Strange governor behaviour

[Timleech]

Setting off from Keadby to head up the tidal Trent to Cromwell a few weeks ago, I opened the engine up to a bit over 800 rpm and was alarmed when it almost immediately dropped back to about 650, after no issues at all in maybe 500 hours. My first thought was fuel starvation, not what was wanted in that situation. Eased down, & then back up to just under 800, with some trepidation, and watched & listened all the way up to Cromwell but it didn't hesitate or miss a beat.

Filters etc had all been checked 150 hours previously, the primary filter in particular as a precaution just the day before, but I went through everything again when in a position to do so, everything was fine.

 

Normal cruising has been in the 400 to 650 rpm range on canals & smaller rivers, 650 gives up 6mph in open water.

 

Last week did some experiments coming down towards Cromwell, and found exactly the same thing happened, and it was reproducible. The revs would drop down alarmingly for a few seconds, then briefly back up, then down for a few seconds again. Extreme, long period, hunting but with longer at the lower speed than the higher. Reducing the load by cutting back the hydraulic pump displacement didn't affect the result, so it clearly was not fuel starvation.

 

Then did more experiments on the wide deep stretches of the lower Witham towards Boston, and found that by going well above 800 rpm it settled down again, at least for the short periods that were practical without building up excessive speed.

 

I'm mystified as to why this should be happening, especially just for a limited range of throttle setting. It hasn't happened before when I've been in a position to use that sort of power, eg on the Thames tideway or Mersey/Ship Canal.

 

I had used parts from two governors to make up a decent set of parts. All the ball bearings were renewed, the setting up adjustments were done by the book.

The pump top and lift pump were professionally overhauled.

I did have to strip it all down later to clean out the cambox bores and fit new pump cams and a decent set of oversize tappets, and probably just bolted everything back together without redoing the settings, but don't really understand how that could have this effect. I shall of course take the book with me next trip and check all the settings.

 

Any suggestions as to the cause?

 

Incidentally the run up the Trent has done wonders for the exhaust, it was getting quite smoky until thoroughly warmed through, after pottering along the Leeds & Liverpool at not much above tickover most of the way. It's now as clean as I could hope for, with just a hint of smoke when cold.

The engine may not have been working particularly hard, but 6 hours non stop steady work has done the trick.

 

Tim

 

[by'eck]

Maybe a long shot but could it be prop loading aided by a sluggish governing?

 

I occasionally get something similar as the boat accelerates (relative term ) coming out of river locks. Also when approaching locks from downstream as the weir induced turbulence causes all sorts of funnies in the flow of water under the hull.

 

On the same note (pun?) I can often hear when the prop is biting as revs drop as the boat speed increases.

[RLWP]

I wonder if it is something sticking and letting go. The governor isn't reacting cleanly

 

Or... The other time I have seen odd behaviour is when one cylinder stopped firing, then cuts in again

 

Richard

Edited September 17, 2014 by RLWP

[steamraiser2]

I'm more inclined to think that its air in the system.. You ought to eliminate that first

[Black Country Lee]

IMHO it sounds like either a ) a small piece of crud holding back an injector, b ) a sticky injector or c ) a small pocket of air partially sneaking through on the vibration on acceleration.

 

Lee.

Edited September 17, 2014 by Black Country Lee

[Timleech]

I'm more inclined to think that its air in the system.. You ought to eliminate that first

 

I had considered that possibility, but more or less (not completely) ruled it out because

 

1) there are no apparent fuel leaks when standing. The one possible source I considered was the changeover valve on the Gardner duplex primary filter, which is at roughly the lowest point in the system and on the suction side of the lift pump. Fuel level in the tank can be above or below injector pump level, but is always above the primary filter. Feed to the primary filter is from the bottom of the tank, via a gauze duplex strainer.

 

2) when the revs drop off, there is no coughing and spluttering, it seems to be running smoothly on all cylinders.

 

I really need to arrange to watch the pump rack while someone else drives the boat and reproduces the symptoms, but it's not something that can be done just anywhere on the inland waterways.

 

Thanks

Tim

[RLWP]

Damn, I was in Leigh this morning, I did consider dropping around to see you. I could have done the driving bit

 

Richard

[Timleech]

Damn, I was in Leigh this morning, I did consider dropping around to see you. I could have done the driving bit

 

Richard

 

Boat's in Lincolnshire

(as well as needing deeper water than here for that test)!

 

You'd have got a cup of coffee, though

 

Tim

[steamraiser2]

 

I had considered that possibility, but more or less (not completely) ruled it out because

 

1) there are no apparent fuel leaks when standing. The one possible source I considered was the changeover valve on the Gardner duplex primary filter, which is at roughly the lowest point in the system and on the suction side of the lift pump. Fuel level in the tank can be above or below injector pump level, but is always above the primary filter. Feed to the primary filter is from the bottom of the tank, via a gauze duplex strainer.

