Yanmar 4JH issue

[j24jam]

We've got a 4JH2-DTE which is not making full revs.

It's currently maxing out around 2500RPM and it should reach, on paper, 3700RPM. (Although I have never seen the engine achieve more than 3450RPM in my ownership).

In neutral it revs to 4000RPM.

This first happened at the start of the season, and I ran the engine in neutral at WOT for a couple of mins and that solved the problem. It has now come back and this method no longer solved the problem.

So far, we have changed the two fuel filters and removed the air filter, which has made no difference.

No black smoke, so dont expect a turbo/ exhaust issue.

There is some fouling on the hull/ prop now, however not significant and given the same issue happened when it was first launched I dont think we can put this down as the cause.

What should we be checking next?

 

[westernman]

We've got a 4JH2-DTE which is not making full revs.

It's currently maxing out around 2500RPM and it should reach, on paper, 3700RPM. (Although I have never seen the engine achieve more than 3450RPM in my ownership).

In neutral it revs to 4000RPM.

This first happened at the start of the season, and I ran the engine in neutral at WOT for a couple of mins and that solved the problem. It has now come back and this method no longer solved the problem.

So far, we have changed the two fuel filters and removed the air filter, which has made no difference.

No black smoke, so dont expect a turbo/ exhaust issue.

There is some fouling on the hull/ prop now, however not significant and given the same issue happened when it was first launched I dont think we can put this down as the cause.

What should we be checking next?

From my experience the slightest fouling on the propeller will severely limit max revs and top speed.
I have the same engine and have had exactly the same experience (and same figures).

 

[j24jam]

From my experience the slightest fouling on the propeller will severely limit max revs and top speed.
I have the same engine and have had exactly the same experience (and same figures).

Thank you, I really hope thats the case. I have booked a lift for tomorrow morning so will clean up the hull and prop and retest.

If not, the engineer Ive spoken with suggests injectors go off for refurb.. @Circa £1k. So hopefully the clean bottom solves it!

 

[westernman]

Thank you, I really hope thats the case. I have booked a lift for tomorrow morning so will clean up the hull and prop and retest.

If not, the engineer Ive spoken with suggests injectors go off for refurb.. @Circa £1k. So hopefully the clean bottom solves it!

If you find that with a very clean hull and very clean prop you cannot quite make it to 3800 rpm, consider getting your propeller re-pitched.

I did mine. It was not expensive (compared to injectors) and it improved things significantly as I am somewhat under engined (85HP) for 34 tons.

 

[Irish Rover]

This first happened at the start of the season, and I ran the engine in neutral at WOT for a couple of mins and that solved the problem

I'm no engineer but would this not suggest a problem in the exhaust which was temporarily alleviated by the neutral running at high revs, but has now become more established. My previous boat had 2 x 4JH3TE engines and the manual recommended revving in neutral at the end of every use to reduce any build up of soot in the exhausts.

 

[j24jam]

I'm no engineer but would this not suggest a problem in the exhaust which was temporarily alleviated by the neutral running at high revs, but has now become more established. My previous boat had 2 x 4JH3TE engines and the manual recommended revving in neutral at the end of every use to reduce any build up of soot in the exhausts.

Perhaps, we dont get any black smoke so not expecting blocked up exhaust? (The exhaust hose was new a year ago too, so could only be in the elbow if there's restricted air flow)

 

[Irish Rover]

Perhaps, we dont get any black smoke so not expecting blocked up exhaust? (The exhaust hose was new a year ago too, so could only be in the elbow if there's restricted air flow)

I would have thought the elbow would be the most likely location of a restricted exhaust. I emphasise I'm a tech numpty so you'll definitely get more qualified opinions.

 

[volvopaul]

Thank you, I really hope thats the case. I have booked a lift for tomorrow morning so will clean up the hull and prop and retest.

If not, the engineer Ive spoken with suggests injectors go off for refurb.. @Circa £1k. So hopefully the clean bottom solves it!

