Lister Alpha 4 mystery

[miles beyond]

Hard to start - need to leave preheaters on for a long time - 1 min plus and then not always at first attempt.

 

Compression is good at 400psi

 

Plugs all tested and working.

 

Circuit to plugs working properly.

 

Manual stop fully closed.

 

New injectors.

 

Anyone got any other ideas as to why this might be so hard to get to fire up. Once running it goes a treat.

 

Thanks.

[chris w]

Have you checked for good fuel flow after the fuel pump and at the injectors?

 

Chris

[John Orentas]

Heater plugs carboned up, take them out, clean up the plugs and orifices. Lots of white smoke/ unburned fuel wilst cranking?

[miles beyond]

Have you checked for good fuel flow after the fuel pump and at the injectors?

 

Chris

 

Yup. No supply problem.

 

Heater plugs carboned up, take them out, clean up the plugs and orifices. Lots of white smoke/ unburned fuel wilst cranking?

 

I've had them out, tested, and they are fine.

 

Yes, plenty of white smoke/unburned fuel when cranking.

 

According to the previous owner it was just as much of a pig at ony 850 hours.

 

One suggestion has been that perhaps it was assembled with one of the timing gears a tooth out. Unfortunately the people who fitted out the boat built round te engine (how unusual I hear you think!) and to get at the gears involves major destructive work to a bulkhead.

 

Hmmmmm

[Canal Shop Man]

 

I've had them out, tested, and they are fine.

 

 

I also suspect carbon around the heater plug holes as suggested by John- this was a regular problem with a BMC 1500 I used to have. It needs a drill just smaller than the thread size twisted by hand in the plug hole - just don't let go so it falls in (I used to put a bit if tape round the end of the drill bit so it couldn't go right in even if I let go)

 

I have the same problem with my Lister LPWS2 which is a very similar engine to yours - please let us know how you sort it. I have just bought new injectors (at 3000 hrs), having got a manual which recommends changing them at 2000 hrs!

[Yoda]

Is it trying to start backwards?

[Tony Brooks]

Hard to start - need to leave preheaters on for a long time - 1 min plus and then not always at first attempt.

 

Compression is good at 400psi

 

Plugs all tested and working.

 

Circuit to plugs working properly.

 

Manual stop fully closed.

 

New injectors.

 

Anyone got any other ideas as to why this might be so hard to get to fire up. Once running it goes a treat.

 

Thanks.

 

 

Is this one of the Listers with hydraulic valve lifters?

 

Although the 400 PSI woudl typically indicate a glowplug or injector spray pattern fault (and not what I am going to say) it is becoming increasingly apparent that the Listers with the hydraulic valve lifters are prone to bad starting caused by low oil pressure during cranking (the valves do not open properly). once running and whilst warm they are fine.

 

So if you managed to start the engien and then did the compression test may I suggets a cold cranking oil prressure test. If it is low I fear the oil pumps are a bit suspect.

 

 

Tony Brooks

[miles beyond]

I also suspect carbon around the heater plug holes as suggested by John- this was a regular problem with a BMC 1500 I used to have. It needs a drill just smaller than the thread size twisted by hand in the plug hole - just don't let go so it falls in (I used to put a bit if tape round the end of the drill bit so it couldn't go right in even if I let go)

 

I have the same problem with my Lister LPWS2 which is a very similar engine to yours - please let us know how you sort it. I have just bought new injectors (at 3000 hrs), having got a manual which recommends changing them at 2000 hrs!

 

Thanks - food for thought.

 

 

Is it trying to start backwards?

 

Er, no! I'm intrigued by this idea.

 

Is this one of the Listers with hydraulic valve lifters?

 

Although the 400 PSI woudl typically indicate a glowplug or injector spray pattern fault (and not what I am going to say) it is becoming increasingly apparent that the Listers with the hydraulic valve lifters are prone to bad starting caused by low oil pressure during cranking (the valves do not open properly). once running and whilst warm they are fine.

 

So if you managed to start the engien and then did the compression test may I suggets a cold cranking oil prressure test. If it is low I fear the oil pumps are a bit suspect.

Tony Brooks

 

Thanks very much for this. I was under the impression that 400PSI meant it was good and healthy on the compression front. Can you elaborate for me? I would be very grateful.

[Tony Brooks]

Thanks - food for thought.

Er, no! I'm intrigued by this idea.

Thanks very much for this. I was under the impression that 400PSI meant it was good and healthy on the compression front. Can you elaborate for me? I would be very grateful.

