Puppeteer

Author Topic: New pistons Petter PJ2, block after short time engine running. Clearance?  (Read 14444 times)

Rob PetterPJ2

  • Newbie
  • *
  • Posts: 40
    • View Profile
Hi, I'm Rob from Amsterdam, NL, new to any forum.
English is not my native language, and with the technical stuff I have to look up the english words and I may not understand everything you may try to tell me, right away, but let's give it a try.

I had no experience working on a diesel engine before 4 years ago, but I do have a technical insight. I learn while doing, and I ask a lot and read a lot, especially now that there have been and are serious problems with this old machine. I'm used to open every household thing that's broken and try fix it, and mostly I can. But I know I'm still very much a beginner with diesel engines, compared to the advanced hobbyist mechanics.

I wish I had a manual for exactly this engine Petter PJ2, 22 HP air cooled. Motor nr 13724, put in a Harding life boat in 1972.
When, after a few years the engine started to show problems (smoke, overheating) small pieces of one piston appeared to have broken off, I had an engine revision workshop find me 2 new pistons (they got them from the Lister-Petter company) and have the cylinders honed by them.
Now that I've put the engine back together, and both cylinders firing, after little time (2 minutes various speeds, 10 minutes slow speed) the engine slows down, and when I turn it off, the flywheel can't be turned for a short while, and after that only with force. When the engine cooled down, it all turns easier, as normally. I guess it's a result of the pistons expanding by the heat and then get stuck in the cylinders. The oil in the carter is Shell Rimula R4 Multigrade 10W30.
A manual of a similar engine says, with new pistons one must indeed let the engine run first for just 2 minutes, without any load, then 10 minutes let it do some work, and then longer and longer before really having it run for a normal, longer trip. What worries me, is that the first two times the engine stopped after 2 minutes, for blocking itself. The third time after about 10 minutes running slow. The pistons, or at least one, gets stuck and the flywheel can't be turned for a minute or two.
How normal or abnormal is this? To me it doesn't 'feel' good, that the pistons get stuck.
Both cylinders seem to warm up normal, and develop an equal temperature.

1. Should I be worried about the piston clearance being too little?
2. What else could cause this rapid blocking, that seems so related to the heating up?
3. Who could provide a manual for exactly this engine?

I'll of course be happy to hear some responses

ajaffa1

  • Hero Member
  • *****
  • Posts: 1402
    • View Profile
Hey Rob, I agree with every piece of advice from Glort, however he missed one thing(not like him), I would be looking at the piston ring gap. Piston rings grow as they get hot, if the gap between the two ends is too small the engine will seize after about five to ten minutes. Very easy to fix: remove the piston rings and place them in the cylinder, use the bare piston to push them down the cylinder so they are square to the bore. Use a set of feeler gauges to measure the piston ring gap at the top and bottom of the bore. If the gap is too small, file or grind the end of the ring until they are within specification. Do this for every piston ring and then reassemble. The problem should be solved.

Your English is very good, good luck, let us know how it goes,

Bob

ajaffa1

  • Hero Member
  • *****
  • Posts: 1402
    • View Profile
Hey Glort, used to do similar stuff with Cord over sized rings in the UK, my thing at the time was Mini Cooper engines. Had a few seize after a few minutes because we went too tight on the rings. Had a lot of fun with those simple engines, miss the reliability, simplicity and cheap parts.

Bob

Rob PetterPJ2

  • Newbie
  • *
  • Posts: 40
    • View Profile
I SEE NOW, THERE ARE MORE RESPONSES. I'LL ANSWER THEM RIGHT AWAY.

Thanks, Glort, for your quick reply.
Ha, you meant seizing, instead of siezing. Yes, it gets jammed.

Cooling.
There's no water cooling. It's air cooled. I'll attach a movie of an identical engine, that I found online.
https://www.youtube.com/watch?v=TxLd4O31AMY

As also that movie shows, after just two minutes of running stationary, no such engine will get jammed for overheating, even if the air cooling system isn't attached, as was also the case when I had my test runs. Do you agree, or am I mistaken? Before it was never a problem.
After two minutes running I could still touch the cylinder fans, without getting burned. But the engine was slowing down and getting jammed.

Oil supply pipe. Seems OK.
Oil does flow to the rockers of the valves. When I turned the flywheel by hand (feet, actually), and the oil supply pipe not yet attached to the cylinder heads, I saw oil was coming out at the top side of the pipe.

