Yanmar 4JH3-HTE down on power - revs slowly drop off

[Sam McD]

Yeah the motor does have an intercooler. That's already on my list to check. I did check all the intake hoses and all clamps are tight and nothings obviously leaking. The turbo doesn't even seem to be trying to make boost. I can get my hand awfully close to the intake before feeling any amount of wind, so the motors just not drawing in the amount of air I would expect it to.

The one thing that's been playing on my mind is the lack of black smoke at wide open throttle.

If the turbo was shot, but the motor was still trying to add the fuel it thinks it needs to get the revs up, wouldn't the motor start puffing black smoke from the overly rich mix?

A lack of enough fuel still sounds plausible, because the exhaust color doesn't change when the revs stop climbing.

If there was an intake or exhaust blockage stopping the motor from breathing, would I still expect to see black smoke as the fuel was dumped in, or would the lack of RPM brought on by the lack of ability for the motor to breath also prevent the fuel pump from supplying too much fuel?

hmmmmm.

[Mike Banks]

White smoke is un-burned diesel or leaked hydraulic oil from a faulty vacuum modulator valve, if you have a hydraulic transmission and it is fitted with one.

Yanmar engines LIKE to rev all day and night. Mine is happy at any range OVER 2500 and it likes to go even faster, very sweet about 3000 when most engines are out of breath.

That may be part your problem--that propeller pitch may be wrong, but that would not make your power drop off, just prevent you from ever developing it. It sure would explain the white initial smoke though, usually a sticking injector.

You might try some injector cleaner in a small batch of fuel in a jerry can.

If there is a prop expert in your neck of the woods, see if you are over-propped you can sometimes get the pitch reduced a tad to make it spin more easily. They heat them then press them--it works a treat most times. If the engine and transmission has been changed at some point, that would explain a mis-matched propeller. Some engines had a variety of gearbox ratios and props to match them for the hull speeds.

[Sam McD]

Originally Posted by Mike Banks

White smoke is un-burned diesel or leaked hydraulic oil from a faulty vacuum modulator valve, if you have a hydraulic transmission and it is fitted with one.

Yanmar engines LIKE to rev all day and night. Mine is happy at any range OVER 2500 and it likes to go even faster, very sweet about 3000 when most engines are out of breath.

That may be part your problem--that propeller pitch may be wrong, but that would not make your power drop off, just prevent you from ever developing it. It sure would explain the white initial smoke though, usually a sticking injector.

You might try some injector cleaner in a small batch of fuel in a jerry can.

If there is a prop expert in your neck of the woods, see if you are over-propped you can sometimes get the pitch reduced a tad to make it spin more easily. They heat them then press them--it works a treat most times. If the engine and transmission has been changed at some point, that would explain a mis-matched propeller. Some engines had a variety of gearbox ratios and props to match them for the hull speeds.

Hey Mike,

The boat has a Max prop and we just quick slipped the boat to reduce the pitch from 22 degrees which it was at, to 18 degrees which is what the Max Prop manufacturer recomended for our boat/engine/gearbox/prop combo. The change in pitch made little difference really. But like in my first post, straight after we re-pitched it, the motor did make about 3000RPM for about a minute or two, before falling back to around 2500RPM and never making it past that again.

[kenbo]

Sam,

I don't have anything new to add to the discussion but your high boost turbo engine was severely over propped for an undetermined period of time. Lugging a NA diesel is bad, lugging a high boost turbo is worse. You already have blowby on an engine with only 2500 hours.

I'd focus on the items that wear the most when exposed to very high exhaust gas temperatures and extreme combustion pressures. As Mike said, the white smoke at startup means unburnt fuel. Your injectors need service and your turbo needs a check as well. The PO didn't do that engine any favors in his false economy prop pitching.

[Mike Banks]

Ok--I think you need to check your governor settings. Check the sleeve and the spring if it is a mechanical type, clean and lubricate. I am not sure what kind your engine has but if it is an electronic one, check all connections. The no-load engine speed settings would be about minimum 850 revs plus or minus 25, the high speed about 3850 plus or minus 25'.

[hpeer]

4JH4TE.

Long story short.
I had some sludge get stirred up in the tank.
There after the engine would max out at 1,600 RPM. FWD, NEUTRAL, or REV.
Eventually sent fuel pump for service. Report came back fuel oikp was fine but dirty.
I am assuming the sludge gunked up the governor.

BOTTOM LINE….
Does this problem remain while in Neutral???
If not, then ignore this post.
If it does have the pump serviced.
BUT make sure to carefully mark the gear alignment before removing. There is an idler gear and regaining timing can be interesting.