 

 

Taking quoted compression pressures from a variety of published engines with indirect injection (glow plug engines) a bit over 400 psi (say 436) is probably absolutely fine.

 

However only in the case of Listers with hydraulic valve lifters if that reading was obtained with a warm/hot engine it might be beter to try again with it stone cold because if it is suffreimng from low cold cranking oil pressure a warm/hot compression test might give good results, but a cold one may give a far lower reading.

 

Unfortunatley I have not had the opportunity to compression test one of these engines with low oil pressure so excatly what effect it will have on compression pressure I am not sure, but I do know there is a problem with cold starting these engines when the oil pump or other things wear.

 

Best test the OIL PRESSURE during cold cranking and compare with Lister's figure.

[John Orentas]

I am confused here, when I was learning about these things 300 psi was considered about right for a diesel engine.

The typical compression of 20:1

Atmospheric pressure 14.5 psi

19 x 14.5 = 290

 

So a modern small diesel normally aspirated engine should produce a pressure of typically 300 psi. Where does the 400 psi come from.

Edited November 27, 2006 by John Orentas

[miles beyond]

Taking quoted compression pressures from a variety of published engines with indirect injection (glow plug engines) a bit over 400 psi (say 436) is probably absolutely fine.

 

However only in the case of Listers with hydraulic valve lifters if that reading was obtained with a warm/hot engine it might be beter to try again with it stone cold because if it is suffreimng from low cold cranking oil pressure a warm/hot compression test might give good results, but a cold one may give a far lower reading.

 

Unfortunatley I have not had the opportunity to compression test one of these engines with low oil pressure so excatly what effect it will have on compression pressure I am not sure, but I do know there is a problem with cold starting these engines when the oil pump or other things wear.

 

Best test the OIL PRESSURE during cold cranking and compare with Lister's figure.

 

Thanks again. I'll put this t'committee and let you know if it is the solution.

 

I am confused here, when I was learning about these things 300 psi was considered about right for a diesel engine.

The typical compression of 20:1

Atmospheric pressure 14.5 psi

19 x 14.5 = 290

 

So a modern small diesel normally aspirated engine should produce a pressure of typically 300 psi. Where does the 400 psi come from.

 

It comes from the compression test my local friendly marine engineer carried out a few weeks ago. He says that is about right and if it was as low as 290 psi then there would be a problem.

[John Orentas]

It comes from the compression test my local friendly marine engineer carried out a few weeks ago. He says that is about right and if it was as low as 290 psi then there would be a problem.

 

 

Fair enough but is someone going to show where my sums are wrong.

 

20 x 14.5 = 290 psi

[Sir Nibble]

Fair enough but is someone going to show where my sums are wrong.

 

20 x 14.5 = 290 psi

 

You forgot to add the effect of the large amount of heat generated by the compression. Boyles law?

[Yoda]

Fair enough but is someone going to show where my sums are wrong.

 

20 x 14.5 = 290 psi

 

You forgot to add the effect of the large amount of heat generated by the compression. Boyles law?

 

No don't go there. A cranking compression ratio that generates about 300 psi is a minimum for diesel type engine

[John Orentas]

No don't go there. A cranking compression ratio that generates about 300 psi is a minimum for diesel type engine

 

 

What do you mean don't go there, it is simple arithmetic. I am not certain but will the heating effect at very low speed add 100 psi

[Yoda]

What do you mean don't go there, it is simple arithmetic. I am not certain but will the heating effect at very low speed add 100 psi

 

Running compression does not mean anything unless something drastic has happened. Cranking compression is key as this enables the engine to start/run in the first place. You are not interested in the burn pressure in the cylinder.

[John Orentas]

Running compression does not mean anything unless something drastic has happened. Cranking compression is key as this enables the engine to start/run in the first place. You are not interested in the burn pressure in the cylinder.

 

 

I'll try again, it was you who brought up the heating. Turning an engine slowly by hand, if the compression ratio is 20 : 1 you will get a pressure 20 times atmospheric hence 20 x 14.5 = 290psi. However the compression itself will generate heat. Without any burning the temperature will reach many hundreds of degrees (that is what ignites the fuel if there is any).

 

That temperature increase of the air in the cylinder will further increase the pressure, but will it increase it to an extra 100 psi to bring it to Tony's 400+ psi figure.

 

Just thinking aloud.