 

2) when the revs drop off, there is no coughing and spluttering, it seems to be running smoothly on all cylinders.

 

I really need to arrange to watch the pump rack while someone else drives the boat and reproduces the symptoms, but it's not something that can be done just anywhere on the inland waterways.

 

Thanks

Tim

 

 

Its not a given that an air leak will show fuel. This is especially true if it is sucking through the lift pump diaphragm which is a classic Gardner issue. The hunting you describe is also typical of air in the system. Usually a duff governor on a Gardner causes over speeding not hunting. Generally they are pretty reliable unit best set up properly and then left alone.

[Timleech]

 

 

Its not a given that an air leak will show fuel. This is especially true if it is sucking through the lift pump diaphragm which is a classic Gardner issue. The hunting you describe is also typical of air in the system. Usually a duff governor on a Gardner causes over speeding not hunting. Generally they are pretty reliable unit best set up properly and then left alone.

 

As said, the lift pump was overhauled about 500 hours ago, so while that doesn't rule it out I'd think it makes it unlikely, unless perhaps the clamping screws need nipping up (I shall certainly check that one). Why would the symptoms be restricted to a narrow band of speed settings? And by setting the throttle lever for , say, 810 rpm the resultant average is more like 700, whereas setting it for 790 gives a steady 790. and 850 gives a steady 850. Reducing the load doesn't materially alter the symptoms. That's what really mystifies me, I'm not ruling out air but having difficulty rationalising how it could be the cause.

 

Tim

[Split Pin]

I would be inclined to think that it is a governor problem,

something causing the rack or the linkage to stick at a particular point.

Maybe the bearings in the end of the governor sleeve are are failing

Governor sleeve sticking on the shaft,

Main spring or thrust bearing problem

Balance weight fulcrum loose on the shaft,

End float developed in the camshaft

Most of course are quite unlikely, but investigation required to eliminate

 

Steve

[Timleech]

I would be inclined to think that it is a governor problem,

something causing the rack or the linkage to stick at a particular point.

Maybe the bearings in the end of the governor sleeve are are failing

Governor sleeve sticking on the shaft,

Main spring or thrust bearing problem

Balance weight fulcrum loose on the shaft,

End float developed in the camshaft

Most of course are quite unlikely, but investigation required to eliminate

 

Steve

 

Thanks to all for suggestions.

I suppose there's logic in having a spare lift pump to hand anyway, not something you can easily get off the shelf these days if there's a problem & then I could eliminate that possibility before digging deeper.

Do all Gardners use the same lift pump operating lever? Amal pumps for Gardners do turn up on fleabay from time to time, & I have a service kit tucked away.

Mine is driven from the valve camshaft.

 

Tim

[martyn 1]

 

Do all Gardners use the same lift pump operating lever? Amal pumps for Gardners do turn up on fleabay from time to time, & I have a service kit tucked away.

Mine is driven from the valve camshaft.

 

Physically the pump body is the same throughout the LW/LX range but they have different cam follower arms between those mounted on the cambox and those onto the crankcase. not an issue if you got the wrong one as you can swap the arm over from yours if needed.

[Timleech]

 

Physically the pump body is the same throughout the LW/LX range but they have different cam follower arms between those mounted on the cambox and those onto the crankcase. not an issue if you got the wrong one as you can swap the arm over from yours if needed.

 

Thanks, I'd guessed that would probably be the case.

I've got a pump here from something else, probably not Gardner, has a very short arm, looks almost unused but has been robbed for parts. Most missing bits are in the service kit, though I'm short of the top cover and screws.

Incidentally, does the L3B use the same body?

 

Tim

[Split Pin]

It is probably worth checking that you are getting fuel return from the lift pump via the leak of port on the engine mounted filter, there is a .018 dia hole in the filter body that is supposed to leak off any air that gets into the system before it reaches the pump inlet rail, section 41 in my service book, just something else to eliminate from the list,

 

I would have thought that you would get uneven running,rather than a reduction in rpm and hunting if the problem was directly fuel pressure related

 

I rum my 3LW on gravity feed only, when the tank is nearly empty there is only a head of about 3 inches and only about 2" of fuel above the outlet from the tank, it then has to get through 2 filters before it reaches the pump, , I dont suffer from fuel starvation even when tanking up the Trent at 800+rpm.

 

Steve

Edited September 18, 2014 by Split Pin

[Timleech]

It is probably worth checking that you are getting fuel return from the lift pump via the leak of port on the engine mounted filter, there is a .018 dia hole in the filter body that is supposed to leak off any air that gets into the system before it reaches the pump inlet rail, section 41 in my service book, just something else to eliminate from the list,

 

I would have thought that you would get uneven running,rather than a reduction in rpm and hunting if the problem was directly fuel pressure related

 

I rum my 3LW on gravity feed only, when the tank is nearly empty there is only a head of about 3 inches and only about 2" of fuel above the outlet from the tank, it then has to get through 2 filters before it reaches the pump, , I dont suffer from fuel starvation even when tanking up the Trent at 800+rpm.

