Author Topic: cracked piston  (Read 603 times)

vegoil

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cracked piston
« on: March 30, 2020, 03:31:26 PM »
I have been having bad luck!
renewed the cylinder and piston Because the old piston gudgon pin broke and went threw the side of the cylinder.
I have set the bump to 0.095thu thinking there was to much firing compression. also checked the injection timing to what i thought was 20 Deg zig zag mark using the spill method using a short tube so I could see when the fuel stopped flowing. It turns out that there are two marks on the flywheel one mark 20 Deg but mostly been ground away, and the second mark 26 Deg that was the one I had been using!! Because I am running on WVO it was set even a Little further advanced.

I wonder If this is the cause of my second Piston only lasting for a week! before it cracked blowing out oil and fumes threw the breather.

Any Ideas Please

listeroil

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Re: cracked piston
« Reply #1 on: March 30, 2020, 10:16:16 PM »
Pistons got to be the problem. The barrel looks like an Indian one I bet the piston is as well.  Get the seller to replace it.

saba

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Re: cracked piston
« Reply #2 on: March 31, 2020, 12:37:28 AM »
I think you need to send some pictures of the piston.
I used a few parts from india the barrels/liners were garbage with cast pockets in the liner surface, and leaking water threw the block. Pistons looked fairly ok.

Did some pretty stupid things but nothing ever broke big time.

Greetings Bernhard

snowman18

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Re: cracked piston
« Reply #3 on: March 31, 2020, 06:50:22 AM »
Would be interesting to have a sample of that cracked piston shot with an XRF to see what the composition of the metal alloy is.

As in China may back yard foundry's cast parts from a common mold, so there's absolutely no quality control.

This video shows people in China working their backyard foundry's just look at the type of scrap metals being brought in by the peasants.

The video below the first one  shows a backyard foundry in India.

https://youtu.be/60_Q-kAZbXA

https://youtu.be/VpZwFu91Nq8?t=3

mikenash

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Re: cracked piston
« Reply #4 on: March 31, 2020, 08:27:47 AM »
In automotive diesels I think cracked pistons tend to be from trauma?

For example, our Fonterra fleet experimented with LPG-fuelled diesel engines years ago - they went like the clappers but cracked pistons were the result

I wonder if having the injection timing substantially wrong could add "load" or "shock" to combustion forces?

Better-educated brains than mine will know

glort

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Re: cracked piston
« Reply #5 on: March 31, 2020, 11:53:02 AM »

How did it sound when it was running?

If the timing was advanced enough to crack the piston, I think you would have heard it.  Would have been a metallic ringing sound.
The fact it didn't alert you makes me think it wasn't that bad and probably just a shithouse piston.

I did once play with the timing on my truck and set it too far advanced and the thing ran about 5 seconds before I could tell  it was off.
Also run too much Meth in the water injection which causes premature ignition and you sure as ship don't miss that either.

If you did load the engine and it was far enough advanced to cause damage, I also would bet you would notice a power loss because  the piston  would be getting hammered down when it was trying to go up. Probably would have thrown the piston in the bore opposite the thrust side and made a pronounced  rattle/ ringing.  I can't see how you would have not picked up something was wrong if it was that bad.

Veg is pretty Docile stuff and burns pretty slow anyway. If you dropped the compression that may have been enough to counter the timing  problem.  You can't have too much compression with veg either.   :)

  I think if the piston was getting hammered enough to break it,you would have well and truly realised something was amiss. Probably would have required a bit more speed to get the thing to fire and been prone to kicking back a lot -if- the timing was advanced enough to cause damage.  As you didn't notice anything for a week, my guess is that you got a crook piston. 
The advanced timing - may- have brought on premature failure but even if things were fine, I'd suggest it was doomed in a month or 3 anyway.

As my father is want to say, " Just because it's new, doesn't mean it's good"

I have plenty of first hand experience to prove that's VERY true and when  dealing with China/ India parts.....  Be more like  " If it is good you are lucky".

vegoil

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Re: cracked piston
« Reply #6 on: April 05, 2020, 04:44:32 PM »
would you recommend setting the bump to what it is in the Lister hand book 0.075" to 0.080" rather than lowing the compression to 0.095" and the timing 18 Deg 2 Deg retarded.

as I mentioned before the timing marks on the flywheel may have been wrongly marked in the factory Back in 1959 as the zig zag is 26 Deg the 20 Deg has been ground away. I am now going to use a digital inclinometer as in the last post's photos.

There has always been a knocking sound. I had a visit from a garage mechanic he had a listen to the original Lister CS 8/1 engine he told me that that old type of engine all sound like that. I am thinking that he needs his hearing tested!

I am waiting on a replacement piston from the company I bought it from, as they are going to replace it free of charge.
« Last Edit: April 05, 2020, 05:44:20 PM by vegoil »

vegoil

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Re: cracked piston
« Reply #7 on: April 07, 2020, 05:22:31 PM »
this is a photo of the piston. I have found out that the top ring that came with the piston was wrong it was chrome.
that may explains why there was blow by heating the side of the piston, then crack.

answers Please.

sirpedrosa

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Re: cracked piston
« Reply #8 on: April 07, 2020, 07:06:27 PM »
Hi Veg

this is a 8/1, wright?

