for something newer. As I said before, I have a DP-E drive/assembly that I can use; however, I'm unable to find another with the same gear ratio. I think I have sourced a couple of DP-Cs, but I wanted an opinion from those experienced in diesel sterndrives. My main concern is that they can hold the torque of the engines, without giving me future problems.

 

[Don S]

Re: Volvo 31P-A outdrive dilemma.

My main concern is that they can hold the torque of the engines, without giving me future problems.

No problem at all. They came standard on the 31 and the 41 (6 cyl) diesels.

 

[piperca]

Re: Volvo 31P-A outdrive dilemma.

Thanks, Don.