[Sam McD]

Originally Posted by kenbo

Sam,

I don't have anything new to add to the discussion but your high boost turbo engine was severely over propped for an undetermined period of time. Lugging a NA diesel is bad, lugging a high boost turbo is worse. You already have blowby on an engine with only 2500 hours.

I'd focus on the items that wear the most when exposed to very high exhaust gas temperatures and extreme combustion pressures. As Mike said, the white smoke at startup means unburnt fuel. Your injectors need service and your turbo needs a check as well. The PO didn't do that engine any favors in his false economy prop pitching.

Yeah - you gotta love it when other people do stupid things and it becomes your problem.

I'm going to endoscope the exhaust pipe/muffler to rule out a restriction. The fact that the motor doesn't seem to be drinking air like most diesels and the pressure coming out the breather (dont get me wrong, its not a hell of a lot of pressure, but theres definitely positive crank case pressure there) could point to a restricted exhaust.

Originally Posted by Mike Banks

Ok--I think you need to check your governor settings. Check the sleeve and the spring if it is a mechanical type, clean and lubricate. I am not sure what kind your engine has but if it is an electronic one, check all connections. The no-load engine speed settings would be about minimum 850 revs plus or minus 25, the high speed about 3850 plus or minus 25'.

I will double check the governor stops when I'm down tomorrow. Its a mechanical control leaver so fairly basic. Moves smooth and hits its current stops no problem. The motor definitely revs out over 3500 in neutral so I don't think the stops will be the cause, but will confirm what its high speed, no load RPM is.

Originally Posted by hpeer

4JH4TE.

Long story short.
I had some sludge get stirred up in the tank.
There after the engine would max out at 1,600 RPM. FWD, NEUTRAL, or REV.
Eventually sent fuel pump for service. Report came back fuel oikp was fine but dirty.
I am assuming the sludge gunked up the governor.

BOTTOM LINE….
Does this problem remain while in Neutral???
If not, then ignore this post.
If it does have the pump serviced.
BUT make sure to carefully mark the gear alignment before removing. There is an idler gear and regaining timing can be interesting.

No issue reving to its expected RPM max in neutral. Just wont make expected RPM while moving the boat.

[Oldwheels]

Seems you have done the easy and somewhat difficult.
Are you spitting water normally?
Is engine temp in normal range?

A. Pin holes in the exhaust elbow will return quickly. I replace mine with a cast version aftermarket, Find it in google. A soup of salt water and hot exhaust gases make a nasty brew. The Yanmar was junk and continued to be used.
B. Turbo not spinning up. You should hear the whine. Possible exhaust blockage, excessive back pressure. It will also run very hot. Check hoses, muffler, etc. I have seen hoses collaspe on the inside. Can you spin it easily by finger touch?
C. Run the correct pitch. Your engine will max efficiency about 32-3300 RPM. After that horsepower gain is not entirely significant but fuel consumption will go up.
D. Check all fuel line on engine. Tighten clamps, etc.

Hope this helps. I am in Savannah , Ga. If nearby I can help. I have installed diesel engines all my working days.

[blondjohn]

Hi Sam McD,

From your last post it sounds like you have a mechanical governor. Is that correct? Do you have a cold start pull cable / knob on the engine coming from the governor? Try pulling t all the way out and make sure it stays all the way pulled out. Run the engine in gear and if the cold start (over-riding the governor) fixes the rpm problem under load, the root cause of your problem is with the governor. Please try this easy test to determine if the governor is the problem. When our Yanmar governor started failing it delivered enough fuel to start the engine instantly and run the engine at full rpm in neutral but not enough fuel to run at full rpm in gear. Sound familiar?

[more]

This is now time to call Yanmar service or go on the Yanmar engine forum.
But if i be on your place you check everything
/ 1 install temporary electric diesel fuel pump 1-3 bar (check repair manual for your engine)
if don't solve the situation call somebody with experience with this engine minimum 5 years of working to Yanmar.
This people have resource, go every year in some seminar, always can send email in japan.
i think is time to give up and call the specialist.

for example high pressure pump i never open. i remove from engine and send specialist.
injector remove send specialist for check.
repair or i prefer buy new

[jimbunyard]

2500 hrs at 4 inches overpropped?

I'd be doing a compression test while the injectors were being serviced...

[more]

[QUOTE=Kenomac;1196182]I've been waiting to post this one on it's own thread:

The best 450 Euros I’ve ever spent

Carmeron,

It's a miracle! Our Yanmar 4JH3-HTE revving problem is solved, and you won't believe the cause. You might want to check your prop.... really?

