MD6A Fuel pump questions?

Oct 30, 2019
34
Several years I was I believe well advised with regard to our engine: "If it starts easily and runs smoothly, just change the oil and filters regularly, clean the air filter annually and otherwise try to touch it as little as possible. If it seems happy, just leave it in peace."

We've followed this philosophy with good results, but sadly the point has come where I believe I'm forced to disturb the status quo: Over this summer's cruise, we've been down on power and kicking out black smoke; though I think the former is as a result of the latter, insofar as we're holding the revs down, to avoid the smoke. If we actually gun the engine hard, it responds as well as ever, but belches out clouds of black smoke and a stream of soot from the exhaust - there may be some diesel coming out too, but I don't believe this grunge has a significant oil content. On the basis of these symptoms, I believe that the injector nozzles might be past their best, but also that the fuel pump timing is retarded? That said, I'm a long way from being an expert' when it comes to diesel engines - actually, I probably need to cover some distance before I reach competent!

Any opinons/comment regarding my diagnosis would be appreciated.

Moving on to a cure - assuming I'm on the right track: The injector nozzles are easy enough, I'll just remove the injectors complete, seal up the holes into the cylinder head and take them back to a friend (who is competent) in the UK to get them cleaned and serviced or if needs be replaced, whatever he advises.

The fuel pump timing I need to address myself, I remember seeing an article (I think off this forum) some years ago, which I copied but can't now find, that suggested that there's a pretty big comfort zone to the settings and that you can adjust it by ear/sight. But in which direction ought I to be turning the pump? On the basis that I'm looking at it from the front/saloon end, does it advance (a) clockwise/right/toward the engine block/port side? or (b) anti-clockwise/left/away from the engine block toward the boat's starboard side? Secondly, as a starting point, how many degrees of turn is a likely to be necessary? Are we talking 3-5 or 10-15 degrees here? Finally, how do you physically get the fuel pump to turn? Whilst either my strap or chain wrench might well go around the unit and get a firm grip, I'm not sure that there's enough space to turn them once they're fitted. Is it possible to tap the pump around in the correct direction with a
hammer & punch/blunt screwdriver?

Any and all advice will be appreciated.

Bob Carlisle
Spring Fever 1776

[Non-text portions of this message have been removed]
 
Sep 24, 2008
346
Bob
The symptoms you are describing are exactly what would happen if your
exhaust elbow was restricted by a carbon build-up. When was it last checked?
A diesel needs clean fuel, compression, and air - lots of it. Air works 2
ways, in and out. If he exhaust is restricted the engine cannot bring in
enough air for complete combustion, has less power and the exhaust is black
with soot from unburned fuel.
 
Jul 5, 2006
49
Bob,

I think your thought to take out the injectors and have them tested is the best
first step. In all likelihood the nozzles (where the fuel sprays out of) are
worn (holes are now too big) resulting in an over-rich fuel/air mixture which
would result in the black smoke/carbon discharge from the exhaust. Rebuilding
the injectors and replacement of the nozzles should correct your problem. I wouldn't mess with the injector timing unless necessary. From you description
everything else seems to be behaving just fine.

Fair Winds!

Bill McCourt
Reston, VA

________________________________
From: Bob Carlisle bobnlesafloat@...
To: albinvega@yahoogroups.com
Sent: Wed, October 27, 2010 12:06:23 PM
Subject: [AlbinVega] MD6A Fuel pump questions?


Several years I was I believe well advised with regard to our engine: "If it
starts easily and runs smoothly, just change the oil and filters regularly,
clean the air filter annually and otherwise try to touch it as little as
possible. If it seems happy, just leave it in peace."

We've followed this philosophy with good results, but sadly the point has come
where I believe I'm forced to disturb the status quo: Over this summer's cruise,
we've been down on power and kicking out black smoke; though I think the former
is as a result of the latter, insofar as we're holding the revs down, to avoid
the smoke. If we actually gun the engine hard, it responds as well as ever, but
belches out clouds of black smoke and a stream of soot from the exhaust - there
may be some diesel coming out too, but I don't believe this grunge has a
significant oil content. On the basis of these symptoms, I believe that the
injector nozzles might be past their best, but also that the fuel pump timing is
retarded? That said, I'm a long way from being an expert' when it comes to
diesel engines - actually, I probably need to cover some distance before I reach
competent!

