Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 29-08-2017, 06:14   #1
Registered User
 
Sandibar's Avatar

Join Date: May 2014
Location: Finland
Boat: Sandibar 35
Posts: 285
Repower - what can I do myself?

So after engine failure a few weeks ago I have removed the 30-year old 1.7L marinized Nissan. I have a decent quotation on a new Nanni Kubota four cylinder 38hp engine, but still need to make sure it fits lengthwise. The shaft has a universal joint (?) that attaches to the transmission. I think the existing exhaust fits also the new engine.
I know I will probably have to raise the engine bed stringers a bit higher by laminating. After this is done, I wonder how difficult the rest of the installation is and if I can do most, or all by myself. Am I mistaken in the belief, that I can drop the new engine on the stringers, roughly align it and then fix the engine mounts on the stringers? I would then proceed with the final alignment with the shaft by fine tuning the mount adjustments, which I assume is a bit easier because of the universal joint as opposed to a rigid flange on the shaft.
I'm not worried about controls, wire routing, hose assemblies and such, but is there some magic to the actual engine mount installation and alignment? Getting the old engine out proved to be much easier than I originally worried and maybe I'm overconfident now .
Attached Thumbnails
Click image for larger version

Name:	20170824_213120_resized.jpg
Views:	168
Size:	349.3 KB
ID:	155006  
Sandibar is offline   Reply With Quote
Old 29-08-2017, 07:07   #2
Registered User

Join Date: Jun 2017
Location: Subic Bay Philippines
Posts: 539
Re: Repower - what can I do myself?

Every thing is possible with a DIY and common knowledge but here's a few items to note

1) Dont be fooled by have a UV joint (although very un common in marine situations ) mainly seen in home made applications, with a UV joint you actually require an angle to some degree to make the bearings work other wise if in direct alignment they can "chatter" and prematurely wear out(same thing on cars and trucks why you always see an angle,
2) Pay attention to the Riser height and the water trap (lower) height (if raw water cooled and on or below the water line
3) If gear box ratios have been changed the propeller will need to be re sized/re-pitched also need to consider what RPM is the new to old engine

Installation should look like the below
Attached Thumbnails
Click image for larger version

Name:	tYPICAL UNDERWATER SET UP.jpg
Views:	197
Size:	7.5 KB
ID:	155013   Click image for larger version

Name:	Typical Above Water line.jpg
Views:	220
Size:	8.9 KB
ID:	155014  

Captsteve53 is offline   Reply With Quote
Old 29-08-2017, 07:11   #3
Registered User

Join Date: Jun 2017
Location: Subic Bay Philippines
Posts: 539
Re: Repower - what can I do myself?

Just a quick note: it would be good to see a picture of this UV joint and how that system is hooked up due to my notation on the first point, just like to be sure we are talking Apples and Apples

Cheers Steve
Captsteve53 is offline   Reply With Quote
Old 29-08-2017, 07:16   #4
Registered User

Join Date: Jun 2017
Location: Subic Bay Philippines
Posts: 539
Re: Repower - what can I do myself?

Sorry, forgot to say your theory about the installation is fairly good (sight un seen!)

Just be sure your exhaust diameters are correct-dont go adapting to a smaller size (as it's close or easier) what ever your exhaust diameter is out of the new engine must be followed (can be larger-just not smaller diameter)

Cheers Steve
Captsteve53 is offline   Reply With Quote
Old 29-08-2017, 07:27   #5
Registered User

Join Date: Apr 2013
Posts: 931
Re: Repower - what can I do myself?

You can also lean on vendors to help you. I found Betamarine has excellent phone support and Kubota spare parts are available everywhere.

http://betamarine.co.uk
SecondBase is offline   Reply With Quote
Old 29-08-2017, 08:05   #6
Registered User
 
Sandibar's Avatar

Join Date: May 2014
Location: Finland
Boat: Sandibar 35
Posts: 285
Re: Repower - what can I do myself?

Thanks for the pointers! Captsteve, I'll take pictures of the UV joint tomorrow, when I get back to the boat. I have nothing against using a pro to do the critical parts of the installation, but will try to do most of the prep work myself.
Sandibar is offline   Reply With Quote
Old 29-08-2017, 10:21   #7
Registered User
 
GrowleyMonster's Avatar

Join Date: Dec 2012
Location: New Orleans
Boat: Bruce Roberts 44 Ofshore
Posts: 2,842
Re: Repower - what can I do myself?

What they said. Think it out carefully, measure, compare. Lots of folks do this. Beta even encourages owner installation of their marinized Kubotas.