Following months and lots of Euros spent, we replaced our deceased turbo with a brand new unit a week ago, certain that the burned out, rusty, no pressure turbo with missing fan blades was causing our low revving problems. Over the past seven months we could only rev the 900 hour Yanmar to 1400 rpms giving us 30hp instead of the promised 100hp. Excited.. We tested the new turbo on a sea trial..... results: Same problem, only now I was 4,000 Euros poorer.... and damn…. Now we had thick black smoke coming from the exhaust whenever the engine was under load. As if things couldn’t get worse… a new, or rather returning issue had re-surfaced which the UK surveyor had diagnosed as a transmission problem, so while I was making plans to have the engine management system fuel pump shipped to Barcelona, I decided to have the boat hauled out to check the Max prop which I thought was the occasional source of a banging noise when the transmission was shifted from forward to reverse. I did this so that I would feel secure while "putting around" the island at 5 knots on a 54ft yacht... After all… I didn’t want the “just serviced” prop to fall off.

In desperation, we contacted the "best" local mechanic money can buy in Mahon, Menorca, (Santi form Nautic Center) who came over to listen to the banging prop. After revving the engine a few times in gear at the pontoon.... he diagnosed the issue to be the prop propeller pitch. Really? So earlier today I hauled out onto a lifting sling for 450 Euros (which included the mechanic and an assistant for three hours) while the expert and his assistant took apart the prop (the same prop an expensive UK knucklehead mechanic had serviced 8 months earlier). At this point, I was willing to try anything before spending another 4,000 Euros on a new fuel pump injector system.

The mechanic asked me a few questions regarding what I knew of boat speed at various rpm’s, I wrote 7 knots @ 2,000-2,200, 6 knots @ 1800-2000, & 5-5.5 knots @ 1400 rpm... That's all I wrote down for him, my Spanish is horrible. He then did some figuring with his Max prop literature and proclaimed "the pitch angle all wrong.” He re-assembled the prop with the new pitch angle based on vessel length, engine hp, my stats and his "intuition."

I wasn't very hopeful; it was kind of like watching a guy look for a place to dig a water well using a forked stick. They put the boat back in, I stepped on the accelerator and WOW! 3,700-3800 rpm’s under load!!! 9 knots in calm water!!! A miracle!!

All he did was change the pitch angle of the prop.

Here’s a brief history of what happened:

1. The Oyster 53 had a knocking noise when I had it surveyed at purchase.
2. The surveyor diagnosed knocking as a transmission problem.
3. Idiot mechanic serviced the Max prop whilst re commissioning was underway.
4. Departed the UK with vessel able to rev to 2,400 rpm’s which I thought was normal.
5. The knocking went away, but over the course of the next 1800 miles the engine began to rev slower and slower while underway, until it would only rev to 1400 rpm and make 5 knots headway max.
6. 1000 Euros spent on diagnostics… you name it…. It was done.
7. Turbo was removed in Menorca and diagnosed as totally destroyed, by overheating and carbon blockage.
8. New turbo installed… same problem only now we had dark black smoke.
9. Prop pitched changed from 18 degrees to 14 degrees. Problem solved!

It appears now that our poor engine was working way too hard trying to drive the faulty prop pitch; then the fuel management system continued to compensate by throwing more fuel on the fire, which in turn clogged up the turbo with carbon, leading to its ultimate demise. Kinda like driving one’s car around all the time in fifth gear, lugging the engine.

I’m just glad to have it all behind me now. The best 450 Euros I’ve ever spent.

Ken McCallum

P.S.: Other related repairs prior to discovering a solution:
1. Fuel tanks emptied, tanks scrubbed and new diesel from a petrol station filled (not dockside)
2. New injectors
3. Complete engine service
4. Compression check
5. Fuel pressure check
6. Oil pressure check
7. Engine would rev to 3,600 without a load
8. Turbo boost pressure check
9. Turbo rebuilt (which didn't work out) I eventually bought a new turbo

[japarker11]

Can't argue with success!! Could you do a comparison of fuel burn from the RPM before (lugging @ 2500 RPM, knots, gph) to repropped (2500 RPM, knots, gph). If you have any "before" data?

I, too, have an overpropped 4jh3-te. Fully realized that approx 10 hp of 75hp was unavailable. The 1.3 gph @ 2400, 7.2 kn seemed worth it.

Not so sure with your experiences? My top RPM has dropped from 3200 RPM to 2800 also.

