question Matador 7.7engine starting from cold

[Ed Batchelor]

My Matador starts instantly even when left for extended periods of time, however the throttle response is very poor to begin with, fully pressing the throttle does not result in an increase in revs and the whole thing seems pretty asthmatic. One left to tick-over for a few minutes it will pick-up with more and more throttle response until it revs more freely.

I havent really investigated this, I wonder if it is to do with the governor weights being a bit sticky in the pump. I did fill the oil levels in both parts of the pump to the correct level, however the governor was missing one of the inspection plates when I got it (now re-fitted). Maybe an amount of diesel in there would help matters by freeing off any offending components? When warmed up it responds fine.

Fuel and air issues I would have thought would remain an issue whether warm or not.

Any ideas suggestions from Matador experts (or non - experts!) welcomed.

[philb]

There's a funny thing, mine sometimes does that.

I doubt if it is the governor sticking because the rack is probably going up against the maximum fuel stop to get it started so easily - it won't be sticking in that position or the engine would go wild. So, I'll guess it is governing around the right idle speed once it's running.

I think the problem with mine is that air is getting into the gallery somehow. Like yours it will start instantly (from the fuel left in the pump elements) but won't rev up and it makes a lot of grey smoke for a minute or so before it runs properly. It's not just because it is cold - usually however cold it will start easily and run up straight away.

If/when you find out what's wrong, do let us know.

[Ed Batchelor]

Mine fires up and goes straight to tick over, a very low tick over. It doesnt rev up, I know the inline simms pumps on fordson engines can get sticky over time and result in erratic running. I wondered whether the pump was a bit sticky, until oil get splashed up round either the rack or the governor and works itself free. I dont think heat has anything to do with it (I was using warmed up as an expression) since the pump casing does not warm up that fast!

Once running OK I dont get any more symptoms unless left parked up again.

[antarmike]

May be barking up the wrong tree but on a Garner for example the engine governors work over the whole range so that a constant engine speed is achieved for a given pedal depression, regardless of the load on the engine.

 

The Matador governor on the gun tractor is described as a Maximum and minimum speed governor.

 

Only the ACV with an engine driven generator had a constant speed governor that worked to maintain constant engine speed even when load on generator is varying.

 

As such the normal Matador governor is only really working when max speed is approached when the governor comes into action to prevent overspeeding, or when minimum speed is approached to prevent stalling, mid range in effect the throttle is working in effect directly onto the rack. (ie ungoverned in normal driving. This is why the Matador is so responsive and you can blip the throttle on a 7.7 in a way you can't on a Gardner. (and why an AEC is far less fuel efficient than a Gardner!!!)

 

If this analysis is correct then it is unlikely that the slow response when first started is due to sticking governor. More likely it is just a cold engine not burning the fuel that well. My Matador wouldn't pull well until I had driven two or three miles. for the first few miles a hill that a hot engine would take in fourth, needed third gear to climb.

 

Difficulty in getting responsive throttle control from startup, is in my opinion a characteristic of the engine, and not a fault.

 

Discuss.

[Mattyboy]

My comments for what they are worth, disconnect the fuel pipe that feeds the pump, ie the pipe from the lift pump to the pump. Make sure that if the pump has the internal in line filter it is clean. Then using a empty coke bottle with the bottom cut off, hang this in the cab then run a pipe to the pump. Undo the bleed screw on the back of the pump (the now gravity fed system) will purge the air. Start the engine, if it runs fine and the problem goes, stop the engine and leave for a few hours, a day etc. Then re-start it again (don't bleed it) This will then rule out the fuel system issues. Also check the air intake pipe/ filter, if it can't get enough air it will never run right.

[philb]

As you say Mike, a cold engine (and drive chain) will sap power until the oil warms up and cold combustion chambers will cause poor combustion reducing the power further. However, if everything is in good order (and it probably is if the engine starts so easily) it should still have plenty of power to run up to maximum governed speed off load.

 

Generator and compressor engines, for example, of the age we are talking about would run straight up to working speed but the loads would (should) not be applied until they had warmed up.

 

If Ed's engine doesn't have the power to spin up cold, I wouldn't have thought it would be happy idling either.

 

Ed, does the engine smoke heavily when it's in this lazy state?