Just getting the new engine down on the stringers and being able to rough align it and study it a couple of days is a plus, even if you have a mechanic come in on it. Think about the maintenance you will have to do such as changing impellor, filters, oil check and change, etc and make sure you will have reasonable access. Figure out where ancillary systems like primary fuel filters, electric fuel lift pump, etc will go. Any wiring or cable connections. Are your shift and throttle cables going to work as installed? Just knowing everything will fit before you get a pro down there billing you by the hour and with a minimum, might save you a lot of beer money.

By universal joint I assume you mean the steel kind with a cross looking doodad in the middle and yokes for input and output riding on it with bearings? Or is it a flex coupling with a rubber or composition "spider" between two notched flanges? Or a splined shaft in a coupling with internal splines like a tractor PTO? You may still have alignment issues. I would have a mechanic check out your work, if possible. Particularly shaft alignment, torque on motor mounts, etc.

Oh, are the rated power and RPM similar between old and new engines? Since you are keeping the same prop and transmission, having similar engine output specs will make things pretty simple and give you similar efficiency and power with the new engine without changing anything. If the prop is too big for the new motor you can usually take it to a shop and have them cut it down a bit.
__________________
GrowleyMonster
1979 Bruce Roberts Offshore 44, BRUTE FORCE
GrowleyMonster is offline   Reply With Quote
Old 01-09-2017, 03:59   #8
Registered User
 
Sandibar's Avatar

Join Date: May 2014
Location: Finland
Boat: Sandibar 35
Posts: 285
Re: Repower - what can I do myself?

I made a mock up of the Nanni Kubota engine and it seems that because the oil pan is so deep, installation will be difficult. Mitsubishi based engines seem a better fit. Currently looking at Craftsman 4-cyl. 1,7l 42hp, or comparable Vetus. Will check today if they fit, but at least they sit lower than the Kubotas.
Here are a couple of pics of the shaft and joint. I think I'll change the stuffing box, or at least the internals while I'm at it. Is there some secret to removing the flange from the shaft end?
Attached Thumbnails
Click image for larger version

Name:	20170830_184648_resized.jpg
Views:	190
Size:	424.1 KB
ID:	155193   Click image for larger version

Name:	20170830_192036_resized.jpg
Views:	176
Size:	425.5 KB
ID:	155194  

Sandibar is offline   Reply With Quote
Old 01-09-2017, 05:19   #9
Registered User

Join Date: Jun 2017
Location: Subic Bay Philippines
Posts: 539
Re: Repower - what can I do myself?

Quote:
Originally Posted by Sandibar View Post
I made a mock up of the Nanni Kubota engine and it seems that because the oil pan is so deep, installation will be difficult. Mitsubishi based engines seem a better fit. Currently looking at Craftsman 4-cyl. 1,7l 42hp, or comparable Vetus. Will check today if they fit, but at least they sit lower than the Kubotas.
Here are a couple of pics of the shaft and joint. I think I'll change the stuffing box, or at least the internals while I'm at it. Is there some secret to removing the flange from the shaft end?
OK, Thats what i meant by Apples and Apples your "universal joint" looks like it's a CV JOINT (which is better!)

The Constant velocity (CV) joints allow the shaft to connect the engine and the main propeller shaft at an angle. The rolling action of the balls within in the CV joints absorbs all axial and radial loads.Normally they can take up to approximately 12 to 15 degree's of miss-alignment if needed but you should still try to get as close as possible where possible

Requires a Thrust bearing
The thrust bearing is mounted directly into a structural member in the hull allowing the propeller to push the boat and not the engine.

Universal joints still need certain types of alignment other wise they work correctly and varying speeds can result causing all sorts of issues, where as your CV joint will truly take up miss-alignment and fitment of soft flexible mounts as the thrust bearing takes the load from the Propeller.

Just check there's no "yoke" universal joint under that rubber boot to be 100% sure it's a CV joint!you dont need to take apart just squeeze the rubber boot!

Cheers Steve
Captsteve53 is offline   Reply With Quote
Old 01-09-2017, 08:27   #10
Registered User
 
Sandibar's Avatar

Join Date: May 2014
Location: Finland
Boat: Sandibar 35
Posts: 285
Re: Repower - what can I do myself?

I removed the rubber and it does not look like a yoke to me. The forward joint moves horizontally for about an inch back and forth, hope this is normal. I assume the thrust bearing is inside the green plate that the shaft goes through? Is there some special way to remove and reinstall the shaft through the bearing? Thanks to everyone for the advice so far!!
Seems I need to raise the stringers by some 10 cm (4") to have the engine horizontal and roughly aligned with the shaft. Planning to laminate and glass in two 2x4s on top.
Sandibar is offline   Reply With Quote
Old 01-09-2017, 08:54   #11
Registered User

Join Date: Jun 2017
Location: Subic Bay Philippines
Posts: 539
Re: Repower - what can I do myself?

