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Hi all,

I have been reading these posts and have helped me a lot, unfortunately I have a problem which I have not been able to find a solution to so I am putting it out to the wider community in the hope for some assistance.

We are currently docked in Philippines.

Engine is 50 hp Perkins 4108. Was overhauled by local mechanic last year (2014) bench test was all good. Sent injection pump for overhaul/service and once returned engine ran terribly- much black smoke and thick black exhaust ‘gunge’.
Returned with new pump from Australia this year and also had spare pump serviced and calibrated by local Bosch injection service technicians. We installed the newly reconditioned pump and engine ran very well in neutral. We launched the boat approx 1 week ago and since then have been able to load test which is where the problems started. The Vessel was out of the water for almost 18 months undergoing major refit.

Symptoms are....

In neutral (no load) engine will move through rev range up to approx 3200 rpm as expected ~ clear exhaust with only a bit of black when very close to WOT (upwards of approx 2800rpm)

Once gear is engaged (fwd or reverse) engine will operate normally at idle speed (approx 6-700 rpm) then accelerate typically (clear exhaust and prop/boat speed) up until approx 1100 rpm after which point much black smoke is noticeable and black ‘gunge’ is in the exhaust and floating on the water (appears to me be improperly combusted diesel).
There is still throttle left but as you accelerate further there is no increase in prop speed/boat speed or rpm increase, just more black smoke/’gunge’.

I have run tests tied to the dock and out on sea trial with no change to the symptoms.

I have checked throttle morse (removed and accelerated manually)

I have checked the stop morse (removed to ensure it was all the way in the open position)

I have removed the air filter (engine is naturally aspirated i.e. no turbo)

I have removed and inspected exhaust manifold, elbow and water trap/muffler box. All were completely clean

I have checked and changed all fuel filters.

I have inspected all fuel lines and replaced any suspect.

I have run with fuel line assisted by electric pump to aid if lift pump was having difficulties. (also with a temporary ‘day-tank’ set up higher than the engine.

I have removed and replaced all injectors

Injection pump has been calibrated and I have run the engine with two different pumps with no change in symptoms

I originally set the pump up with the timing lines lined up and have adjusted (advanced and retarded) timing again with no change to symptoms.

I have checked valve clearance and found No.3 cylender to be out by 0.1mm[ should be at 0.3mm but was found to be at 0.4mm (I have not had a chance to tune and check as was beaten by the light)] but will do so in the morning. Could be causing this issue?

Gear box is Borg Warner velvet drive; it was not serviced during the overhaul. Is there anything you know of with these that would cause an overloading problem like this? It goes into fwd and reverse with no problem.

Shaft was aligned and feels fine on rotation (no vibration or stiffness), stern gland is not overheating, and shaft spins freely by hand when in neutral.
Oil level in gear box is set to the line and looks in good condition.

The propeller is the same as before the overhaul.

As we have just gone back in the water all the bottom and prop is clean

I am genuinelly running out of ideas, hope someone out there may be able to shed some light....

Cheers already

Steve
 

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HANUMAN
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You will get much better ideas than this, but, the first thing I might do is put on a mask and double check that the prop is in order and spinning freely in neutral. I know you just launched but a wrap of line or netting or maybe something happened during launch (were you present when the boat went back in the water?). It's a long shot, but it doesn't involve taking anything else apart.

No chance of an exhaust hose collapsing or bending?
 

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In neutral (no load) engine will move through rev range up to approx 3200 rpm as expected ~ clear exhaust with only a bit of black when very close to WOT (upwards of approx 2800rpm)

Once gear is engaged (fwd or reverse) engine will operate normally at idle speed (approx 6-700 rpm) then accelerate typically (clear exhaust and prop/boat speed) up until approx 1100 rpm after which point much black smoke is noticeable and black ‘gunge’ is in the exhaust and floating on the water (appears to me be improperly combusted diesel).
There is still throttle left but as you accelerate further there is no increase in prop speed/boat speed or rpm increase, just more black smoke/’gunge’.

