Transmission/Engine Issues - Kanzaki/Yanmar

[Mark_H]

That earlier thread on Throttle Lag:  http://hylasyachts.org/index.php/topic,660.msg2169.html#msg2169

And 2 years on that engine still runs like a champ.

mark h
H54 #33

[tulsag]

I was the original author of the 4JH3-DTE "Throttle lag" thread on here.  I just searched for it and it didn't come up.

In short, we tried EVERYTHING! including sending of the Bosch fuel injection pump for a rebuild.  It didn't solve the problem.  One agonizing year later I heard there were two NEW original fuel injection pumps left in the world and I bought one.  I solved the problem immediately!!  We have since sold the boat so I don't know how it has gone for the last two years.

Mark Powell
'54 Hull 33

[jtedwardsen]

Hi John,

On page 9 it looks like two versions exist a 2.45/2.45 and the 2.04/2.45. You only have the 2.04 ratio version? Everything I'm hearing from Hylas is saying 2.45 not the 2.04. Thanks for sending that manual by the way.

[SV True North]

The yanmar manual shows the 4Jh3DTE engine KMH4A transmission should be a reduction ratio of 2.04 in forward and 2.45 in reverse.  You can find the specifications on page 9 of the manual.  The manual is at https://www.yanmar.com/marine/wp-content/uploads/2020/05/Operation-Manual_4JH3DTE-49961-202851.pdf

I had a new KMH4A transmission installed in True North in 2020 and it matches the specification form the manual.

John Tyerman
True North. H54 #42

[jtedwardsen]

Hi,

Yes, fuel pump and injection pump is new because we thought the same thing. The max people is rebuilt and nothing was broken on it. The mechanic wants to haul the boat and down pitch the prop to 18degree or even 16degree to get the rpms back.

The transmission they replaced my original from the factory transmission with is now a 2.04:1 ratio which is not the same as what was in the boat but they are saying it is fine. Seems wrong to me...

[SV True North]

Jon,

I second checking the injector pump.  I had similar problems with my 4JH3DTE and rebuilding the injector pump resolved the problem.

John Tyerman
True North - H54 #42

[sjohnson]

Jon

You mentioned the fuel pump, however did you do anything with the injection pump?  We had a similar issue with RPMs several years ago with our 4JH3-DTE.  Most of the time the engine would shift into gear but would not increase rpms above idle.  However, sometimes it would increase rpms, usually after several bumps in and out of gear.  Turned out there was some corrosion in the injection pump rack/barrel area that would prevent the injection pump from increasing fuel flow.  Replaced the injection pump and all was well.

Scott Johnson
H54 - 22 Bacchus

[Knoxan]

Check an old 2017 thread "Throttle lag on Hylas 54 4JH3-DTE". Also around that time there was discussion on clutch judder.
I suffered from both for a while and then they mysteriously dissapeared in 2018. Fingers crossed.
On the judder issue I believe there was a harmonic interaction between clutch and maxprop. Completely overhauled the maxprop and problem stopped. Co-incidence???

Andy
True Brew
H46 #32

[Andrew]

Hi Jon,
i had a similar issue where there was vibration and revs would not increase after gear change - i believe there can be an issue with maxprop and cone clutch of the km4a gearbox setting up a feedback loop of clutch grab, prop opens, bounces off stop, clutch grabs again and repeats, setting off a similar cycle in the injector pump governor.  if that is the cause, you could try borrowing and fitting a fixed blade prop - I carry one as a spare) - if that solves it you could try a different type of folding or feathering prop,
hope that helps,
Andrew Eaglen,
Hylas 51

[Andrew]

Hi Jon,
can

[Matilda]

Hi Jon,
I have to agree with JT- check the injectors.
I don't have any info on your transmission but I recently had issues with my 4JH TE not developing power. Water got into one of the tanks (I think through a leaky deck fill) and this destroyed the injector nozzles. The mechanic bench tested the injectors and the spray pattern was way off. New nozzles and I'm back to the 2600 cruising rpm.

What was the reason for the original rebuild? The numbers looked good and you had no smoke.

Hoping that you get to the bottom of this issue.
Chris- SV Matilda H42

[jt11791]

As far as I know, the Kanzaki KMH4A with 2.45:1 gears was the factory original on my H54 with the 4JH3-DTE.

Your lack of power problem is puzzling, but the first place I'd look for trouble is with the injectors.  I'd pull them out and have a shop spray test them.

[jtedwardsen]

I have been dealing with engine issues after a full rebuild on my 2001 Hylas 54 #14 (Navigatio). The engine is Yanmar 125 Turbo (4JH3-DTE) with a Kanzaki (KMH4A) transmission. At this point every single item on the engine is new except for the block (transmission, turbo, fuel pumps, everything...). We have no white, blue or black exhaust at all and have not had any at any point during the rebuilds (before or after). Before I give details let me first ask a few questions to get a baseline.

1. What was the original transmission spec'ed out for the 4JH3-DTE from Hylas (yes, I have asked the factory)?
2. What should the gear ratio be for the transmission on a 4JH3-DTE from the factory?

Engine prior to rebuild was running as follows during sea trial (at slack tide):
1. 1800rpm ~7.5ktns
2. 2400rpm ~9.5ktns (cruising speed is ~2200rpm at 8ktns)
3. 3400rpm ~11ktns (Max RPM was 3400)
4. Max Prop pitch was set to 24 degrees

Engine after rebuild and was running great. Transmission was the old transmission (not yet replaced). No issues and was running as follows (at slack tide):
1. 1800rpm ~7.5ktns
2. 2400rpm ~9.5ktns (cruising speed is ~2200rpm at 8ktns)
3. 3400rpm ~11ktns (Max RPM was 3400)
4. Max Prop pitch was set to 24 degrees

After two months of running the engine, after warming up for 20 mins or so would not have any throttle if you shifted out of gear. Meaning we had full reverse or forward but after shifting into neutral and moving into another gear (either forward or reverse) we had no rpms for about 2 to 3 minutes or more then the rpms sometime would come back. At this point the mechanics replaced the fuel pump, transmission, controller, shifting and throttle cables and a second turbo (new again) after repetitive sea trials and "trial and error". Entire fuel system on the boat was bypassed using a day tank with no change.

After second rebuild was running as follows during sea trial (at slack tide):
1. 1800rpm ~6.5ktns
2. 2400rpm ~8ktns (cruising speed is ~2200rpm at 7.5ktns)
3. 2700rpm ~9.5ktns (Max RPM was 2700)
4. Transmission replaced and Max Prop pitch was set to 22 degrees (top end rpm from went from 1500 to 2700 but lost speed)

Any help would be great.

-Jon