You just need to remove the four bolts, undo the locking bolt on the flange hub, from there depending on how long its been on the shaft you may need a puller to remove the flange/hub from the shaft (or even a little heat) some times they will come of with a little persuasion from a hammer but be careful not to damage the coupling (there could also be a larger nut inside on the end of the shaft after you separate the coupling,

There should be also some lock screws or similar stopping the shaft from going through the bearing or perhaps the shaft is larger diameter at that point which absorbs the propeller thrust,

Cheers Steve
Captsteve53 is offline   Reply With Quote
Old 01-09-2017, 08:58   #12
Registered User

Join Date: Jun 2017
Location: Subic Bay Philippines
Posts: 539
Re: Repower - what can I do myself?

Forgot to say, you could consider just raising the engine bed in the four places that the mounts will sit as that will give you more access to engine/gear box parts etc, with that CV system there should be no longitudinal load/pressure on the engine bearers at all

Cheers Steve
Captsteve53 is offline   Reply With Quote
Old 14-09-2017, 06:57   #13
Registered User
 
Sandibar's Avatar

Join Date: May 2014
Location: Finland
Boat: Sandibar 35
Posts: 285
Re: Repower - what can I do myself?

Just an update if anyone's interested. I have raised the engine bed stringers now by 10 cm (4") by laminating and glassing in two 2x4s. I will go with a Beta 35hp/1,5l engine, which fits nicely. Beta has the option for a lower oil pan, which was the final selling point. Price was also really good.
Since the engine is now out I would like to change the cutlass bearing and the thrust bearing, as well as the shaft seal. I think I can do this without dropping the rudder: move shaft back by 40cm to change thrust bearing and shaft seal and after removing the prop, push the shaft forward to change the cutlass bearing.
Do the bearings get old? I think the boat gets max 100 engine hours per year, but I have no clue if and when they have been changed. The boat's from 1988, but the shaft turns easily by hand and there is no play. I'm more worried about the seal myself.
Sandibar is offline   Reply With Quote
Old 14-09-2017, 08:00   #14
Registered User
 
UNCIVILIZED's Avatar

Join Date: Jun 2014
Location: Up the mast, looking for clean wind.
Boat: Currently Shopping, & Heavily in LUST!
Posts: 5,629
Re: Repower - what can I do myself?

I know that it's kinda' late for this to be of help for the OP, but... Nigel Calder has written a few magazine articles on doing repowers, including on his own boat. This one touches on it briefly, but there's another one or two in which he goes into the full details of things.
A Refit Reality Check | Cruising World
__________________

The Uncommon Thing, The Hard Thing, The Important Thing (in Life): Making Promises to Yourself, And Keeping Them.
UNCIVILIZED is offline   Reply With Quote
Old 27-09-2017, 09:30   #15
Registered User

Join Date: Dec 2009
Location: aboard Akka, currently in San Francisco Bay
Boat: Stevens Custom 50
Posts: 77
Re: Repower - what can I do myself?

Sandibar, for what it's worth, the thrust bearing/CV setup is much better than the standard straight shaft, for a number of reasons. First, obviously, is the lack of need for precise alignment, which not only makes for easier installation but provides some security -- we broke an engine mount and when the engine "fell", it surely would have bent the shaft were it not for the CV. But another overlooked feature of thrust bearings is that the propeller drives the boat, not the engine. This means less wear and tear on the whole system; it also makes it easy to pull the propeller shaft.

The one problem with a thrust bearing is that the prop shaft can come out of the bearing if the set screws loosen. Put a hose clamp around the shaft anywhere between the thrust bearing and the hull seal, so if it comes undone it won't simply fall out (or slam back against the rudder).

As for replacing the cutlass bearings, my thought is, if it ain't broke, don't fix it. The state of a cutlass bearing is easily determined: grab the shaft with both hands right near the bearing, and try to wiggle it laterally. If there's any play, replace the bearing. If not, the bearing is good. With less than 100 hours a year, it's probably still good.

On the other hand, if you're using an old-fashioned stuffing box, consider replacing it with a dripless seal.
Akka is offline   Reply With Quote
Reply

Tags
repower

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
repower quandry You can help. capnmoe Monohull Sailboats 13 22-07-2017 17:16
Allow myself to introduce myself mayday51 Meets & Greets 4 12-01-2016 17:38
repower or two repower Immanuel General Sailing Forum 4 07-05-2012 09:24
Solar MC4 Connectors - Can I Do Myself ? arjand Electrical: Batteries, Generators & Solar 11 14-02-2012 10:09
Kicking myself, but glad I can. Alan Wheeler The Sailor's Confessional 51 18-04-2007 23:16

Advertise Here


All times are GMT -7. The time now is 07:12.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.