>>>>>>> I have checked valve clearance and found No.3 cylender to be out by 0.1mm[ should be at 0.3mm but was found to be at 0.4mm (I have not had a chance to tune and check as was beaten by the light)] but will do so in the morning. Could be causing this issue?
Assuming you correctly reset the fuel timing of the injector pump ....... IF not, FIRST recheck/reset FUEL INJECTOR TIMING. Then if not corrected:

A. Do compression test or pressurized air-leak-down test looking for partly blown head gasket (possibly between cylinders).
.... OR a 'floating' / hanging-up valve stem that isnt fully withdrawing from the combustion chamber thus the valve not fully closing and not allowing a cylinder to develop full compression due to valve leakage.
Could be as simple as rust on a valve stem that is 'slowing' the spring return action of the valve - causing the 'float' at high rpm under load.

B. Remove the injectors, looking for sooted injector tip(s), the one with the 'blackest' tip will indicate which cylinder is not reaching full compression. If so, then measure the 'stroke' dimension (to closest 1/1000th of inch, etc.) of the valve travel distance for that cylinder. If rusted valve stem, sometimes soaking the valve stem seal(s) with a bit of 'penetration oil' will help to re-polish a stem that is not working (hanging-up) correctly. Also look for camshaft lobe that has abnormal wear.

C. If there is a high probability of head gasket leak and the exhaust gas is leaking into the fresh water cooling circuit ... there are dyes that can be put into the fresh water and which will 'fluoresce' when 'black light' is shown into the water and the water has a high amount of carbon monoxide from a head gasket leak.

D. If the engine has ever had water in a cylinder - Another possibility is a hanging up piston ring with the possibility that the ring groove is rusted or filled with soot and the ring is not fully following/expanding .... in a worn cylinder bore that has developed a 'taper'. A rusted piston groove would be an indication of water leak into the combustion chamber, either from a blown head gasket OR an exhaust manifold that has developed a pin-hole leak from the 'water side' to the 'gas side' (water enters the cylinder after the engine is shut down ..... in such cases of water leak, the removed injector tip will be the 'easiest cleanest' but sooted and the soot 'easily' wipes off, continuously cleaned by the steam generated but sooted due to the low compression in that combustion chamber due to 'sticking' piston ring.
Remedy for crudded up piston ring groove .... remove all injectors, inject penetrating oil into suspected cylinder, let soak for several days, then spin engine by starter, let soak a few more days ..... and repeat a few times followed by running engine slowly from low rpm/no load and
'slowly' from previous to high rpm/full load .... over several hours - to repolish piston ring groove, ........ then look for source of water leak into the combustion chamber that probably caused this - head gasket or leaking exhaust manifold, etc.

good luck, hope this helps.

added/edit ... an engine with a stuck/sticking piston ring will usually have a lot of 'blow by', as noted by a lot of 'gas' coming out the 'block breather' or removed lube oil cap.
 

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Rich seems to know a lot more about diesels than I do. Black smoke oil burning. Smoke while running under load compression. I will have to reed that post again and remember
all those other possibilities. Woah neat.
 

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When the black smoke starts is there a new 'ticking' noise too? That would point more definitively to a poorly atomizing injector (breaking over at too low a pressure). This has been known to occur even with newly reconditioned injectors from time to time. It also generally causes a drop in rpm.

In my experience oil burns blue, poor diesel burn is black, and antifreeze/coolant burns white as a general diagnostic indicator..

I think I'd be looking into Rich H's first point first.. the actual timing of the injection pump - and of the whole valve train too.
 

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Discussion Starter #6
Hey all,

Thank you for your responces, really appreciated.

Rich, I am going to recheck the inj pump timing. I was in the shop when the technicians were calibrating and I know that
1. they do not have a timing tool and
2. they did not hook it up to an atomiser tester as per manual instructions for re-timing the pump without tool. lets hope that is the case.

Also the engine has JUST been completely overhauled top and bottom I can see no signs of corrosion on rocker gear, I would hope that corrosion is no the issue.
I suppose a head gasket could be damaged before or during installation?
I have had the same symptoms with 2 different sets of squirts (injectors)
The engine was stored dry, since the rebuild I think highly unikely that water got in, but then straner things have happened...