Oil between cylinder and piston. Seems OK.
When I had already taken the cylinder heads off, after the second jamming, to check if there was any visible damage, and then turned the flywheel by hand, I saw the cylinder wall got oil.
I'm not sure where the cylinder gets the oil from, by the way. Does it come, partly, from the oil of the valve rockers through the valve of the air inlet, or does it just splash up, from the carter, against the bottom side of the pistons and cylinder, as I read somewhere?

New pistons, slightly different from old ones.
The new pistons have fewer of those little holes for the oil to go through. The engine workshop guy says these holes are to drain off the oil, while I thought they're meant bring the oil to the cylinder wall, after it splashed up against the bottom of the pistons.
In any case, turned by hand, the pistons and cylinder wall show to get oiled.

Oil pressure. Don't know (yet)
I don't have a meter for that. But I know the oil is supplied to the valve rockers.

Bearings getting oil?.
The bearings of the pistons at the crankshaft, right?
Hm, I hope I never have to get in there, that far. Do they get oil through the crankshaft itself, or from oil splashing up? I don't have a manual of this particular engine.

"check the barrels are round and square to the block"
You mean the cylinders, right?

Barrels square to the block.
What could cause them not being attached square to the block?
When I bolted the cylinders back on the block, 6 nuts per cylinder, I took care of bolting nut 1 and 4, then 2 and 5, then 3 and 6, building up the force used in 4 phases.
But maybe the gaskets that are placed under the cylinder make one cylinder tilt a tiny bitty?
Somehow, one of the pistons doesn't reach the same height as the other one, and therefor, to get even compression, one cylinder gets a stack of gaskets under it, and the other one just one, a fraction of a millimeter thick.
Maybe that stack of 5 super thin gaskets causes a problem? Maybe some dirty under it, that I overlooked, makes a barrel tilt a tiny bit? Because tilting is what you mean, not?
What had surprised me, is that one of the (identical!) pistons didn't reach the same height to the cylinder head. What could be the cause? And earlier fixing of a problem that was before my time? Anyway, I decided the bump clearance should be equal, and therefor I took some gaskets away there and put them under the other barrel. The bump clearance is about 1 mm, now, as seems ideal for an almost similar Petter. When turned, the cylinders seem to have equal compression (very hard to get over it, pushing the flywheel with the feet) and when the engine is started, the seem to do fine, both cylinders fire and the cylinders get equally hot (felt by hand).

So, when I take the engine apart again, I'll check these gaskets and if anything would be there that make a barrel tilt.

Check the barrels are round.
OK, I will find a way to do that.

Piston clearance.
The manual of an almost similar Lister-engine "type LD" says the clearance should be no less than 0.005", being 0.127mm. BUt this is what I need  the right manual for...
Now I wonder, what did the guys of the workshop use as reference, then? I know they don't have that manual either. They surely didn't know what the bump clearance of this particular engine should be.
The new pistons definitely had a lesser clearance than the old ones, but I found that logical, for the old ones, and the barrels had been worn out.
But when I was putting the honed barrels back over the pistons, I was already worried about one not going in so well. Both of the pistons would lift the heavy cylinders up along their long bolts, when I turned the flywheel. No sliding. With oil, no sliding either. When I told the workshop guys about one piston needing more force, they said it was not unusual. Which I found strange, because it shows a difference that you don't want there to be, right? But they're the professionals, and they sometimes shake their heads when I talk with them, obviously not knowing the right terminology, the right names of the engine parts (I earlier had them check the fuel injectors, when I started with bringing this engine back to life 4 years ago, by cleaning the pipes).

When you say, the engine revision workshop guys may have 'botched' it, it is the first thing that came into my mind, when I was putting the engine back together and one piston clearance seeming so cramped.

Oil scraper ring. One more problematic.
One of the pistons went back in the barrel with more difficulty, especially for the scraper ring at the bottom. That needed some work to get it in. Different from the other piston. A second time that I took it all apart and back together, same thing happened.
Could that cause this engine getting jammed after a few minutes idle running?

Clearance again
I'll go confront the workshop with the clearance problem, again, then and ask them what measure they applied.

Glort, I'll be happy with some more of your thoughts about it all.

Cheers
Rob

ajaffa1

  • Hero Member
  • *****
  • Posts: 1402
    • View Profile
Hey Rob, every symptom you have posted suggests that the piston rings do not have sufficient gap. It`s an easy fix but takes a little time. Much better an engine that is a little tight than one that is too loose before it`s done any work.

