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Author Topic: Lister JP3 knocking advice!  (Read 6426 times)

bertie76

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Lister JP3 knocking advice!
« on: June 09, 2011, 12:32:47 AM »
???Hello all. I am having trouble diagnosing a knocking in my JP3 and have tried various approaches. The knocking is definately related to the crankshaft (one knock per revolution) and gets worse as the engine warms up (leading me to suspect piston to valve/head contact, which inspection reveals was not happening).
The sound is difficult to identify and is a light knocking and not a heavy thudding. I've had injectors tested, replaced the injector pump, reground all valve seats (during a decoke), and fitted new exhaust guides//valves.
Listening to all the U tube footage of JP3s, it seeems that most of the old ones have this noise, though I have personally seen JP3s that run sweet as a nut and do not suffer the same.
I have replaced the bevel gears driving the injection pump and am happy that the noise is not coming from there.
Endplay on the main bearing is about 4 thou and does not seem excessive; big end fore and aft play about 15 thou and equal on all bearings (there's no up and down slack); gudgeon pins/bushes all tight.
I do have worn liners (Listard missing from a 2 inch patch at top ring TDC on one cylinder, with slight pitting to the cast iron) and the piston seems very loose in the bore - could this be piston slap??? Strange how it seems to get worse with heating up.
All comments welcome and any advice on whether it's worth pulling a liner or is it opening a can of worms, ie, difficult and likely to result in problems sealing the liner in a corroded engine? Regards, bertie.
ps, does anyone know of a source of new old stock pistons and rings????

dieselgman

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Re: Lister JP3 knocking advice!
« Reply #1 on: June 09, 2011, 12:44:05 AM »
Check Sleeman & Hawken and also MEAD Plant for NOS spares... If they can't find it, likely not available at all. We do not have experience with the JP3 but could offer the general ideas from experience with other Lister models. What kind of oil pressure is your engine running cold/hot? Have you tried dropping out the injector pressure on that problem cylinder to see if it is piston or ignition knock?

dieselgman
ALL Things Lister/Petter - Americas
Lyons Kansas warehousing and rebuild operations

dieselgman

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Re: Lister JP3 knocking advice!
« Reply #2 on: June 09, 2011, 12:48:45 AM »
Bertie,

Have you measured actual clearance on the problem cylinder? How far it varies from spec may help you decide if that noise (and further degradation of performance) is tolerable - or financially viable to repair.

dieselgman
ALL Things Lister/Petter - Americas
Lyons Kansas warehousing and rebuild operations

bertie76

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Re: Lister JP3 knocking advice!
« Reply #3 on: June 11, 2011, 02:26:07 PM »
Hello Dieselgman, Thanks for the posting. Clearances were all set the same on the heads on reassembly last time and were equal, though I shall be doubly careful on next reassembly. Have measured the wear on pistons (35 thou at top, 27 recommended; 20 thou at base, 7 recommended), liners (10 thou, 2 recommended), and big ends (going to fit new shells). Looking at the governor weights, it seems that the weights have been knocking against the camshaft bevel gear inside, as the travel of the camshft thrust bearing was too great - not sure if this would create a cyclical knock though.
How can one reduce the injection pressure on the problem cylinder (other than unscrewing the feed pipe)? Do you mean adjusting the nozzle set point, currently at 150bar?
Keep the comments coming.
Regards, Bertie.

dieselgman

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Re: Lister JP3 knocking advice!
« Reply #4 on: June 11, 2011, 04:51:13 PM »
To isolate a knocking piston, (either from excessive wear or from wrong injection timing) it is possible to crack open the injector supply line while the unit is running. If the knock goes away at that point, then you can be pretty sure which cylinder is causing the noise and also a bit more about top-end vs. bottom as a source point. We often use this method to compare power output in multi-cylinder engines and also quickly isolate a problem cylinder. Unfortunately, we have no specific experience with the JP3 and its quirks.

dieselgman
ALL Things Lister/Petter - Americas
Lyons Kansas warehousing and rebuild operations

listard-jp2

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Re: Lister JP3 knocking advice!
« Reply #5 on: June 17, 2011, 01:44:36 PM »


I do have worn liners (Listard missing from a 2 inch patch at top ring TDC on one cylinder, with slight pitting to the cast iron) and the piston seems very loose in the bore - could this be piston slap??? Strange how it seems to get worse with heating up.
All comments welcome and any advice on whether it's worth pulling a liner or is it opening a can of worms, ie, difficult and likely to result in problems sealing the liner in a corroded engine? Regards, bertie.
ps, does anyone know of a source of new old stock pistons and rings????

It sounds like you have all the signs of piston slap.

If you have worn through the chrome plating, then that's not a good situation to be in, as it will only get worse, and the chrome particles will only cause wear in other locations on the engine, especially if you don't have an oil filter on your JP3 (which most didn't have).

If Sleeman and hawkens price is too rich for your taste, then I have some NOS genuine chrome plated liners available, if interested send me  PM.

bertie76

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Re: Lister JP3 knocking advice!
« Reply #6 on: June 19, 2011, 11:08:08 PM »
Hello Listard-2
Thanks for the advice (and the valuable advice that you have previously given me!!).
New liners are in and not leaking yet  ;D. New Indian pistons resplendent with new rings  ;D.
Next stop are new main bearings - any advice on fitting these, as they look like they'll need a little pressing into the recesses?
Rgds, Bert.