With the floating valve stem... I have read in the overhaul manual that the engines are not manuactured with a valve seat, just machined correctly, over time the valve seats wear and if overhauling if valve clearence is beyond tollerance then valve seats will need to be installed. If these were needed and the mechanic has not installed them could this be related to my symptoms?

Thanks again for taking your time... I will let you know how re inspection of pump timing goes


~ Steve
 

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I'm not specifically familiar with the 4-108 but for most other diesel engines of this type, the fuel timing is set by placing or removing appropriate shims installed between the body of the injector pump and its mating opening in the engine block, so that when an indicator scribed 'mark' on the crankshaft nose (or pulley mounted to the crankshaft nose) lines up typically with an embossed 'mark' on the block, so that the pump opens and the #1 injector correspondingly opens and pumps oil. Retarding or advancing the injector timing is accomplished by changing the amount of shims between the injector pump and the mating surface on the engine block.
So the easiest way to do this, is to ask the mechanic who did the rebuild if he actually set the timing correctly when this engine was reassembled after its rebuild.
Most shop (maintenance and rebuild) manuals have this is info on how to check and how to adjust, etc.

;-)
 

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Closet Powerboater
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What is the quality of the diesel fuel? Any chance you got diesel mixed with bunker fuel? (It has happened)

Sent from my SAMSUNG-SGH-I537 using Tapatalk
 

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You have not responded to the question of prop being fouled. A fouled prop could cause these symptoms as well.

Tod
 

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Discussion Starter #11
Hi All,

Sorry for delayed response but internet coverage had been non existant.

First up, dove on prop and tripple checked no fouling there... to be honest i almost wish i had found somthing...

Next update, I took the inj pump to the shop and personally did the timing as per manual specs. I re-installed pump and max rpm (under load) dropped to approx 800rpm, I then advanced (or maybe retarded timing by external method) and achieved just under 1400 rpm (before back smoke/gunge) a new record since rebuild.

I spun the pump the other way and rpm under load changed to pprox 1000rpm still smoking.

My thoughts now go to internl timing... does anyone know if it is possible that the crankshaft may be 180 degrees off? and the engine still run but then struggle under load?

Any other timing methods for these 4108's woud be appreciated.

I am convinced its timing, now just need to figure how to remedy, any and all perkins peoples!

Even a way to test crankshaft theory without ripping the front off would be a start.

Thanks again all, very much appreciate the assistance


Cheers - Steve
 

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Closet Powerboater
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Give Stewart's marine in Ballard Washington a call. The guy who runs the place (I think his name is Stewart) looks like Billy Bob Thornton from U-Turn. He is amazing with Perkins engines and helped me over the phone once when I was in a bind.

If he helps you out you could repay him with a nice Yelp review.

Stewart Marine Engine & Machine Works - Ballard - Seattle, WA - Reviews - Yelp
 

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I forgot to mention one the most simplest things that will make an engine smoke like hell ..... check the tightness of the stuffing box and check the 'warmth' of the stuffing box when in gear.
A too tight stuffing box will act as a 'prony brake', bleeding off LOTS of Horsepower and will cause the engine to 'lug' (slower than normal rpm AND high combustion chamber pressure.

Rx: run the engine in gear at near full load / cruising speed, then put you hand on the stuffing box; if hot or very warm ...... probably the cause of the 'smoking' at high rpm under load.

;-)
 

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The velvet drive can try to be in both gears at the same time. Usually happens when run ahead hot , low oil, and then quick change to reverse The pistons that controls band and disk position doesn't do what's needed. this control gets oil from a geroter pump on the input shaft and I've replaced several, even on a new (rebuilt) gear!! As an aside, this pump only works when engine is turning and so tranni cooling under sail doesn't happen. Borg says 'no problem ' but I have my own opinions.
 

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engine was apart, did you check cam shaft timing one tooth off and it would run but not good
Was the drive gear removed from the cam shaft? the gear and cam should have a scribe line done at the factory to realign the two as the gear has slotted holes used to set the timing. same thing on the injection pump drive.
 

