Transmission Replacement: What I learned (long)

[Bill Shreeves]

Rock & Roll!

Or, replace it with a Twin Disc TMC-40 as I am and it is only 4mm (>3/16") longer and 1/4 of the price of a ZF10 ($1259 vs. $5000 on CD).  I'm mid project right now, having removed the exhaust riser and heat exchanger, drained coolant form the motor, and removed the alternator and wiring from the motor.

I'll report back when I've successfully swapped the gearbox and relocated the heat exchanger.

Patches

[Stu Jackson]

Ron, If I recall it was an 1" longer.  Do you really think that would make that much of a difference?

Bill,

Yes, because of the clearance required between the prop and the rudder.

[Noah]

As well as (possibly) violating the "rule" that the prop should be no farther than 1in. behind the strut.

[Ron Hill]

Guys : I agree with Noah " rule of thumb - the prop should be one shaft diameter behind the strut".

A thought

[Patches]

Well...change of plans.

The decision to go with a new transmission was based on the assumption that the motor was good to go for another few seasons (at least).  I take extremely good care of my motor, and have added much new while its been on my watch.  It ran super reliably, didn't smoke, and--until recently--didn't leak any oil.  It has approximately 2500 hours since new in 1990.  Even so, the new leaking was toward the back of the engine, relatively minor, and the oil level never got to the level where I was adding new oil between changes (roughly every 65-75 hours).

So, I'd purchased a bunch of things in preparation for the tranny swap:  new motor mounts, hanger bolts and nuts to secure them, and damper plate.  I also fabricated a new mount for the heat exchanger out of 1/4" aluminum angle stock to hang from the underside of the rear berth, and purchased the new hoses to make the extra run from the engine.

We pulled the engine on Wednesday to replace the transmission and placed it on the galley floor.  We'd prepared the area with some plywood and drop cloths.  After removing the bell housing, we saw some oil on the inside suggesting the need for a new rear seal. No biggie.  But my mechanic, a very experienced guy, showed me how there was "end play" in the main shaft which would require a much more significant rebuild to remedy.  In his view, putting in a new seal would be--at best-- temporary and the leaking would be back within a matter of time.

So, time to choose.  I could do "half a re-power (transmission only and assorted shorter term fixes like the rear real)", get through the upcoming charter season, and decide to re-power a year from now.  Or, I could do a "full re-power" and pull the engine only once, start the charter season a little later, and be done with it.

Like many others facing this choice, I thought about rebuilding to get several more years out of the (otherwise) super reliable motor.  I LOVE that motor for its ease of maintenance and reliability.  But, it is 32 years young now and I'll be keeping the boat for a while as part of the business.  I'd already decided that in the event of a re-power it would be a new Beta 25, to the exclusion of the M25 XPB or a 3 cylinder Yanmar.

So, I ordered a new Beta 25 which I'm told will be shipped in "March."  I hope so.  In the meantime I'll be able to make many of the preparations in the engine bay pending its arrival. 

I'll also be selling a couple of the items I recently purchased for the original M25xp, like the Compass Marine 105 amp small frame alternator which I added as part of my electrical upgrade 2 years ago, as well as some spares.  So, check the "parts and pieces" classified if you need something for your M25xp.  I don't think I'm going to part it out, preferring to sell it as a complete motor with the original alternator.

Patches

[Pdbwraz]

My transmission just failed which resulted in a 50 mile tow through Kent and knapps narrows in some rough weather/waves action. How is the project going?  Any additional advice or suggestions as I begin the process?  Very nice and detailed write up.

Thanks
Paul

[Ron Hill]

Paul : You have a 37 year old engine and (as happened with me ) you could be facing oil seal failure/s.  I'd advise that you just get a new engine w/transmission so you can get away from the dock and do some sailing!!  I wound up pulling and fixing my old (5000 hrs) engine 2 times and the third time I said - ENOUGH!!  I just got tired of playing mechanic rather than being a sailor!!!  Treat Yourself !!   thumb:

I went with the M25XPB where I could use the same wiring connections, same throttle /gear shifter connections and the same Catalina engine instrument panel.

A few thoughts 

[Pdbwraz]

Thanks for the advice.  Definitely considering that route as well.

[Pdbwraz]

Ron -I see you are in the Chesapeake area, where did you get your new one?

