Black smoke after rebuild

[jimbunyard]

Originally Posted by stepwheel101

...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...

Originally Posted by shakey doug

Please post your local air temp along with your starting procedure including times between each sequence. Once the Engine has started take Rpm until it is smoking then the give the Fuel pump a few good clouts with a hammer, if smoke clears when hit the Metering valve or auto advance mechanism is sticking. If no joy try disconnecting the inlet manifold cold start valve feed pipe or take the unit out of the Manifold. Where you situated? Nearly forgot is it a hydraulic or mechanical Govenor f-Pump?

The listed changes made in the fuel system with no apparent performance changes sorta seem to indicate that the problem lies elsewhere, but diagnostics via written description are notoriously difficult...

The fact that he lost possession of the original pump before identifying it makes determining that he has the correct pump now very important.

[River Cruiser]

I've rebuilt a few Perkins 4-236 engines in JCB backhoes. In my experience great care must be taken when ordering cylinder parts, the rings must be suited to the proper piston and liner depending on engine. If I remember correctly the 4-236 engine parts book had 5 different piston ring part numbers depending on what liners and pistons are used. If I was you I would check the receipts for parts and a parts manual to make sure that whoever ordered the parts didn't make a mistake when ordering from the Perkins dealer.


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[stepwheel101]

Ok, so a couple more days at it… Again thanks all round for the discussion.

I have a couple of new pieces of information, I have been focusing a little more on the transmission end. I was sceptical that the STP may have stopped the rings bedding in properly so I did a full oil change and attempted a second ‘run in’ I was running at fairly high rpm (through full rand but spending most time upward of 2400/2600rpm for over an hour. I didn’t note any difference with the symptoms of this problem however the gearbox did get very hot. Without a temperature gun I don’t have exact temp but it burnt to leave your hand on for more than a second. I was running the engine primarily in neutral, I only had the gear engaged for a maximum of 4-5minutes throughout the hour. Obviously running the engine at high rpm is going to generate a lot of heat so I’m not sure if it has just radiated through the casting or whether it is to do with something internal within the gearbox, a few of you have mentioned heat? Any thoughts appreciated.
I do keep getting a lot of people telling me how ‘bulletproof’ these Borg Warners are, but obviously nothing is invincible…
The other onion in the ointment is that I have been in contact with a Delphi service centre in Manila. He has been rather convincing in telling me that he strongly believes it to be a calibration issue within the pump. He says that if you don’t have access to Delphi data specs you cannot accurately calibrate this style of pump. I am aware that where I have taken them so far the level of knowledge when it comes to these specific pumps has been pretty much zero, not being disrespectful to the technicians here in Davao, they quite simply just have not been exposed to them. Hence this conversation has bought me full circle back to incorrectly calibrated fuel injection pump.
ARRGH!!!...
Again it just takes so much time to get accurate information here, I have spent so much time and money already I am just a bit reluctant to freight my pump away again just on another ‘hope’…..
My next immediate step before removing fuel pump again, is I plan to detach the shaft coupling in an attempt to test if gearbox issue or a load issue. My (uneducated) theory is that by removing the physical load i.e. the propeller pushing water, I can determine whether something in the gearbox loads up at a certain rpm or if the problem is engine related. Can anyone think of any flaws in this pattern of thought???
Other than that if anyone has any information on Delphi pump specs that would also be welcomed.
Thanks again for your time all, Still gratefully appreciated!

[Wotname]

Has any maintenance, repairs or overhaul etc been carried out on the transmission during or since the engine rebuild?

[01kiwijohn]

Now, you're getting there!
You may very well have a transmission problem but, hot enough to prevent hand contact indicates upwards of about 130 deg.F; not disastrous.
Does the trans have a cooling jacket and is it clean, inside?

