Keep Kubota 35 or repower with Perkins 50 for a 1969 Morgan 38 (16000 lb)

[caveman_b]

I had my ZF10 transmission fail last year and I'm finally getting around to doing something about it. The transmission was paired with a Kubota 35 that was marinized by Phasor. I had previously spent ~$2500 getting a Witchard/WM Diesel heat exchanger to replace the very corroded one that was with the engine when I bought the boat. The ZF10 needs seals (fluid leaking/pouring out) replaced and likely needs rebuild (no idea how old/hours).

I had talked to Joe DeMers of Sound Marine Diesel a while back and he suggested pairing the Kubota with a TMC 60. That would run me about $1800.00 USD + odds and ends. The Kubota ran great when I took her out although there were some small coolant leaks from front face (needs seals that I already have parts for), and it needs to be refinished/painted.

I also have an opportunity to pick up the Perkins 50 HP (rebuilt) with Velvet Drive trans (and misc including engine mounts) for $2500 that was in this same boat prior to the Kubota. The boat is already set up for this motor, I would need to remove the adapter plates put in for the Kubota and the holes should line up (per prior owner that has the Perkins).

Perkins is 450 lb vs Kubota 250 lb. V Drive is heavy, 153 lb vs TMC 60 (recommended for the Kubota) at 33 lb. That is a 300 lb difference. Could maybe match the Perkins with the TMC and that runs 483 lb.

If I stay with Kubota, I'm only out $1800.00 + misc for the new TMC 60 trans. If I go with Perkins I have motor and trans for $2500.00, unless I want the mech trans (which adds $1800.00 + to that, of course).

The Kubota pushed the Morgan in fair weather and seas (and for a bit in semi-rough bay conditions against 25-30 kt headwind) just fine, but I had little experience with it before the transmission gave out.

With the Perkins I could see that I might be able to add a second alternator or higher power alternator without sacrificing too much, depending on space (engine room is kind of tight already). It's also a VERY good deal with transmission and extras for $2500 USD. The owner builds performance motors so I expect the rebuild was done well. With the Kubota I am saving weight. I have some experience with Kubota (tractor engine, restarting a friends old boat that sat for years) and they seem very reliable.

Thoughts?

[Cheechako]

Well, it's hard to beat a Perkins 4-108 (I assume that's what it is) But there's always risk in an unknown rebuilt engine also. What do you know about that engine really? "How" rebuilt is it? Does the seller have receipts for the work or parts?

Also in play is your confidence in the Kubota, I assume it's an older engine and you mention some things it needs.

If confident in that engine, I would probably lean to keeping it, although I love Perkins engines.

[skipperpete]

Its a fairly big leap between the vee drive and the ZF10, thats a totally different geometry. The seals in the ZF arent all that hard to do but there might be other problems that caused the seals to leak, like a bad alignment or a collapsing driveplate.

[Searles]

If the Perkins 50 is a 4 108 ,it’s actually about 40 @3000 rpm continuous ,a verry good long life engine ,with minimal service requirements.⛵️⚓️

[Bellinghamster]

I'm a big fan of Velvet Drives - they're bulletproof. I've had a bunch (9?) of them in different boats (ranging from 54-300hp, diesel and gas, slow speed and high), although never had a V-drive. Most were 20-40 years old. I've currently got one behind my 75hp Yanmar (that replaced a Perkins 4-154) in my 1978 sailboat and one behind my ~240hp Ford 351 Windsor in my 1977 Mastercraft comp. ski boat. I put new seals and clutch plates in both of those and the one had behind a Perkins 4-236 (85hp) that replaced the 4-156 in my previous sailboat. Clutches weren't needed, really only needed output shaft seals, but once I was into it why not replace all seals and the clutch plates - they come with the rebuild kits). Did nothing to any of the others other than change and check the oil. If you keep water out of it and change oil every once in awhile it it should outlast you, but it IS kind of overkill for a 50hp engine and definitely so for 35hp. Penalty is weight and size, plus efficiency hit spinning the hydraulic pump and larger gears.

I like hydraulically clutched shifting - you can't really hurt them unlike some cone clutched boxes that'll grenade if you shift from F-R or back too quickly, or eat them selves if you sail in neutral, or jam the clutch if you sail with it locked in the wrong direction.

I'd steer clear of any transmission weighting less than 75lbs unless you're a race boat.

[Mickeyrouse]

I think you’ve answered your question- give the Kubota-Hurt the attention it needs and stick with it.

[NorthCoastJoe]

Stay with Kubota, Perkins is a dirty old dog that I myself have learned to hate.
I have a TMC 60 on my Beta 50 and have had no problems.

My ole Perkins belonged in a display case of yesteryear engines, not in a boat.
Why would you go with a much older engineered engine, unless you like working on them.

And I know there are plenty of people who love Perkins, I have one in a backhoe and it is a leaky dirty dog too. So I still own one until it dies.