[Patches]

Wish I could tell you I am finally finished with my Beta 25 install, but can't--just yet.

The Beta 25 has a manual fuel pump on the engine which--in theory-- is very simple to operate in order to deliver fuel from the tank to the engine, and then to bleed the system. Both my mechanic and dealer said you can take out the old electric fuel pump as it wasn't needed.  So I did to create a little more room under the head sink for a new Racor 500fg separator, and moved the new strainer to the back side of the head bulkhead under the shower sump switch.  I then cut in a 6" X 6" access door (just below the switch and above the shower seat) that allows me to check the strainer and clean it very easily.

After sorting out the external regulation, electrical and cooling connections, I set about trying to bleed the engine with the "manual" pump on the engine.  Wasn't pulling fuel up through the bleed screw on top of the primary fuel filter on the engine.  Checked for air entry everywhere.  At one point, I thought I had it isolated to between the new Racor and the tank.  I pulled the pick-up tube from the tank-- both tube and shut off valve were clear.  Pulled the vent tube and vent, both clear.

I then did what I  should have done initially.  I took a short length of clear hose from the inlet side of the manual fuel pump to a Jerry can with diesel.  Operating the "thumb" lever on the fuel pump, I confirmed nothing was getting pulled from the Jerry can:  Bad manual fuel pump.

So I'm re-fitting the old electric fuel pump to the system and have a warranty claim on the OEM manual fuel pump.  Not what you want with a brand new engine.  Hopefully will get it started up today.

I have to say, Joe Demers at Sound Marine Diesel has been terrific to work with.  He picks up the phone, and cheerfully answers my many questions about the engine and installation.  Another person from Beta carefully walked me through the external regulation set-up on the Iskra 120 Amp alternator.

Again, I'm hoping to do a more comprehensive write-up once I'm done with Sea Trials.

Patches

[boatnut]

Hi Patches,

Just reading your awesomeness write up. I'm also in that grey area of rebuild or replace a 37yr motor. It's got oil leaks everywhere. Doesn't burn, pushes the boat nicely at 5kts.

I'm shopping for the Beta 25 as well. Seeing how your install and final sea trial went? Where you able to make 5kts or higher?

Thanks,
Bostnut
(Scott)

[Stu Jackson]

I'm very conflicted about the discussion about the "need" for anything larger than a Beta 25 in a Catalina 34.

I have a 1986 boat with a measly little puny incompetent undersized useless M25 engine, with 21 HP.  In 1987 Catalina started putting in the bigger M25XP which is essentially the same engine with the alternator bracket upgrade and a 3 inch HX and all of 23HP.  Soon after I got my boat I fixed the bracket and put in a 3 inch HX.

From 1998 to 2016 I sailed San Francisco Bay with its currents, in and out the Golden Gate regularly, out in the ocean all they way down to Monterey, and the California Delta.

In 2016, we headed out The Gate and turned right to Canada.  It took 6 weeks and 1,650 nm later landed in our new home at Maple Bay on Vancouver Island.  I have been cruising here since.

At NO time have I ever felt the need for more power, because after 2750 rpm the boat squats and doesn't go much faster.

In 1994 Catalina started putting in 30 HP engines.  I have cruised with many Mark II boats and when we're motoring they do go a tad faster, but just a tad.  Heck, I could've been running at 2750 rpm and they could have been at WOT but there is certainly not enough, in my mind, to warrant a larger engine than a Beta 25 if it is rated for 25 HP.

[Ron Hill]

Guys : The "rule of thumb" for the distance of the front of the prop to the rear of the strut is 1 shaft diameter (or 1 inch).

Not too sure about 2 inch distance?? and wear on the cutlass bearing from the extra inch and gyroscopic precession??

A thought

[waughoo]

Stu,

I also agree.  I honestly appreciate my m35 that has 4 cylinders as I feel it is a bit smoother when running.

The down side however is the fuel consumption.  Here in the PNW, there is a LOT of motoring (see Logo Freak's re-tank on his boat to increase fuel capacity). Using more fuel for little gain in performance seems a luxury not supported by the fuel capacity of the stock set up.

[Ron Hill]

Paul : I got my new M25XPB engine from the Universal Dealer in Norfolk.

I see you are on the eastern Shore - If you or a buddy has a truck you can pick up the engine your self and save the transportation $$ cost!!

A thought