Black smoke after rebuild

[stepwheel101]

Hello all,

My name is Stephen,

I was wondering if I may be able to intrude into your time for a moment, I have an issue with my Perkins 4108(M) engine and was hoping that someone out there may be able to offer some assistance. I will attempt to be as concise as possible. I have included as much information as I consider being relevant, if you require any more please let me know and I will endeavour to get it online asap.
The engine is in a S/V yacht. The vessel is a CT41 Ketch LOA 41 - Beam 12.17' - LWL 32' - Displ. 28000 lbs
The Engine numbers are – 108491604 & ED700584617374M. Mid 1980's vintage.

The problem presented approximately 5 weeks ago, a full rebuild was completed in October 2014; the engine was run ‘on the bench’ and appeared to function well. The vessel was re-launched on 29 September 2015; at this point we were able to properly sea-trial the engine. The symptoms are: when under no load the engine progresses through the rev range without an issue, until approx 2800rpm – 3000rpm when some black smoke and carbon is expelled through the exhaust (probably an acceptable outcome). However when the engine is under load (in gear) it can only reach a maximum of approx 16-1700 rpm, also at this point there is very thick black smoke and carbon being exhausted (black water discharge with black deposits up to the size of a tennis ball floating on the surface). Up until this point -i.e. 1600 rpm - the engine and power increases as would be expected.
Prior to the overhaul the engine could easily obtain 2400rpm, due to the fact the engine was quite “tired” I did not ever push beyond this rpm range, my usual cruising speed was 1800rpm at which point we would be getting around 5knts. When in gear and over approx 2000-2200rpm the engine did exhaust some darkish grey/black smoke but none of the carbon discharge, which we are seeing now, was noticeable in the exhaust water. I was expecting that after the overhaul I could obtain close to 2800rpm.
After spending over a month completing the troubleshooting list outlined below I have finally managed to obtain an engine compression test kit. The results of the test were that all 4 cylinders generated a pressure of almost exactly 200psi. I have not been able to confirm what the exact pressure should be, however my calculations and research led me to believe that I could expect a pressure of around the 320psi mark, especially with a newly rebuilt unit. Any Perkins knowledge here would be great.

So, the engine has just been rebuilt, top and bottom end, including new pistons, liners bearings oil pump etc. The issue has only been present after the rebuild. I am currently in the Philippines while we have been troubleshooting. Below is my troubleshooting list which I have worked my way through, I have double or triple checked most all of these.
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 down the air intake for any restriction.
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 (first set I ran with I believe were incorrect – Zexel NP-DN4SD24) I have since put in – Zexel 12SD12. I am still not convinced that these are the correct nozzle tip required… I have been told by one source that Delphi 12SD6236 are the only ones suitable?
Injection pump has been serviced & calibrated and I have run the engine with two different pumps with no change in symptoms
Pump numbers Both are CAV pumps –
Pump # 1 (DPA 3247F190) (DSA 128) (EH34E1700/0/4480) (SER R07109TT)
Pump #2 (DPA 3246F997) (DSA BLANK) (EH39/1200/0/4480) (SER 10090 N0)
I originally set the pump up with the timing lines lined up and have adjusted (advanced and retarded) timing many times again with no major change to symptoms.
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. Drip rate is good.
Oil level in gear box is set to the line and looks in good condition. (Borg Warner Velvet Drive AS7-71C)
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 have triple checked prop is not fouled.

So now my main concerns are that I still may have a problem with fuel injection. I have struggled to find solid information on the exact requirements for my specific engine. Both to do with injector nozzles, and the pumps themselves. Unfortunately the original pump which was taken off when the engine was being overhauled was ‘not serviceable’ according to a local here and has disappeared without me being able to even get the numbers from the stamped plate, the old nozzles went before I could check part numbers also. This is now ‘spilt milk’ as far as I am concerned so I must move on. However it has left me with an unknown entity with what the pump (& nozzles) were/should be…

My other concern is now the low compression. The cause for this is the main reason I have contacted you for assistance, I have tried to investigate online as to why this has happened and there is a lot of ‘generic’ information I would like to know some information which is more Perkins specific or 4108 specific as it were. Any information about bore honing/glazing would be appreciated. I am a little dubious about how the engine was run in ‘on the bench’. Also information about what oils would be suitable for running back in these engines post rebuild… or anything you might consider important.

Thank you very much for taking some time to assist me with this, I am getting to the end of my preverbal tether and am really struggling to find reliable information. Again please let me know if any more details would assist you in answering my query? I look forward to reading all your responses.

