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Author Topic: New pistons Petter PJ2, block after short time engine running. Clearance?  (Read 2641 times)

38ac

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Re: New pistons Petter PJ2, block after short time engine running. Clearance?
« Reply #15 on: October 19, 2018, 09:54:32 AM »
Thought I should add that "genuine" Lister Petter parts does not mean what it once did. The current owners of that mark are sourcing parts from India along with selling old stocks. They claim higher standards are applied but I have two experiences that dictate otherwise.
Collector and horder of about anything diesel

glort

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Re: New pistons Petter PJ2, block after short time engine running. Clearance?
« Reply #16 on: October 19, 2018, 09:59:31 AM »
Thought I should add that "genuine" Lister Petter parts does not mean what it once did. The current owners of that mark are sourcing parts from India along with selling old stocks. They claim higher standards are applied but I have two experiences that dictate otherwise.

So often the way now.  So many things come from the cheapest source and are simply re branded and marked up for manufacturers while the no names sell the exact same thing and are labeled Chinese crap because they are sold cheaper.
 

38ac

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Re: New pistons Petter PJ2, block after short time engine running. Clearance?
« Reply #17 on: October 19, 2018, 10:59:41 AM »
It is not hard to understand why the parts are currently being out sourced if one is aware of the former pricing structure. Prices were not simply high, they were totally insane and a lot of L-P engines were scrapped because of it.  Dont get me wrong, I applaud the effort to supply parts at a reasonable cost which seems to require sourcing said parts from the 3rd world.  I just dont like the fact they hide behind the legendary L-P quality while stuffing green and red boxes with parts made in India with (seemingly) no more quality control than any other supplier.
Collector and horder of about anything diesel

glort

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Re: New pistons Petter PJ2, block after short time engine running. Clearance?
« Reply #18 on: October 19, 2018, 11:52:01 AM »

Here in Oz they are selling Chinese knockoff generators and I think it was pumps with the LP branding and painted green.

They are about as LP as I am but they are still priced to kill especially when the next ad down on fleabay is the same thing in another colour and 1/3rd the cost. They may not be bad units but they sure as hell are not anything other than the typical Chinese clone unit.

Having some experience with the things, I consider them the entry level machine.  The horizontal Cyl Chinese engines IMHO are superior and then you go to the proper Jap engines like yanmar and Kubota and the euros like Ruggerini, Lombardi and others.  I can't split them but the base Chinese engines to me are only better than the Crap petrol engines like Briggs and Tecumseh.
Kawasaki, Subaru/ Robin, Yamaha and of course Honda all are vastly better than the other 2. Most of them do diesels as well but I have not had my hands on any as yet.

glort

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Re: New pistons Petter PJ2, block after short time engine running. Clearance?
« Reply #19 on: October 19, 2018, 12:16:05 PM »


Just came across this Vid which explains how to do rings gaps which may be helpful for new engine builders.

https://www.youtube.com/watch?v=gs0Fg3tvhoc

Rob PetterPJ2

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Re: New pistons Petter PJ2, block after short time engine running. Clearance?
« Reply #20 on: October 19, 2018, 01:16:14 PM »
Dear Glort and 38ac,

when I noticed the difference in the height reached by the pistons, I went to search for the cause and measured all details of the cylinders and the pistons, over and over again, and then there was not other conclusion to draw than the piston rods, or maybe the way they're attached to the crankshaft made the difference. I really didn't feel like going into the block, to avoid "fixing a thing that isn't broken", when I saw, with the shims I could adjust it. It may not have been a 1mm difference but 0,6mm, btw. Sorry for that. Taking shims away from one cylinder and adding them to the other doubles the effect. The measure for the bump clearance I copied from a manual of an almost equal Lister engine. The same for the inlet and exhaust valves.
I've just contacted the Petter specialist Jim Perkins in the UK for a manual of this engine, that he says he has.

For me, "taking the engine to a company that will fix it" is not an option. It's 300 lb and it sits in the boat. I have to be careful with my spending, it's a hobby to change this 10 meter life boat into a holiday home, do all the carpenting myself, and try do it all with that old engine still in it. I've made great trips, of months, had great party's on board, but if the fixing of the engine is going to cost a lot, I'd rather get me second hand more modern one that's a bit more sophisticated. This one doesn't even has anything to attach a start engine to and cranking it, to start it, is that heavy (a guy taller and stronger than me could just do it, and be exhausted after), that I made a construction with a scooter's engine doing the cranking, to get the flywheel turning with the speed needed to let the decompression handles go. Though that may seem complicated, it starts the Petter within 6 seconds.

Next monday I'll take the thing apart again, and follow all you guys' instructions and tips. And I may have the proper instruction book in my hands as well.

Thanks all so far!
Cheers,
Rob

Rob PetterPJ2

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Re: New pistons Petter PJ2, block after short time engine running. Clearance?
« Reply #21 on: October 19, 2018, 01:26:31 PM »
Hey Rob, When you fitted the new pistons did you fit new small end bushes (wrist pin bushes in the USA)? generally these are made of bronze and are pressed into place. They require reaming afterwards. If the machine shop reamed these out of square the piston will bind at the top one side and at the bottom on the other. When you checked the bump stop did you use two identical length pieces of lead, one either side of the piston above the gudgeon pin. The two pieces should measure the same thickness after performing the bump. If they do not then the bush is out of square.