[chris w]

Strictly, speaking the answer is not contained within Boyle's law per se but the "Combined Gas Law":

 

viz: ( P1 x V1)/T1 = (P2 X V2)/T2

 

which with the addition of Avogadro's law gives:

 

PV = nRT

 

where

 

P is the pressure in pascals

V is the volume in cubic metres

n is the number of moles of gas

R is the ideal gas constant (8.3145 J/(mol K))

T is the temperature in kelvins.

 

From which the additional pressure due to the temperature rise may be calculated

 

Chris

[Yoda]

Told you not to go there!!!!!

[Canal Shop Man]

OOhhhhhhhhh - my brain hurts!

 

PS Can you count the moles as they come out the exhaust? Do the moles in the gas cause it not to fire up??

 

PPS It's a Lister, not a Kelvin . . .

Edited November 27, 2006 by Canal Shop Man

[Tony Brooks]

Just been on the Dutch engine manual site to recheck the figure I gave (link from my site - www.tb-training.co.uk). Not all manufactures publish a compression figure, but Mitsubishi do ( Vetus) and they give two figures. On engine has just over 500psi and another 470 @ 280 rpm. I think the 436 came from Peugot data.

 

 

Remember that a direct injected die4sel (no glowplugs) is likley to have a compression ratio between 13 & 15:1 whilst an indirect diesel typically uses arround 23:1 (Mitsubishi) quote 25:1 on one of their engines.

 

Of course these figures are for engines in good order and I am sure 400psi will be fine, but we must remember that the indirect injected diesel looses heat to a lot of steel and water whilst cold starting (hence the glowplugs) without much help from friction through the pre-combustion chamber throat. This is one reason indirect injected engines (in the main) have such high compression ratios.

 

I hope we will eventually be told the diagnosis on this particular engine.

 

Tony Brooks

[Yoda]

 

Of course these figures are for engines in good order and I am sure 400psi will be fine, but we must remember that the indirect injected diesel looses heat to a lot of steel and water whilst cold starting (hence the glowplugs) without much help from friction through the pre-combustion chamber throat. This is one reason indirect injected engines (in the main) have such high compression ratios.

 

Tony Brooks

 

Are you sure that you have the explanation in the correct order?

[chris w]

There's obviously a mole in t'ole!!

[Tony Brooks]

Are you sure that you have the explanation in the correct order?

 

 

Yes - about 90% certain, but you will always find an oddball engine.

 

An old BMC 6 pot direct injected about 13.5:1 from memory, Buck DV26 (direct injected) 18.5:1 from manual.

 

Now I know why my DV36 is such a good cold starter!

 

This is also why glow plug engines tend to have heavier flywheels - to smooth the lumpiness from the extra compression at low speed.

 

I am 100% certain that the bit about heat loss is correct.

 

Anyway, all I was trying to do was to get the thread away from sums and science and back to more practical things. Also trying to point interested parties to those online engine manuals.

 

 

 

Tony Brooks

 

Tony Brooks

[miles beyond]

Just been on the Dutch engine manual site to recheck the figure I gave (link from my site - www.tb-training.co.uk). Not all manufactures publish a compression figure, but Mitsubishi do ( Vetus) and they give two figures. On engine has just over 500psi and another 470 @ 280 rpm. I think the 436 came from Peugot data.

Remember that a direct injected die4sel (no glowplugs) is likley to have a compression ratio between 13 & 15:1 whilst an indirect diesel typically uses arround 23:1 (Mitsubishi) quote 25:1 on one of their engines.

 

Of course these figures are for engines in good order and I am sure 400psi will be fine, but we must remember that the indirect injected diesel looses heat to a lot of steel and water whilst cold starting (hence the glowplugs) without much help from friction through the pre-combustion chamber throat. This is one reason indirect injected engines (in the main) have such high compression ratios.

 

I hope we will eventually be told the diagnosis on this particular engine.

 

Tony Brooks

 

Lister unfurunately do not publish their compression figures.

 

Of course I will let you know how the patient progresses - it would be very churlish and rude not to!

 

Strictly, speaking the answer is not contained within Boyle's law per se but the "Combined Gas Law":

 

viz: ( P1 x V1)/T1 = (P2 X V2)/T2

 

which with the addition of Avogadro's law gives:

 

PV = nRT

 

where

 

P is the pressure in pascals

V is the volume in cubic metres

n is the number of moles of gas

R is the ideal gas constant (8.3145 J/(mol K))

T is the temperature in kelvins.

 

From which the additional pressure due to the temperature rise may be calculated

 

Chris

 

I bet you're dead handy at crosswords too!