New Nanni N4.38 or Yanmar 3JH4E

[seagypsy8]

We are replacing our old diesel and would like your help in deciding between the Nanni 37.5hp or Yanmar 39hp ?
We have a 40ft fibreglass ketch liveaboard, and are interested in engine longevity/reliability and economy. We occasionally motor for long periods at 5 knots when there is no wind, and sometimes run the engine to charge our battery bank and heat water.

[Charlie]

I have a 4JH4E and love it. It has given me a little grief in the four years I have owned it but I found out that those were problems I have caused. About theonly thing I don't like about it is the dipstick. It is very difficult to get a good reading on how much oil is in the engine.

[surfmachine]

I have a nanni 3.75he, was 600hrs at 2 yrs old when I bought it in dec 2009, has stopped twice, once the mixer manifold corroded out and now the spring in the injector pump has just broken, otherwise trouble free?
Keith

[delmarrey]

Originally Posted by Charlie

I have a 4JH4E and love it. It has given me a little grief in the four years I have owned it but I found out that those were problems I have caused. About theonly thing I don't like about it is the dipstick. It is very difficult to get a good reading on how much oil is in the engine.

Charlie,
According to the manual you have to wait 10 minutes after the motor is turned off to check the oil. Also I found out when it's been sitting cold for awhile one has to pull the dipstick a little then push it back in. The rubber at the top creates a seal and doesn't allow the oil into the tube after it cools/shrinks.

I have a 3JH4E with 100 hours now. At an idle they do shake a bit but once it's up to rpm's it smooths out. Although, the install was a bitch.

Some things just have to be positioned a certain way to get it in and working. The motor mounts are a bit soft, so if your pushing a heavy boat the motor will react and the motor may vibrate more then it should. I installed a thrust bearing (Pythondrive) at the fwd end of the prop shaft and it smoothed the motor right out.

Some put in heavier motor mounts but with Yanmar's mounts one can not feel the motor running. Without the cover over the motor I can really hear the lifters clattering, so a well insulated compartments keeps the clatter down.

The motors come with their own gauges w/ or w/o idiot lights, your choice. With after market gauges one has to do some modifications.

Other then the problems I had, I do like the motor. It runs pretty good and starts at a snap. Click on my name and view some of my posts on the Yanmar.
I know nothing about the Nanni other then it's a Kubota (Korean). ..................................._/)

[rebel heart]

4JH owner; the thing is terrific.

[svcambria]

I replaced my diabolical Volvo MD21B with a Yanmar 4JH3 ten years ago. I needed to know a lot about the Volvo because it kept failing. I know next to nothing about the Yanmar because nothing (except the %#&*@ water impeller) has ever failed. 1100 hours on it now...

Michael

[Marinheiro]

Seagypsy, in some ways your choice is a bit like choosing between a Commodore & a Falcon. They both do the same job just in very slightly different ways. I went thru this decision loop a while back
First suggestion is get out your tape measure and see if they both fit. The Nanni is a 4 cyl whilst the Yanmar is 3 cyl and the Yanmar´s gearboxes are very compact, so the Nanni typically requires a little more length.
The Kubota block which the Nanni is built on is bullet proof (look under the hatch of any bobcat) and with its indirect injection will be a little quieter than Yanmar. However I preferred Yanmar for it direct injection because if your battery is a but iffy you have a better chance of getting it away.
Both use aluminium bodied Heat exchanger/exhaust manifolds and this is probably the major maintenance issue. A problem I have been advised with the Nanni´s (but not verified) is Nanni tends to change it suppliers frequently so the apparently same model may have different components from year to year.
The Nanni has a greater PTO allowance if you want to run a big alternator. Also check exhaust sizes, my 4JH4 required a 75mm exhaust which is just ridiculous for a 2.2l motor.
There have been problems with the latest 4JH4 Yanmars which have an electric fuel transfer pump, not sure if this applies to the 3JH4(search this site for discussion).
Finally if you decide on the Yanmar, forget about the standard isolation mounts - suggest install the aftermarket polyurethane mounts from Polyflex in Brisbane.
At the end of the day both are good motors, it will just be the little items that swing your decision

[noelex 77]

Originally Posted by Marinheiro

There have been problems with the latest 4JH4 Yanmars which have an electric fuel transfer pump, not sure if this applies to the 3JH4(search this site for discussion).

The starting / air leak problems that I have posted about the Yanmar 4JH4AE do not effect the 3JH4. The fuel pump is different. (If it is these problems you are referring too)
I am just about to detail my (hopefully) successful attempts to fix the problem on the 4JH4AE, but that’s better in a new post. My internet connection is too slow at the moment to post any pictures. (I am anchored behind a huge cliff, the nearest town is 10 miles from here so I am surprised there is any reception at all)

[seagypsy8]

Thank-you for your ideas & suggestions, looks like either engine would be a good choice.
Steve

[Albro359]

Any more on this thread ?

I have an old Yanmar 3QM30F which needs replacing...3JHE...well its only 38 horses, Nanni 4.50 is almost the same size...height, width, mounts and is 50 HP with a much flatter torque curve..Yanmar 3JHE drops off sharply at 1300 rpm...I have a mate that has an N4.38 and it is really quiet, efficient everything one could want and the antithesis of my 3QM cast iron spinnaker

Looks very tempting...and theprice seems not much more

Nanni users out there..tell me your experience......my Yanmar has done 10,000+ hours and only ever needed a top end overhaul ..still starts every day

[Marinheiro]

Hi Alan, does Diva still have the engine under the forard bunk with hydraulic drive? I remember having drinks aboard her in the early 80's when I was a penny less student!
The Nanni 4.50 is somewhat longer than the 3JH Yanmar, and heavier - it's a 2.2l engine vs 1.6l. If you still have that hydraulic drive and a pump with a variable swashplate then you can use that torque, otherwise for a conventional installation it is meaningless because you have to consider the propellor power curve which is very different to what the engine is capable of producing.
Theoretically 40 hp is all Diva needs to achieve hull speed, any more & you ar ejust wasting fuel. A true comparison with the Yanmar is the Nanni 4.38, the subject of the original post. If you decide you prefer the Kubota based block also consider the Beta conversions and there is also a guy in Sydney who does a good conversion
Witchards Marine - inboard diesel engine manufacturers for yacht or motor boat - WM Diesel.
per my previous comments earlier the 3JH also "suffers" from the same issue I encountered with my 4 JH - the large 75mm exhaust. Something to consider

[Albro359]

Thanks...yup that's where the engine still is with the Volvo hydraulic drive.
Yes I noted the exhaust size issue....