Bob

Hi Bob
no I didn't do any of that. The engine sits in a boat. Since the pins of the pistons were such a tight fit, I didn't suspect anything worn out, there. It's me who removed the cylinders and the pistons (hammered the pin out with a wooden same size 'pin' in between). I brought them to the engine shop, and had them find and order the new pistons, hone the cylinders, after which I picked them up and did the reassembling.

Rob PetterPJ2

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Re: New pistons Petter PJ2, block after short time engine running. Clearance?
« Reply #22 on: October 19, 2018, 01:35:19 PM »


Just came across this Vid which explains how to do rings gaps which may be helpful for new engine builders.

https://www.youtube.com/watch?v=gs0Fg3tvhoc

That's a video about fire arms, Glort!

glort

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Re: New pistons Petter PJ2, block after short time engine running. Clearance?
« Reply #23 on: October 19, 2018, 02:19:59 PM »

Ah, so it is!
Great Vid though! I'll take a Dozen of each of those and a crate of ammo to go with them!  :0)

The more mundane but appropriate vid is here:

https://www.youtube.com/watch?v=_gyv-xtG51M


dieselgman

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Re: New pistons Petter PJ2, block after short time engine running. Clearance?
« Reply #24 on: October 19, 2018, 06:00:30 PM »
PJ1 and PJ2 ring end gap  .029 to .037 inch
bump clearance .036 to .042
bore 3.8175 to 3.8185 inch

dieselgman
Ford Powerstroke, Caterpillar 3304, Cummins M11, Too many Listers to count...

glort

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Re: New pistons Petter PJ2, block after short time engine running. Clearance?
« Reply #25 on: October 20, 2018, 02:12:52 AM »

Pretty wide gap! Almost 1mm at the far end.
If the rings were tight, this would certainly explain the Seizing. More expansion there than I would have given credit for especially in that size bore which isn't even 4".

  I'll be the piston clearances are pretty generous as well.  Hopefully the gaps weren't installed on the thrust side of the bore otherwise there will be scoring for sure.

Rob PetterPJ2

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Re: New pistons Petter PJ2, block after short time engine running. Clearance?
« Reply #26 on: October 21, 2018, 08:39:50 PM »
PJ1 and PJ2 ring end gap  .029 to .037 inch
bump clearance .036 to .042
bore 3.8175 to 3.8185 inch

dieselgman

Thanks, dieselgman, for these exact numbers!
I'm happy to see that the present bump clearance of my PJ2 engine is exactly in the middle of the two numbers you gave.
Coming tuesday I'll have the time to check the rest.
Cheers,
Rob

glort

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Re: New pistons Petter PJ2, block after short time engine running. Clearance?
« Reply #27 on: October 22, 2018, 12:25:10 AM »

Will be interesting to hear what you find!

ajaffa1

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Re: New pistons Petter PJ2, block after short time engine running. Clearance?
« Reply #28 on: October 22, 2018, 09:56:56 AM »
Hey Rob, Glort is right as usual ( I hate him,  :laugh: ). There is a chance of scoring in the bores, it is very unlikely to be severe. Do you have a cylinder honing tool? They are not expensive and can usually be purchased at you local automart or tool store. They fit into an electric drill, give the cylinders a quick hone to remove any scoring/high spots. Then wash out any residue with soap and water, please be diligent in doing this as metal particles and carborundum have no place in a cylinder or engine.

Adjust the ring gap and reassemble, all should be good. Recommend using flushing oil when doing the first oil change, I also recommend that you do the first oil change at half the running time stated in the manual.

Bob

glort

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Re: New pistons Petter PJ2, block after short time engine running. Clearance?
« Reply #29 on: October 22, 2018, 10:36:21 AM »

Lucky you can take the barrels off this engine. If you couldn't it would have to come out to clean it after you honed it because there would be no way to get all the grit out of the sump in a boat. If you se a line ( or several) run your fingernail across them and see if you can feel them.  If you can, will definitely need a hone, if you can't.... probably OK.  I used to run 2 strokes with all kinds of marked bores and they were fine. The speed they run at means there is not much time for blow by and other things and they are a bit inefficient anyway in their gas flows but there is an awful lot you can get away with in 2 strokes that diesels are probably more particular with.

More I think about this the more I think Bob nailed it.  If the engine shop sourced the pistons and did the bores, they would set the clearances to match unless they really stuffed up. It would be automatically assumed that the person assembling the engine would check and set the rings gaps.
Kinda why it slipped my mind, it would never occur to me that they would be put in without checking.  Bit like putting a head on without a gasket.

Given the gaps are so wide on these engines, it's almost an odds on bet they would be way too tight from the factory, the fact the engine locks up so quick makes sense it would be the rings because they would heat up first from the friction alone and as soon as the piston swelled.  Ouch!

How many times have you run the thing when it locked up? Was it ever under load or making any power as in above idle?
Locking up an engine like that is a mechanical cringe fest.  Hopefully nothing bad has happened.

When you take the thing apart, I would try to lift the cylinders just enough to stuff rag over the top of the block so nothing can fall in the sump before you liberate the piston from the bore.   It's possible you may have snapped a ring which would  still likley be in place given the tight clearances ( you'd sure want to hope it is!) but may drop out into the sump when you pull the piston out. Probably better not to have bits of hard metal ring floating round in the sump or wasting hours trying to find and remove it.

Also you will probably want new head gaskets as well.  May be able to re use them but i'd be putting in new ones anyway.  Last thing you will need is to be pulling the thing down again or chasing some problem related to that. Shims may be re-usable but check. 1MM is a Lot to be padding out with shims/ gaskets.

Hope it goes well.
Be interesting to see some pics of the rings in the bore, the insides of the bores and the piston walls.