Any opinons/comment regarding my diagnosis would be appreciated.

Moving on to a cure - assuming I'm on the right track: The injector nozzles are
easy enough, I'll just remove the injectors complete, seal up the holes into the
cylinder head and take them back to a friend (who is competent) in the UK to get
them cleaned and serviced or if needs be replaced, whatever he advises.

The fuel pump timing I need to address myself, I remember seeing an article (I
think off this forum) some years ago, which I copied but can't now find,
that suggested that there's a pretty big comfort zone to the settings and that
you can adjust it by ear/sight. But in which direction ought I to be turning the
pump? On the basis that I'm looking at it from the front/saloon end, does it
advance (a) clockwise/right/toward the engine block/port side? or (b)
anti-clockwise/left/away from the engine block toward the boat's starboard side?
Secondly, as a starting point, how many degrees of turn is a likely to be
necessary? Are we talking 3-5 or 10-15 degrees here? Finally, how do
you physically get the fuel pump to turn? Whilst either my strap or chain wrench
might well go around the unit and get a firm grip, I'm not sure that there's
enough space to turn them once they're fitted. Is it possible to tap the pump
around in the correct direction with a
hammer & punch/blunt screwdriver?

Any and all advice will be appreciated.

Bob Carlisle
Spring Fever 1776
 
Oct 31, 2019
230
Sounds like rings to me, Bob. Why not pull the engine over the winter
and replace the rings, re-seat the valves etc. , and reno the injectors
and pump? Your motor will be good as new, next year. I did two years
ago and am very happy with the results. BTW all the bearings were good
as new after all these years.



Trev

From: AlbinVega@yahoogroups.com [mailto:AlbinVega@yahoogroups.com] On
Behalf Of Bob Carlisle
Sent: October 27, 2010 12:06 PM
To: albinvega@yahoogroups.com
Subject: [AlbinVega] MD6A Fuel pump questions?





Several years I was I believe well advised with regard to our engine:
"If it starts easily and runs smoothly, just change the oil and filters
regularly, clean the air filter annually and otherwise try to touch it
as little as possible. If it seems happy, just leave it in peace."

We've followed this philosophy with good results, but sadly the point
has come where I believe I'm forced to disturb the status quo: Over this
summer's cruise, we've been down on power and kicking out black smoke;
though I think the former is as a result of the latter, insofar as we're
holding the revs down, to avoid the smoke. If we actually gun the engine
hard, it responds as well as ever, but belches out clouds of black smoke
and a stream of soot from the exhaust - there may be some diesel coming
out too, but I don't believe this grunge has a significant oil content.
On the basis of these symptoms, I believe that the injector nozzles
might be past their best, but also that the fuel pump timing is
retarded? That said, I'm a long way from being an expert' when it comes
to diesel engines - actually, I probably need to cover some distance
before I reach competent!

Any opinons/comment regarding my diagnosis would be appreciated.

Moving on to a cure - assuming I'm on the right track: The injector
nozzles are easy enough, I'll just remove the injectors complete, seal
up the holes into the cylinder head and take them back to a friend (who
is competent) in the UK to get them cleaned and serviced or if needs be
replaced, whatever he advises.

The fuel pump timing I need to address myself, I remember seeing an
article (I think off this forum) some years ago, which I copied but
can't now find, that suggested that there's a pretty big comfort zone to
the settings and that you can adjust it by ear/sight. But in which
direction ought I to be turning the pump? On the basis that I'm looking
at it from the front/saloon end, does it advance (a)
clockwise/right/toward the engine block/port side? or (b)
anti-clockwise/left/away from the engine block toward the boat's
starboard side? Secondly, as a starting point, how many degrees of turn
is a likely to be necessary? Are we talking 3-5 or 10-15 degrees here?
Finally, how do you physically get the fuel pump to turn? Whilst either
my strap or chain wrench might well go around the unit and get a firm
grip, I'm not sure that there's enough space to turn them once they're
fitted. Is it possible to tap the pump around in the correct direction
with a
hammer & punch/blunt screwdriver?

