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
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.
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
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.
level in gear
box is set to the line and looks in good condition. (Borg Warner Velvet Drive AS7-71C)
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.