Franchised fuel injection shops usually either have the right calibration specs to work from AND/OR some kind of direct contact with the manufacturer to help them with unusual case. Good test benches do not lie.
Looks like you're getting to the crux of it. good luck

[stepwheel101]

Hi again,

Today I did another pump change, just for fun… No, I wanted to double check that our max rpm under load did not change. Just to confirm we have only 2 pumps, and I have used only 1 for the majority of testing. During this saga I have learnt that one of the pumps is set up with a lower delivery than what is ideal for my engine, this was the first pump I installed and at that time could only reach 1100rpm. I have not reinstalled this pump until today. The result of today’s test was: I could obtain the now ‘standard’ 1600rpm; had I only reached 1100 with this pump then I deemed it would be less likely transmission related and more likely pump related.

I also totally removed air intake manifold. I had inspected this with light and mirrors but this full removal has satisfied me completely that there is defiantly no shortage of air.

Also to confirm all rpm reading throughout have been using a digital laser tachometer.

So yes it certainly looks like a real potential for gear box problem…
This is exciting as I know nothing at all about gearboxes so what a great learning experience…
Several of you have already mentioned some possibilities of what might be wrong; at this point I am educating myself of the internal workings of the BW velvet drive. I have read in the manual that there is a big warning about ensuring that the GB is hooked up to the oil cooler before starting or cranking the engine – the result being probable blow out of the forward clutch piston –
As the box was working before the overhaul my first instinct is to look at what potential changes could have been made by only removal and replacement. The installation warning stood out. Does anybody know what sort of symptoms might be observed as a result of a blown forward clutch piston?

Other potentially relevant information is that I disengaged the flange and separated the shaft and prop from the gearbox/engine. Result: I could run the engine in gear (but with “no load”) and obtain correct revs approx 2600 or so. Not sure if this can help with diagnosis of particulars with in the box but I thought it may be applicable.

As I mentioned I know very little about these. I have already read several useful threads on rebuilding these particular units but if anybody has any tips for a newbie about to undertake this job I will gratefully receive them, also with the symptoms my unit is displaying what bits I might be needing to order etc. I understand that there are a boat load of tiny bits and pieces and anything could be possible, but some guidance is always appreciated.

Cheers again


Steve

[stepwheel101]

Also wotname,

just to clarify - No, no work was done on transmission only removal and re-attach

[wooden head]

So running the leaner pump you got better performance, and this indicates gearbox issues? I must have missed something. This sounds to me like the other pump is set up too rich. This would be normal for a pump set up for a turbo motor, which has higher airflow under load.

[jimbunyard]

Originally Posted by stepwheel101

Ok, so a couple more days at it… Again thanks all round for the discussion.

I have a couple of new pieces of information, I have been focusing a little more on the transmission end. I was sceptical that the STP may have stopped the rings bedding in properly so I did a full oil change and attempted a second ‘run in’ I was running at fairly high rpm (through full rand but spending most time upward of 2400/2600rpm for over an hour. I didn’t note any difference with the symptoms of this problem however the gearbox did get very hot. Without a temperature gun I don’t have exact temp but it burnt to leave your hand on for more than a second. I was running the engine primarily in neutral, I only had the gear engaged for a maximum of 4-5minutes throughout the hour. Obviously running the engine at high rpm is going to generate a lot of heat so I’m not sure if it has just radiated through the casting or whether it is to do with something internal within the gearbox, a few of you have mentioned heat? Any thoughts appreciated.
I do keep getting a lot of people telling me how ‘bulletproof’ these Borg Warners are, but obviously nothing is invincible…
The other onion in the ointment is that I have been in contact with a Delphi service centre in Manila. He has been rather convincing in telling me that he strongly believes it to be a calibration issue within the pump. He says that if you don’t have access to Delphi data specs you cannot accurately calibrate this style of pump. I am aware that where I have taken them so far the level of knowledge when it comes to these specific pumps has been pretty much zero, not being disrespectful to the technicians here in Davao, they quite simply just have not been exposed to them. Hence this conversation has bought me full circle back to incorrectly calibrated fuel injection pump.
ARRGH!!!...
Again it just takes so much time to get accurate information here, I have spent so much time and money already I am just a bit reluctant to freight my pump away again just on another ‘hope’…..
My next immediate step before removing fuel pump again, is I plan to detach the shaft coupling in an attempt to test if gearbox issue or a load issue. My (uneducated) theory is that by removing the physical load i.e. the propeller pushing water, I can determine whether something in the gearbox loads up at a certain rpm or if the problem is engine related. Can anyone think of any flaws in this pattern of thought???
Other than that if anyone has any information on Delphi pump specs that would also be welcomed.
Thanks again for your time all, Still gratefully appreciated!

