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No revs!


swift1894

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In the absence of a primary filter between the tank and the lift pump, the gauze screen was essential to stop muck getting into the pump valves and preventing them from seating properly, but if you have a primary filter before the lift pump there's no need for the gauze screen to be fitted.

 

Thanks, there is a primary filter between the tank and lift pump. But there's probably a gauze in the pump too (engine is ex Navy so I imagine it had all precautions available).

Edited by swift1894
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Some very interesting reading here, assuming your fuel system is clear and air intake is not constricted in any way it would be worth checking the valve clearances, injector pump rack and the governor settings, my guess lies with the governor.

I have driven many different Gardner powered trucks and believe me none of them produce anywhere near full power until fully warmed up of which some take much longer than others especially the 8 cylinder 240 which actually used to cool down when running empty, we used to remove the cooling fan permanently on those models and this gave an extra 12/14 BHP !!.

I used to know an old guy that ate, slept and breathed Gardner and the advice he always gave was warm up gently, work them hard and don't linger too long in stopping them.

 

 

My first post on here, so here goes,

I don't think it's a fuel starvation issue this, as the op is reporting a loss of speed control, not misfiring or stumbling when clutching in.

A 40 ton barge with a 4lw will be likely swinging a fairly large propeller through reduction gearing.

It is possible that with a cold engine,cold engine and gearbox oil, shaft drag, a big alternator all sapping power it didn't on this occasion have enough torque to pull away.

It's not easy to de-prime a Gardner

Pump quickly as the fuel volume

Chambers above the pump elements hold a fair amount of fuel.

I would check that the air release vent screw on the filter housing is clear, it's a only a tiny drilling, and that the return line is clear.

With the engine running,crack open the vent plug (s) on the pump volume chambers till fuel appears.

Was the stopping cam fully withdrawn?

This would limit fuel rack travel and rpm too.

My money's on a sluggish governor action, if it's got cold congealed oil on it's sliding surfaces inside.

Check the oil supply to the governor by quickly removing the inspection plug with the engine idling, don't put anything in or near the hole as the governor weights are revolving just inside. Just have a good look inside with a good torch.

It should be throwing drops of oil out of The plug hole, not a massive amount, but have some rags ready.

Look down into the bottom of the housing and oil should be trickling in from the cambox. There is also a feed at the back, higher up directly onto the governor weights which is quite difficult to see. There is a plug at the rear inboard side of the governor housing for this feed.replace plugs when finished.

Many years ago I drove many Gardner 6lxb engined busses, and these too were gutless in the morning.

Remember how they used to " hunt" at idle when cold, this gradually getting less as it warmed up.

Going into work at 05.30 on garage duty and starting up 30 odd clapped out Daimler fleetlines and atlanteans ready for the drivers coming in. Thick grey smoke, watering eyes, your clothes stank of unburned fuel. A blast up the road and the grey smoke went blue, then by dinnertime was gone.

Gardners offered an upgrade kit of high compression pistons for lxb's to stop them gassing people at bus stops. But we still love them!

 

You're both quite right in what you say about how all types and models of Gardners typically perform, particularly high running hours engines, when started from cold and being underworked, but the smoke, irregular running and apparent initial lack of power all result from one thing, and that's inefficient and incomplete combustion, caused by the additional compression losses when cold, mainly past the rings, over and above those which occur when warmed up, in what is already a relatively low compression ratio engine.

Add the effects of less than perfect, and possibly partially blocked, injector nozzles not fully atomizing the fuel, and you have all the ingredients for irregular running, smoke and an initial apparent lack of power. The severity and extent of all this is obviously dependent on the individual engine's mechanical condition and the condition of the fuel injection equipment, but it doesn't occur with either new or totally rebuilt Gardners in perfect 'as new' mechanical condition.

There is another design feature which is somewhat detrimental to smoke free and regular running from start up, and that is the injection timing being slightly retarded (late) at low revs in comparison with the increasing amount of injection timing advance regulated by the position of the speed control linkage which is designed and set up for optimum timing/advance when operating further up through the speed range and to maximum governed rpm with the speed control up against the maximum rpm stop.

 

From what was said in the OP, the problem with the revs not rising off idle was a first time, one off event which doesn't seem to have happened again since. It may have been a temporary interruption of fuel supply somewhere in the fuel system, or it may have been something physically preventing the governor and linkage from moving the injection pump control rack, but either way, it was undoubtedly fuel starvation.

If the cause was lack of lubrication and sticking of any part of the governor and linkage, I think it's unlikely to have cured itself and not occurred again afterwards, but it could well have been some small object, such as a loose nut, a washer, a broken split pin etc, etc, falling onto, or off, the engine and temporarily lodging somewhere in the external linkages and levers.

A temporary interruption in fuel supply could result from a bit of muck lodging in one of the lift pump valves and then clearing itself, in which case, whatever it was, it may still be in the pump waiting to get into the delivery valve and stop that from working at some very inopportune moment, or it may now be sitting harmlessly in the bottom of the 'pet' filter on the engine.

Edited by Tony Dunkley
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Tony is quite right, poor combustion could be a factor too.

But I'm only going off what we know so far, loss of speed control.

We need more detail to make in informed diagnosis on this. Too many variables.

It would be useful to know if,

Before casting off, the engine was idling normally,no excessive white or grey smoke, misfiring or erratic idling.not that you would do such a thing!

When clutching in, did the idle speed drop and then recover in the normal way,due to the governor action?

Does it have single lever control?

Could be something amiss there.

We need to eliminate the possibilities one by one.

Prove the fuel supply is adequate.

Prove the oil feeds to the governor,and that its action is free and smooth.

Prove that the fuel rack,quadrants,links,pivots etc are all freely moving.

A Gardner engine in fine fettle is a joy to behold and will do all that Is asked of it economically and reliably. But they are not infallible.

Beloved of tight arsed haulage operators and bus companies gardners have an amazing ability to keep plodding on year in year out with but little maintaince,while totally clapped out.

But, like any engine, can be a box of frogs if badly neglected.

Half a day spent going over the points others and myself have raised

Is time well spent,and brings confidence in the engine.

Gardners are an interesting engine to work on,beautifully over engineered,almost regardless of cost.

Take an interest in it, show it some tlc, you've got a friend for life there.

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