 

Regarding fuel consumption, you may well be right Mike that the min/max governor behaviour doesn't help matters but the overall consumption, under equivalent conditions, is probably down to engine design. From my book "The Modern Diesel", by Donald H Smith, 13th edition of 1959, the specific fuel consumption of the AEC 7.7 DI and the 9.6 is about 0.38 lbs/bhp/hour, whereas the Gardners are under 0.35 lbs/bhp/hour. The later 6LX of 1958 gets that below 0.34. I don't think modern engines do much better than that.

 

Maybe it's a combination of efficiency and the different torque/speed characteristics that give rise to a markedly different actual fuel consumption?

[Ed Batchelor]

Interesting comments, I dont think it smokes heavily, but it does smoke a bit from cold (not blue) tickover is very slow initially but even fully pressing the accelerator results in no response from the engine. The engine barely does half a turn before it away, but old fordson majors are the same even the most worn out ones, I have heard matadors exhibit the same good starting characteristic regardless of condition (up to a point).

Given that it is not under any load at this point it ought to race up to high idle with full accelerator. It starts to pick up after 30secs to a minute before full revs can be achieved. After that no probs.

I suspect it may be quite coked up inside, does blow a few sparks out when hot and under a bit of load.

It is worth noting that there is no exhaust fitted, just the downpipe. Engines do need an amount of backpressure to perform correctly but I dont think this is causing the issue here.

A lot of people are not aware of the max/min and all speed governors fitted to engines in different applications.

I really need to do a bit of investagative work when I find time, I was hoping it may have been a common Matador ailment but apparently not!

[Ed Batchelor]

Just to re-iterate it performs fine once running for a short while (similar to Antar Mikes comment) but initially it literally has nothing in it at all! I have towed Dads Highwayman which is just over 8ton all up, with the high ratio diff it struggled a bit in top but sat in 3rd up to 30mph no probs. Doesnt miss a beat and sounds very smooth when on song.

[philb]

Ed, if you've got the time and the inclination it might be interesting/useful to try the following:

 

Once the engine has warmed up, unscrew and remove the control rack stop from the front of the pump (the multi-holed cylinder just behind the bleed screw). The end of the rack will be exposed and with the engine idling you can mark it with a felt-tip pen to know where it should settle.

 

Then when it's been left to rest for long enough to give the trouble, get someone else to start it while you watch the rack movement. If when the accelerator is pressed the rack does not poke out much more than it did when hot and idling, something is stuck. If the rack has moved out and there's no air in the system it must (almost certainly) be fully fuelling. If it is fully fuelling and the fuel is not being burnt thoroughly enough to give you power it would almost certainly generate lots of acrid grey smoke (lots of vaporised but un-burnt fuel).

 

Another thing to try is, when in its slow idle state, pulling the rack out by hand. The engine speed should rise readily and you will feel the governor fighting you.

 

Starting the engine with the rack stop removed should give a few good puffs of dense black smoke because it will over-fuel until the governor takes over. It wont hurt anything just to try it a few times.

 

Going back to Mike's comments about fuel consumption, I believe that the Gardners of that period only had a compression ratio of 13:1 compared with 16:1 for the AEC engines. so. it's even more interesting that the Gardners achieved better fuel efficiency. They did have quite different combustion chamber designs, perhaps that's the rather obvious clue? I imagine this topic has been done to death by mechanical engineering students in the last sixty years, does anyone know of any web-accessible documents describing it?

[Ed Batchelor]

Success! Spent this morning looking at the Matador, after a few blind alleys - checking fuel supply, no air, (good fuel) oil levels in pump& governor OK (added a bit of diesel to help free anything off) but no joy. Engine very underpowered and not revving freely. Not smoking either, so ruled out injector trouble. Seemed to run evenly. Checked air filter, no problem there. Checked the built in valve in the intake (think it is something to do with cold start device) this was not shutting.

Then started looking at the throttle linkage, I realised that at full pedal travel there was still some travel on the control linkage at the pump. There is a threaded rod near the rear right of the block, the lock nuts were loose on this although the rod itself wasnt particularly loose. Shortening this rod gave full throttle at the pump. Now a different machine, revs freely, pulls in higher gears than it used to and generally performs 10x better than before. Having never really used it much I hadnt realised how underpowered it was.

Thanks for all the input, I'm sure you'll be glad to hear its now sorted!