Originally Posted by stepwheel101

Hi again,

Today I did another pump change, just for fun… No, I wanted to double check that our max rpm under load did not change. Just to confirm we have only 2 pumps, and I have used only 1 for the majority of testing. During this saga I have learnt that one of the pumps is set up with a lower delivery than what is ideal for my engine, this was the first pump I installed and at that time could only reach 1100rpm. I have not reinstalled this pump until today. The result of today’s test was: I could obtain the now ‘standard’ 1600rpm; had I only reached 1100 with this pump then I deemed it would be less likely transmission related and more likely pump related.

I also totally removed air intake manifold. I had inspected this with light and mirrors but this full removal has satisfied me completely that there is defiantly no shortage of air.

Also to confirm all rpm reading throughout have been using a digital laser tachometer.

So yes it certainly looks like a real potential for gear box problem…
This is exciting as I know nothing at all about gearboxes so what a great learning experience…
Several of you have already mentioned some possibilities of what might be wrong; at this point I am educating myself of the internal workings of the BW velvet drive. I have read in the manual that there is a big warning about ensuring that the GB is hooked up to the oil cooler before starting or cranking the engine – the result being probable blow out of the forward clutch piston –
As the box was working before the overhaul my first instinct is to look at what potential changes could have been made by only removal and replacement. The installation warning stood out. Does anybody know what sort of symptoms might be observed as a result of a blown forward clutch piston?

Other potentially relevant information is that I disengaged the flange and separated the shaft and prop from the gearbox/engine. Result: I could run the engine in gear (but with “no load”) and obtain correct revs approx 2600 or so. Not sure if this can help with diagnosis of particulars with in the box but I thought it may be applicable.

As I mentioned I know very little about these. I have already read several useful threads on rebuilding these particular units but if anybody has any tips for a newbie about to undertake this job I will gratefully receive them, also with the symptoms my unit is displaying what bits I might be needing to order etc. I understand that there are a boat load of tiny bits and pieces and anything could be possible, but some guidance is always appreciated.

Cheers again


Steve

Steve,

The 71C is a hydraulically operated transmission, in neutral the only load it puts on the engine is from the oil being pumped through it to lubricate the bushings and circulate through the cooler. Why disconnecting the prop shaft would make anything more than a very minor difference in rpm is a mystery to me. If there was a fault in the input side of the gear, dragging the engine down, disconnecting the shaft would have no effect. If there was a fault in the output side of the gear, leaving it in neutral would isolate any effect.

If the gear goes into forward, neutral and reverse with no problems, doesn't slip or make any unusual noises, and doesn't overheat (above180F), there is almost certainly nothing wrong with it.

I have seen instances where the mounting to the engine can be an issue, if there isn't enough clearance between the input shaft and the drive plate, a bind can be introduced, though if this were the case the issue would always be present...

From the two posts above, it seems to me the most relevant things you've done are re-run-in the engine at high rpm (good) and switch the pump (diagnostic). If piston ring sealing is/was an issue, an hour at variable high rpms could certainly have caused the rpm differences you note with the alternative pump, that may have been hidden by the (possible) overfueling of the other pump.

It seems that ensuring that you have the right nozzles (either CAV or Delphi), as indicated above from the Perkins service manual, and then trying to ensure you have the correct pump calibration are still your best bets.

