The Walter V-drive is seawater cooled. The cast iron cooling jacket lasts about 30 years before rust destroys it from the inside. My
boat is 26 years old, so there isn't much life left in the old unit. I rebuilt it a few years ago, at which time I coated the inside of the
cooling jacket with Marine-Tex in an attempt to slow down corrosion. This appears to have worked so far, but rust had already caused
problems in the case. I also had a persistent vibration problem that I've never been able to fix. I measured run-out in the output and
shaft coupler flanges with a set of feeler gauges with the V-drive in place. This measurement is very difficult to make this way, but it
appears the output shaft on the V-drive is slightly warped. Another possible cause for vibration is flex in the engine bed or bad engine
mounts. I had the propeller sent out for service and replaced the propeller shaft, cutless bearing, and coupler, so they are unlikely to
contribute to the problem.
I don't know exactly what Pearson was thinking of when the installed the V-drive, but they definitely weren't thinking about removing
it one day. The pan is glassed to the side of the hull with some extra bracing. This makes it very difficult to access the nuts under the
v-drive pan. I can just reach the starboard side nuts, but the port side nuts are not accessible. In fact, the builder had cut one of the
mounting nuts so that it could be positioned under the pan.
In my opinion, the pan is not stiff enough. I glassed in some extra support to reduce vibration. If you've had your V-drive out in the
past for service, removal is a pretty straightforward job, but if you've never had yours out, removal can be very difficult. I suggest
soaking the mounting fasteners in penetrating oil such as PB-Blaster.
The RV-20 was heavy, but the RV-26 is even worse. Care must be taken to avoid back injury when lifting it from the pan. I used a sling
attached to the top of the case cooling barbs to make a handle. I suggest draining the oil in the V-drive before removing it unless you
enjoy wiping oil up off the garage floor.
The RV-26 uses a different splined shaft than the old RV-20. Since I had to order a new input shaft anyway, ordering it slightly longer
allowed me to move the Yanmar further back in the engine pan. Only the splined shaft had to be replaced. The remaining part of the
input shaft with universal joint was reused. A full replacement runs almost $1000, whereas just replacing the splined shaft runs $150 for
a stock 12" shaft and an extra $45 for a custom length. Removing the old spined shaft proved to be very difficult. I inserted wedges in
the jaw to free up the shaft, but no matter how I tugged on the shaft, I couldn't get it to budge. I soaked the thing in penetrating oil.
Then, I clamped the splined shaft in a vice and pounded on the jaws with a five-pound sledge. I was careful to avoid damaging the
jaws. Nothing worked. I welded a threaded rod onto the end of the shaft. Then I slid a pipe over the shaft followed by a large washer
and nut. When I tightened the nut, the shaft pulled out with no problem. This damaged the old splined shaft beyond repair, but I have
no plans to reuse it anyway.
My work with wedges on the drive shaft jaws permanently deformed the jaws, making it impossible to clamp them down sufficiently
to keep the new splined shaft from sliding in position. I ended up drilling and tapping a hole for a set-screw to hold the shaft in place.
I suggest ordering that new splined shaft after the V-drive has been mounted in position. This will allow an accurate measurement to
be taken from the engine to the V-drive neck. If you order the wrong length, you may be forced to order a second shaft. Walter will
not restock the shaft after it has been machined.
The new V-Drive is larger than the old RV-20. The mounts are much wider. Walter provides instructions for adapting the mounts to fit
an RV-20 installation, but there is insufficient clearance in the bilge of the 424 for wider mounts. The new mounts come in three
pieces, an angle bracket, a flat mounting base, and a bridge plate. I discarded the bridge plates and drilled out the stud mounting holes
on the angle brackets. I oversized these holes so that I could make adjustments for alignment and I relocated the set-screw from the
bridge plate to the angle bracket. My plan was to use the bases without the bridge plates. The base plates were too large however to
be reused. There would be no way to get nuts on the bottom of the mounting bed. I ended up fabricating new base plates from L
shaped angle iron. I made a cutout on the outside edges of the mounting bed so that I had room to insert a bolt from under the base
into the side of the pan. I welded steel nuts to the bottom of the new plates so that it would not be necessary to hold them in place. I
made cutouts in the mounting bed so that the nuts would recess into the pan. Fine thread fasteners are less prone to coming loose in
high vibration applications. The new mounting bases are bolted in from the sides of the pan. It is impossible to get a wrench on the
bolt under the V-drive flange. It would have been easier to work with these fasteners if I had welded a small piece of metal on one
side of the bolt head so that it couldn't turn when tightened. I found that medium strength lock-tight was needed on these bolts.
My impression of the new V-Drive is that it is poorly made. There is no provision to freshwater cool the unit. It runs warm to the
touch even with good water flow, so I think it definately needs cooling. Since it has an oil heat-exchanger threaded through the
cooling jacket, it will be difficult to clean. The unit comes painted a bright blue color. The paint chips off very easilly. I suspect that
the case is not properly primed before painting. The paint looks like generic Rustoeum or similar. It will require frequent retouch to