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i am not familiar with this particular engine, i will give you generic guidance...keep in mind that black smoke means too much fuel.....or not enough air...or put that another way, the engine in its present condition is incapable of burning all the fuel that is being injected

as this all started following an overhaul and reading what you have done so far, i would check everything is in order with the air side
air filter, take it off until this is all sorted out, find a way to look or feel down the inside of the air piping / passages to make sure they are clear all the way to the head / inlet valves. air manifold, make sure the gasket is not partially blocking the air holes (wrong gasket installed??)...inlet valves, can you measure the valve opening travel, and check where it is happening in relation to your crank angle, you are trying here to determine the camshaft is installed correctly. I take it the camshaft was not replaced ?? if it was it might be the wrong one was fitted.
Camshaft timing, manual should tell you how to do this...you could easily be getting not enough air if the camshaft timing is incorrect.

describe better please what is coming out of exhaust...gunge??? do you have water cooled exhaust ? when the engine was "bench" tested what does that mean ?? run in the shop with nothing being driven ? therefore no load ? was there water discharge through the exhaust at that point ? not trying to give you the inquisition but cant comment meaningfully without better info / description. your post :.....(2014) bench test was all good. Sent injection pump for overhaul/service and once returned engine ran terribly- much black smoke and thick black exhaust ‘gunge’. ...trying to understand if this was when running "on the bench" or after you had reinstalled the engine in the boat.....and thus trying to understand where the problem started, with the engine overhaul or with the fuel pump recalibration.

the engine ran without smoking before your overhaul did it ? and its the same transmission and propeller ?

will give you next step when you respond
 

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Discussion Starter #17
Hi all

Thanks for the replys...

Dragon lady I just typed a long response and accidentally deleted it so sorry if this sounds a little rushed in reply...

A quick update... today I removed timing cover to check that, all the dots and marks were where they should be. I checked that no 1 piston was at TDC compression and v/v timing and clearence are good. At this point i was also able to confirm that fuel pump timing was correct (injection point is at 18 degrees BTDC) and all the marks line up.

The fuel pump timing ajustments I did before timing cover removal and I managed to get a stable 1750 rpm and the engine sounded well

Further description-
'gunge in exhaust' - once the engine reaches a certain rpm under load ( now approx1700) the exhaust emmits a dark smoke and the water looks black as it is discharged, The dark emmission which looks like carbon to me, floats on the surface in patches varying from the size of a fingernail to the size of a softball.

After rebuild bench test was done at the shop under no load.
After initial test the inj pump was removed to be 'serviced' once reinstled enine woud not even run in idle without emmiting this black exhaust, also sounded very rough.
I returned 8 months later from australia wi th a new(recond) pump and I also had a spare one which was on board overhauled by local technicians here in Philippines.
The injectors were done over here as well. I am now starting to question the quality of these. Do you know if it is possible that these nozzels might be close to what I need in my engine but are ust not quite right? i.e. delivering to much fuel when those higher loads are required?

So the lon and short o it is I do not know for sure whether the probem strted before or after injection pump wsa 'serviced'

Please let me know if u need some more info, I am really starting to clutch at straws now... and my eyes keep closing while i type.

Thanks again

Steve
 

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I had same black smoke one my one cylinder and tried 3 different rebuilt injectors and one of them was better but still not good . then I changed to a new one and no smoke, problem solved. Yanmar tech was charging $150 each for rebuilt nozzles. then I bought new one from Yanmar and it was only $100.
 

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Never considered that injectors might vary in fuel volume delivery but that makes sense... so question then is will an injector that's 'too big' fuel wise actually fit? ie- same physical thread? These are new-to-you injectors?
 

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If new injectors don't solve the problem, here's a straw to clutch at. Saw that black floater stuff on a Yanmar singl cyl..After a lot of grief, turned out to be the precombustion chamber( pressed into the head) had not been installed correctly at the rebuild shop. May not apply but there you are.
 
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