To rebuild the transmission is not a trivial thing. You can probably do it, but I wouldn't want it to be my first rebuilding experience unless I had the tools, a good manual, a place to do it and someone first hand to ask advice from.

Do you have a transmission cooler hooked up? Is everything hooked up the same as it was when you removed the engine?

[DeepFrz]

Did the boat sit in the water while engine was being overhauled? If so have you cleaned the prop since?

[Wotname]

Originally Posted by DeepFrz

Did the boat sit in the water while engine was being overhauled? If so have you cleaned the prop since?

According to the OP in post #1, the bottom and prop is clean and prop not fouled on anything.

[stepwheel101]

Ok,

Well this is the most positive I have felt about a solution for some time. I have been in contact with a transmission specialist in Australia, his theory is a combination of things and also that the problem has roots in the distant past…

I have not thought about the prop being the issue because I have not changed it. But that’s not to say that a previous owner didn’t change the prop and in addition to changing the propeller also changed the calibration of the injection pump to compensate for the prop change.
I have come along to do this overhaul, the ‘original’ pump was dismantled/destroyed and that calibration was lost. I return with a pump calibrated to drive a 4108 with a set sized propeller suited to a vessel of my specs… Completely unaware that some bastard has changed the propeller on me (albeit many years ago). The outcome; yes I have most likely become over-propped without even realising.

At this point we are trying to figure out how to re-calibrate the injection pump so we don’t get the overloading symptoms. This will probably mean we cannot achieve ‘maximum’ rpm but should be enough to get us moving reasonably well.



Also what prop i should probably have with a 'correctly' cakibrated inj pump


This is still in the realms of theory at this stage but I will post updates as I can.

As usual thoughts and discussion welcomed.

Cheers –

Steve



in addition to above I have shortlisted relevent specs below



Keira Specs.

LOA – 41’ (12.49m)
LWL – 32’ (9.75m)
BEAM – 12.17’ (3.71m)
WEIGHT – 28000 lbs (~12.5t)
DRAUGHT – 6’ (1.8m)
PROPELLER – 17RH15
TRANSMISSION – Borg Warner Velvet Drive AS7-71C (Ratio = 1.91:1)
ENGINE – Perkins 4108 (# 108491604 & ED700584617374M)

[Wotname]

Hmm...interesting theory and it is an explanation that matchs the observed facts.

I wonder if it possible to test this hypothesis! I can't think of an easy way but there are much greater minds on this thread than mine!

[lancelot9898]

Originally Posted by stepwheel101

Ok,



in addition to above I have shortlisted relevent specs below



Keira Specs.

LOA – 41’ (12.49m)
LWL – 32’ (9.75m)
BEAM – 12.17’ (3.71m)
WEIGHT – 28000 lbs (~12.5t)
DRAUGHT – 6’ (1.8m)
PROPELLER – 17RH15
TRANSMISSION – Borg Warner Velvet Drive AS7-71C (Ratio = 1.91:1)
ENGINE – Perkins 4108 (# 108491604 & ED700584617374M)

I have a 1985 Perkins 4-108 with a Borg Warner Tranny and here are my specs.

LOD 37'
LWL approx. 32
Beam 11.5
Weight 22500(design) 30000(travel lift)
draft 5'8" (design) 5'10 actual
tranny Velvet drive (2.1:1)
engine 1985 Perkins rating 3600 rpm continuous
prop 17 by 11 3 bladed came with boat new in 1985

I never used that prop and changed to a max prop in 1985 using a setting that gave approx. the same pitch of 11 inches.

I was not happy with that pitch since to achieve 7 knots, I had to run the engine at 3000 rpm plus. I wanted a lower cruise rpm and adjusted that pitch up to 14 inches. I cruise at 6 knots at 2200 rpm and my wot is 2800 rpm. I don't get any black smoke even though I am over propped not being able to achieve the 3600 rpm rating of the engine.

So my guess is that you are over propped. But then again so am I and I don't see the black smoke. FWIW

[Eumelia]

3-blade I assume?

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