Cheers all


Stephen

[Wotname]

Hi Stepwheel101, first let me say that I probably can't help you - sorry; but I do want to say "Welcome Aboard" CF. You have certainly thrown the engine experts here a curly one and hopefully some of them will be along soon to provide assistance.

My gut feeling is those compression figures are way too low, especially for a new rebuild and I share your suspicion about how the engine was "run in" on the bench. Started and run I can believe but not "run in".

Can whoever did the rebuild give a feasible explanation of the compression test results?

[jimbunyard]

How difficult (or not) is it to start?

Have you checked valve clearances?

Are you absolutely sure that the gear train timing is correct?

That there is no change when changing the pump and injectors is revealing, the problem comes in determining what is being revealed.

200 psi is very low, low enough to question the accuracy of the reading,
especially with a new rebuild, unless something was misassembled or some part is not to spec. Unless you ran the engine at idle for an extensive time after start-up, it seems unlikely that you've glazed the cylinders.

At 22:1, compression should be 323 at sea level.

In case you don't have one there's a service manual here:

http://www.boatservicehaarlem.nl/per...shopmanual.pdf

[GordMay]

Greetings and welcome aboard the CF, Stephen.

[a64pilot]

Being that they are all low, almost certainly cam timing. I don't see anything else that could make all compression low, and cam timing will kill power too, all it has to be is off a tooth


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[HappyMdRSailor]

Originally Posted by Wotname

Hi Stepwheel101, first let me say that I probably can't help you - sorry; but I do want to say "Welcome Aboard" CF. You have certainly thrown the engine experts here a curly one and hopefully some of them will be along soon to provide assistance.

My gut feeling is those compression figures are way too low, especially for a new rebuild and I share your suspicion about how the engine was "run in" on the bench. Started and run I can believe but not "run in".

Can whoever did the rebuild give a feasible explanation of the compression test results?

Wotty... This is a curly one for sure!

I think the pilot has it below...

Originally Posted by a64pilot

Being that they are all low, almost certainly cam timing. I don't see anything else that could make all compression low, and cam timing will kill power too, all it has to be is off a tooth

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Bravo Mr. P..... I suspect you are right... If not, we've got some serious sealing issues in the holes....

Welcome to CF Stephen!
Hopefully we'll get this sorted out...

[beetlejuice30]

I'll agree with timing, sounds like your not getting full combustion.
Rebuilt a few cummins that where sunk a few years back (rust crusty)
Needed to get a offset key way to correct the timing. Other things that Pop to mind are the governor or control rack on the injector pump.
Good luck


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[Xthewater]

Stephen:

It sounds to me like the compression rings have been installed upside down in which case you will get all the symptoms you've described.

[beetlejuice30]

Originally Posted by Xthewater

Stephen:

It sounds to me like the compression rings have been installed upside down in which case you will get all the symptoms you've described.

This crossed my mind as well buy yikes that's a beginner move. Hopefully he got the ring gap right and in the right placement. There is normally a small dot or letters on the rings this faces up!!!


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[Xthewater]

Originally Posted by beetlejuice30

This crossed my mind as well buy yikes that's a beginner move. Hopefully he got the ring gap right and in the right placement. There is normally a small dot or letters on the rings this faces up!!!


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It happens but there's only one way to verify. I hope there is a warrantee involved here.

[HappyMdRSailor]

We all agree the lack of compression is the issue... Let's hope it's the timing gear and not the dots on the compression rings...

(oh, and I clearly missed Jim as the first poster of the valve timing possibility... Maybe it's cause I think Pilot is such a smart guy?)

[model 10]

Originally Posted by a64pilot

Being that they are all low, almost certainly cam timing. I don't see anything else that could make all compression low, and cam timing will kill power too, all it has to be is off a tooth


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I'm not so sure. Any amount the valve is open is going to result in just about 0 compression. 200 psi is what 13:1? That is a pretty good valve seal. I don't think the valves are open at tdc.

[Seman]

Hi Stephen, looks like I've had a similar problem after a rebuild.
I think around 200 PSI, +- 15 % is what I've had.
The very valuable info from the Forum is here:

http://www.cruisersforum.com/forums/...ion-98682.html

Good luck, Cheers

[paulfl]

Having it rebuilt where you did I would tend to look at the rebuilder for something that went wrong.
Something that comes to mind is that if the piston liners come in different sizes there might be the possibility that wrong liners were installed.
Hope that's not the case.

[Daveee]

Hi Iv had compression problems before when when the new liners are pressed in they press them in flush to the block face when they need to be proud by 20 thou so head gasket sits round them . ..just a thought ⚓️