Thanks

[Sam McD]

So the plot thickens!
I noticed in the log book for the boat that the injection pump had been removed and serviced after the boats 3rd or 4th trip of 6 it did to Fiji from New Zealand (I’m located in Wellington NZ for Oldwheels who offered to help out. A little far from Ga unfortunately, but thanks for the offer =P)
So I called the old skipper of the boat that ran her for the pervious owner and asked why.

The boat ingested some water from the fuel tank breather into the fuel tank on the way back from Fiji and they notised a small smoke trail a day or two out from NZ. They sailed the rest of the way back, then when they got back, they changed out filters, drained the tank and got the fuel pump checked for water - was all clear.
They tested injectors and found #3 injector was missing its collar and had burnt the tip out completely. The motor had a full work over (compression check, bore scope etc) to make sure the injector tip didn’t score the bore or do any further damage. This was replaced and all other injectors tested ok. An interesting point here is this must have been assembled like this from factory as its never been apart since new. The owner apparently argued the case with Yanmar and Yanmar wriggled out of a warrenty claim on the basis some other 3rd party company was assembling the motors for these boats and they are no longer part of the business bla bla.

The main fuel tank breather was re-routed to the stern of the boat and the original breather is now the breather for the custom forward fuel tank in the bow cabin.

The boat used to make 9.5kts in calm water with 22* prop pitch so I think that rules out the pitch being the problem and the water in the fuel issue leads me back around to the pump/governer/injectors as the most likely culprit.

To answer a couple of the most recent questions:
Is the motor spitting water? Yes – no abnormal issues with the cooling water exiting the exhaust.

Is engine temp normal? – As far as I can tell. The boat doesn’t have a temp gauge, just a overtemp warning light. It doesn’t seem any hotter then it should be, but I have a digital thermometer that I will shoot all over the motor tonight when I’m down on the boat to work out if anything is hot.

Does the turbo spin by hand? Yes – I have checked both sides of the turbo independently, and other then a tiny bit of oil in the compressor housing, the shaft feels free, no bearing play and no bent blades or scratches on the housings to indicate its touching under load. I will take the elbow and filter off and check both wheels at the same time to make sure there is nothing obvious like one slipping on the shaft (not that Ive ever seen that before and I have dealt with a lot of turbos in my circuit racing time in cars).

Do I have a cold start on the pump? Not sure – I have a quick look over the manual and some photos and couldn’t see one that’s obvious. The pump looks to have a heater element option in the intake pipe which my boat doesn’t have, so its possible there is no cold bypass on the 4JH3HTE. But I will take a close look tonight and try that if possible.


Im going down to the boat tonight to run it from a bucket of fuel and check everything else you guys have suggested. I will make a note of some speeds at different RPM as well, but going by what the skipper said about her making 9.5kts at 3500RPM and the prop at 22*, I don’t believe the prop pitch is the problem. Shes definitely down on power!

I will report back tomorrow. Fingers crossed I have some more info.

[Sam McD]

Right. Been at the boat all evening and here is what I found:

We ran the boat up at the dock. We didnt take her out due to weather, but we could load it up and get a similar result. Full throttle in gear = 2000RPM.

• Checked valve clearances - Slightly loose if anything. Set to spec. No change
• Ran the motor on a bucket of fuel with feed and return line in the bucket - No change
• Checked the governor stops - No load RPM high and low - High stop is actually over max RPM so can rule this out
• Checked for cold start over ride - None on this pump as suspected
• Checked the turbo - hmmmm. I'm 50% sure its a dead turbo now.

One thing running the boat at the dock gave me over out in the harbor was the ability to really inspect the exhaust color and discharge. Part throttle up to the point the motor stops gaining RPM, the exhaust was clear and not much sheen on the water. When adding throttle beyond the point the RPM stops climbing, the exhaust does change to a slightly black color and a lot of sheen appears on the water - this kind of indicates it might be unburnt fuel.

I pulled the intake filter and the exhaust elbow off the turbo to have a real good look at it, feel for play etc.

The turbo spins freely by hand, but it does actually have a fair bit of shaft play when moving both ends in opposite directions. If I load both sides of the shaft in the same direction, there is no contact by the wheels with the housing, but if I move them in opposing directions, I can get the wheel to touch and prevent the wheels turning.

In saying that, there is no marking on the housings or the wheels, and I have seen turbos in much worse state then that make boost on petrol cars, but not sure how sensitive a diesel turbo might be to friction etc.

I ran the motor up to 2000RPM in gear without the air filter on, looking directly into the compressor wheel and its spinning, speeding up, slowing down etc, but definitely not over coming the pressure differential and producing boost.

Anyone got any wise ideas on how to confirm a turbo is dead before I order another one?