4 injectors would not be a grand in the uk . If your not getting any black smoke under load you are not getting fuel to the injectors , possibly a turbo boost issue , the IHI turbos are renown for axial play in the shaft with wears out the fans as they catch the casings , have you pulled the air filter off to check ?

 

[j24jam]

4 injectors would not be a grand in the uk . If your not getting any black smoke under load you are not getting fuel to the injectors , possibly a turbo boost issue , the IHI turbos are renown for axial play in the shaft with wears out the fans as they catch the casings , have you pulled the air filter off to check ?

Good to know (would you recommend someone like PB Asher for the injectors or elsewhere if needed)?

We only pulled the air filter to see if that was restricting air flow rather than look inside the turbo.

Will try and take a look in the morning. I guess I am looking for a build up of gunk in the turbo/ signs of wear against the turbo casing?

 

[volvopaul]

Good to know (would you recommend someone like PB Asher for the injectors or elsewhere if needed)?

We only pulled the air filter to see if that was restricting air flow rather than look inside the turbo.

Will try and take a look in the morning. I guess I am looking for a build up of gunk in the turbo/ signs of wear against the turbo casing?

I use MB fuel at Eastleigh.
No build up just wear , check shaft for movement

 

[j24jam]

Sadly the lift out and bottom clean didnt have any major effect on the engine performance.
We've gone from maxing out at 2350RPM to 2600RPM.

I took the air filter off and hand a look and poke at the turbo. I couldn't move the blades with my fingers - is that correct? No movement as far as I could tell in the turn shaft.

 

[westernman]

You should easily be able to spin the blades in a turbo by hand.

 

[j24jam]

You should easily be able to spin the blades in a turbo by hand.

Ok, thats interesting... seeing if a friend can go have another go after work to save me a trip back to the boat... I may have been doing something wrong.

If they dont spin, is that turbo out for refurb or something else that may be causing it not to spin?

 

[westernman]

Ok, thats interesting... seeing if a friend can go have another go after work to save me a trip back to the boat... I may have been doing something wrong.

If they dont spin, is that turbo out for refurb or something else that may be causing it not to spin?

I don't know. Mine has always spun freely!

 

[volvopaul]

Ok, thats interesting... seeing if a friend can go have another go after work to save me a trip back to the boat... I may have been doing something wrong.

If they dont spin, is that turbo out for refurb or something else that may be causing it not to spin?

It should spin freely , if it’s seized that’s your problem

 

[j24jam]

Thanks for everyones help so far, it really is appreciated.

Sadly my friend hasn't got time, so will have to have another trip to the boat asap to work it out.

To save possible other trips, assuming the turbo does not spin freely is there anything else I should be checking while onboard?

Is it worth firing up the engine to see if it spins when running? Under load?

And if it is the turbo, can anyone recommend someone who can refurb it? (Or is it best to replace?)

 

[Dominicpriestley]

I had both my IHI Turbos re-conditioned earlier this year. Same issue, not revving above 2500rpm. Both turbos not free to spin. One locked solid. Refurb is about 50% of new cost, so budget £700 for a Recon, £1400 for new. You will need the gasket for the elbow. Order it a.s.a.p. It took me over 4 weeks to source one. These were on 4JH2-HTE engines. You will have to remove the intercooler, if fitted, to get to the turbo mounting studs. I would also recommend cleaning the heat exchanger whilst you have the turbo off, it allows access to the end cap. Again, order the O-Rings first as they were a couple of weeks lead time aswell.

 

[PeterBoater]

Thanks for everyones help so far, it really is appreciated.

Sadly my friend hasn't got time, so will have to have another trip to the boat asap to work it out.

To save possible other trips, assuming the turbo does not spin freely is there anything else I should be checking while onboard?

Is it worth firing up the engine to see if it spins when running? Under load?

And if it is the turbo, can anyone recommend someone who can refurb it? (Or is it best to replace?)

Turbo Developments - Turbo Remanufacture - Reconditioned Turbochargers - Turbo Repairs recommended.