Any and all advice will be appreciated.

Bob Carlisle
Spring Fever 1776
 
Oct 31, 2019
163
Thanks for the replies/advice to last weeks query:

Whilst there are a few barnacles on the prop, there aren't enough to have this degree of effect.

Note the suggestion regarding renewing rings and re-grinding valves. This goes against my policy of disturbing the engine any more than I'm forced to, besides which, if the rings/bores were knackered, I would expect to have poor compression/starting and also more oil being thrown out of the exhaust? If the injector nozzle replacement doeasn't cure things, I may consider it at the end of next summer.

On this same basis, I'll see if the new injector nozzles improve things and if so I'll leave the fuel pump timing alone.

The heads-up on the exhaust elbow was very well timed, albeit indirectly; whilst we didn't have much carbon build up in there, having taken it off, we discovered that there was a pinhole almost burnt through the casting, which the acid we used completed; fortunately it's near the middle of the unit, so we can hopefully repair it using exhaust tape & epoxy. More seriously, we found that the morse throttle cable, where it passed behind the elbow had been rubbing on a metal bracket which had worn through the outer casing and part way through the cable too; so today I've replaced and re-routed it. Whilst neither problem was connected with my original enquiry, if I'd not taken off the elbow as suggested, the chances are that one or even both of them would've bitten us at a time when they might've caused us some serious grief. Thankyou!

Now its just the injectors, anyone got any good tips for removing them? The last/only time I've done them before, I simply disconnected the unions and hold-down nuts and levered them out with very little effort, using a couple of big screwdrivers; it took about tn minutes. I've learnt today that I was obviously lucky last time, because they won't budge at all this time. I've doused them with WD40 and given up for today, but any ideas on what else I can do will be gratefully recieved.

Bob Carlisle
Spring Fever 1776
 
Oct 19, 2019
921
Albin Vega 27 Limerick
Hi Bob,
a tip that I was given by a mechanic (though never tried myself) is to
partly loosen the hold-down nuts then crank the engine. It will "try" to
start and the compression should shift the injectors.

Obviously you don't completely unscrew the nuts .... :)

Sounds like it should work..

John V1447 Breakaway

On 01/11/10 15:13, Bob Carlisle wrote: Now its just the injectors,
anyone got any good tips for removing them? The last/only time I've done
them before, I simply disconnected the unions and hold-down nuts and
levered them out with very little effort, using a couple of big
screwdrivers; it took about tn minutes. I've learnt today that I was
obviously lucky last time, because they won't budge at all this time.
I've doused them with WD40 and given up for today, but any ideas on what
else I can do will be gratefully recieved.
 
Apr 25, 2008
64
Bob, another professional tip is to give them a good spray of pb blaster once a day or so for a week. WD40 is just not a real penetrator, PB Blaster is sort of a wd40 on steroids, can find it just about anywhere. used to restore some old british sports cars, Pb blaster was the ticket for all the old mangled bolts and fittings. Good luck. Helps if you drink a beer after spraying them each time, sort of a job well done.

karl
 
Feb 13, 2010
528
Bob I tried the epoxy thin om my izuzu marine diesel without any
sucess. I got a plastic bucket up against my elbow and it melted the
bucket. Epoxy losses about half it's strength at 150 deg and gets
progressivley worse the higher the temp goes.I would take it to a
welding shop and get them to weld or braze it. If you're elbow is
stainless as is mine be shore they weld with stainless.

Doug
 
Oct 30, 2019
1,459
Bob, if it's cast iron, and an isolated pinhole, you might try brazing it (with brass rod and welding torch). I've had some success doing this with cast pieces. The beauty of it is that you don't overheat the iron to make the repair, which can cause stress cracks, just enough heat to get a fluxed brass rod to flow into the hole and stick.

In the epoxy department I'd recommend "JB Weld"

Peter
#1331 'Sin Tacha'