Bob

Rob PetterPJ2

  • Newbie
  • *
  • Posts: 40
    • View Profile
[quote author=ajaffa1
"If the gap is too small, file or grind the end of the ring until they are within specification. Do this for every piston ring and then reassemble. The problem should be solved."

Hi Bob,
oh, that'd be great, if that would be all. As I wrote as a reply to Glort, one scraper ring seems to be problematic, and also the second time I worked it into the cylinder.
These rings came with the pistons from Lister-Petter. Could they put the wrong rings on it, then? But how do I know "If the gap is too small"? I haven't found the manual for this thing yet. Is there a way to calculate it?

Anyway, I'm happy to hear that such a small thing could indeed jam that robust engine.
So, I happy to have found some guys at this forum who are really helping, and not speak technical 'chinese' to me leaving me puzzled about what the h*** they mean.

One of the bolts connecting the oil supply pipe to the cylinder head (to the valve rockers) appears to be a wrong one, slightly off size, too short, wrong thread, and when I bolted it back in, not yet knowing that, it decided to end it's working life (the thread got too damaged), so I need to find me one of have it made, before I can start the engine again. That will be somewhere next week I hope.

Glort and Bob, thanks!
« Last Edit: October 18, 2018, 01:09:21 PM by Rob PetterPJ2 »

ajaffa1

  • Hero Member
  • *****
  • Posts: 1402
    • View Profile
Hi Rob, there is sure to be a formula for working out what the correct gap should be, sadly I don`t know what that is. If you post the diameter of your pistons I am sure that someone like Dieselgman or 38ac will give you that information.

I am also a little concerned that you don`t have the same bump clearance on both cylinders, please check out how to set this correctly on the WOK at the top of the home page, courtesy of 38ac.

Bob

Rob PetterPJ2

  • Newbie
  • *
  • Posts: 40
    • View Profile
I am also a little concerned that you don`t have the same bump clearance on both cylinders, please check out how to set this correctly on the WOK at the top of the home page, courtesy of 38ac.

Hi Bob, but I wrote I had adjusted the bump clearances. They are the same now by putting more gaskets under one cylinder. I did that after I saw that one piston didn't reach as high as the other one. Somewhere further down there must be something that creates a 1 mm difference. This engine has been worked on before I got it. It shows at various spots.
Cheers
Rob

Rob PetterPJ2

  • Newbie
  • *
  • Posts: 40
    • View Profile
Hi Rob, there is sure to be a formula for working out what the correct gap should be, sadly I don`t know what that is. If you post the diameter of your pistons I am sure that someone like Dieselgman or 38ac will give you that information.

Diameter of pistons: 99.6mm = 3.9212598425"
I've contacted dieselgman.

Thanks
Rob
« Last Edit: October 18, 2018, 02:48:12 PM by Rob PetterPJ2 »

ajaffa1

  • Hero Member
  • *****
  • Posts: 1402
    • View Profile
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

38ac

  • Hero Member
  • *****
  • Posts: 1828
    • View Profile
Re: New pistons Petter PJ2, block after short time engine running. Clearance?
« Reply #10 on: October 19, 2018, 03:18:18 AM »
The bump clearance on a PJ is indeed set via the number of and various thickness of the base gaskets which are actually steel shims. As I remember three different thickness are available to be used in combination as needed. That being said 1mm is a LOT or variance. Much more than,would be seen normally and can be due to issues that are not readily apparent. From what I have read on this thread you need to put down the tools until you have a manual. A person can feel his way through a simple overhaul but when an engine has suffered previously in unknown ways all that can be accomplished by me from a distance is to throw darts at it. One possibility that will not be in a manual is that the shop that honed your cylinders did not use a fixture that simulates being installed on an engine. The bores are pulled around by the clamping forces thus A cylinder that is made round while not clamped will not be round when installed.
« Last Edit: October 19, 2018, 11:01:15 AM by 38ac »
Collector and horder of about anything diesel

38ac

  • Hero Member
  • *****
  • Posts: 1828
    • View Profile
Re: New pistons Petter PJ2, block after short time engine running. Clearance?
« Reply #11 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

38ac

  • Hero Member
  • *****
  • Posts: 1828
    • View Profile
Re: New pistons Petter PJ2, block after short time engine running. Clearance?
« Reply #12 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

Rob PetterPJ2

  • Newbie
  • *
  • Posts: 40
    • View Profile
Re: New pistons Petter PJ2, block after short time engine running. Clearance?
« Reply #13 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

  • Newbie
  • *
  • Posts: 40
    • View Profile
Re: New pistons Petter PJ2, block after short time engine running. Clearance?
« Reply #14 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.