 

Steve

 

Yes, I agree, especially if it's air, but I'm not ruling anything out yet.

 

I thought I was on to a winner with the spare fuel pump. As said, I have an incomplete pump which has seen little or no use. Looking through my 'old bits' shelf, found a pump which, judging by its colour, came from a 2L2 which I had about 30 years ago! The castings are fairly knackered, but it has the top plate and what is possibly the correct operating arm so should have enough bits to make a good pump. Then hit a snag - on the Gardner pumps the suction & delivery are on opposite sides of the pump, on this one with the good castings they are adjacent to one another, so no use unless I want to redo the suction pipe (which I don't!)

 

Thanks

Tim

[martyn 1]

Incidentally, does the L3B use the same body?

 

Tim

The L3 / L3B's I've worked on (if they have the pumps fitted) are the same pump, valve camshaft driven. They have mostly had two pumps fitted on each engine.

Edited September 19, 2014 by martyn 1

[jenevers]

 

 

Its not a given that an air leak will show fuel. This is especially true if it is sucking through the lift pump diaphragm which is a classic Gardner issue. The hunting you describe is also typical of air in the system. Usually a duff governor on a Gardner causes over speeding not hunting. Generally they are pretty reliable unit best set up properly and then left alone.

As a point of interest does the amal pump work while the engine is running or is it purely a priming pump to get rid of air in the system, manually?

[martyn 1]

As a point of interest does the amal pump work while the engine is running or is it purely a priming pump to get rid of air in the system, manually?

It is used for priming and also pumps while the engine is running, driven by an arm that runs off either the injector pump cambox cam or the main engine valve cam depending where it is mounted

[jenevers]

It is used for priming and also pumps while the engine is running, driven by an arm that runs off either the injector pump cambox cam or the main engine valve cam depending where it is mounted

Hmm. I'm surprised that the Amal pumps while the engine is running. Isn't the fuel pump with the individual injector levers sufficient?

 

So I guess the diaphragm in the amal pump will eventually wear out. I'm not aboard at the moment is there a drain plug on the bottom of the pump?. Also I've noticed an increase in diesel leakage around the pump. I wonder if this is anything to do with BIO addditves

Edited September 23, 2014 by jenevers

[Timleech]

So I guess the diaphragm in the amal pump will eventually wear out. I'm not aboard at the moment is there a drain plug on the bottom of the pump?. Also I've noticed an increase in diesel leakage around the pump. I wonder if this is anything to do with BIO addditves

 

There's a little removable sump, some pumps also have a coarse screw-on gauze strainer which is visible when you remove this sump.

 

Tim

[jenevers]

 

There's a little removable sump, some pumps also have a coarse screw-on gauze strainer which is visible when you remove this sump.

 

Tim

So what's the idea of the sump?

I've never read anywhere that this should be checked after a certain interval.

[Timleech]

So what's the idea of the sump?

I've never read anywhere that this should be checked after a certain interval.

 

To collect crud separated out by the gauze strainer. If you have a proper primary filter, properly maintained, in the line before the pump, there shouldn't be any but not every installation is perfect or perfectly maintained. These pumps were not only fitted to Gardners, plus Amal's main business was carburettors for petrol engines where filtration used to be scarcely bothered with.

 

Tim

[jenevers]

 

To collect crud separated out by the gauze strainer. If you have a proper primary filter, properly maintained, in the line before the pump, there shouldn't be any but not every installation is perfect or perfectly maintained. These pumps were not only fitted to Gardners, plus Amal's main business was carburettors for petrol engines where filtration used to be scarcely bothered with.

 

Tim

Thanks. I have both the Gardner in line fuel filters (with paper elements) but I'll check the Amal pump anyway. Don't suppose it's ever been drained.

It is probably worth checking that you are getting fuel return from the lift pump via the leak of port on the engine mounted filter, there is a .018 dia hole in the filter body that is supposed to leak off any air that gets into the system before it reaches the pump inlet rail, section 41 in my service book, just something else to eliminate from the list,

 

 

Where exactly is this .018 dia hole in the filter body? My service book's aboard and I'm not.

[Split Pin]

Thanks. I have both the Gardner in line fuel filters (with paper elements) but I'll check the Amal pump anyway. Don't suppose it's ever been drained.

Where exactly is this .018 dia hole in the filter body? My service book's aboard and I'm not.

 

Its between the drain back pipe tapping (the one vertically above the filter bowl) and the lift pump inlet tapping to the filter body,

 

Without any fitting in the return pipe tapping the hole should be visible, alternately disconnect the return to tank pipe and operate the lift pump, fuel should leak out of the return pipe tapping.

 

Steve