Is the cylinder bore chrome? if so, it cant have a chrome ring because is to hard!

In my point of view this piston was hited by start spray. Its splited at middle line of wrist pine (small end).

Does it have more symptoms?

that knocking sound seems to be early injection point.

Keep giving news, and stay safe.
VP
« Last Edit: April 07, 2020, 07:58:10 PM by sirpedrosa »
Bernard 18A - 1968 (mama's water pump - year of my birth)
Petter PAZ1 - Jun 1967, 3HP, sn 416xxxx
Petter PAZ1 - Nov 1979, 3HP, sn 425xxxx
Lister 12/2 - 12651227, the pearl!

vegoil

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Re: cracked piston
« Reply #9 on: April 07, 2020, 08:20:42 PM »
Yes this is an old 8/1 The bore is India chrome it don't look it but apparently it is, I realise now that it was the wrong ring.
what do you mean by:{In my point of view this piston was hited by start spray}
« Last Edit: April 07, 2020, 09:44:57 PM by vegoil »

sirpedrosa

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Re: cracked piston
« Reply #10 on: April 07, 2020, 09:45:42 PM »
Hi Veg

Start spray ignites very earlier, and so the piston is farway from TDC, therfore it will break the least strong piece, in this case alu piston.

Chrome bores CANT have chrome rings, its hard metal work in hard metal. Can you see result of this friction?

Chrome bores need soft rings...

Stay safe.
VP
« Last Edit: April 07, 2020, 09:50:04 PM by sirpedrosa »
Bernard 18A - 1968 (mama's water pump - year of my birth)
Petter PAZ1 - Jun 1967, 3HP, sn 416xxxx
Petter PAZ1 - Nov 1979, 3HP, sn 425xxxx
Lister 12/2 - 12651227, the pearl!

glort

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Re: cracked piston
« Reply #11 on: April 08, 2020, 01:52:14 AM »

Starting fluid ( eather) has a bad fabled reputation.  I must have read 100 times warnings where people say  engines get "Addicted " to it.
A lump of iron develops a chemical dependence to a certain Chemical?  I don't think so Tim!.  What happens often is people use the spray to start an engine with another problem ( low Compression, worn valves, bad spray pattern) and don't fix the underlying cause. With more run time the problem naturally becomes worse and it is harder to start without the starting Fluid.... Logical enough.

The problem I see with teh start Fluid and I have used it particularly in cold weather  it that like so many other things, Instead of using it correctly, Redneck Morons want to empty half a can into an engines intake and then when it goes boom and something breaks, they blame the starter fluid not their own stupidity in using it in a way it was never meant to be used.

I have also used Alcohol ( Metho, methanol, ethanol) as a start fluid which works well and just plain old petrol. A SMALL shot down the intake  works wonders for cold starting. On one of my old mercs I had a strong Methanol/ water mix in a washer bottle under the bonnet with  an " Injector through the top of the air cleaner lid into the manifold. When Starting on cold mornings I'd Glow it , give it a couple of seconds on the meth mix and crank it.  Lit up every time even on straight WVO in winter.  Both those Mercs I had were never easy starters where later Vehicles would Fire no problem with just a glow.

I used pertol and metho on stationary engines but the trick is to only use enough to get them to fire. 2 Combustion strokes is about all you need to get the engine spinning fast enough for it to continue from there if everything else is in the good condition it should be in.

Starting fluid is not the problem, its the ignorance of the human holding the can that doesn't  read the directions or uses it to try and over come other mechanical issues with the engine. 


dieselspanner

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Re: cracked piston
« Reply #12 on: April 08, 2020, 07:03:41 AM »
Spot on Glort!

Every brickies labourer should be forced to read and understand the instructions for use of 'Angels Breath' before being allowed to start the mixer.

Mind you, there's a lot of farmers and small boat owners keeping diesel mechanics in business too....

Cheers
Stef
Tighten 'til it strips, weld nut to chassis, peen stud, adjust with angle grinder.

vegoil

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Re: cracked piston
« Reply #13 on: April 08, 2020, 08:39:50 AM »
I have never used easy start spray on this engine. it's a start o matic so starts and stops on It's own when it's working!

sirpedrosa

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Re: cracked piston
« Reply #14 on: April 08, 2020, 11:55:04 AM »
Hi Veg

One thing for sure, this piston broke, and the next will brake also IF the other issus still not resolved. Take a close look at firing time.

Have you seen how I had done with my 12/2?

Stay safe
VP
Bernard 18A - 1968 (mama's water pump - year of my birth)
Petter PAZ1 - Jun 1967, 3HP, sn 416xxxx
Petter PAZ1 - Nov 1979, 3HP, sn 425xxxx
Lister 12/2 - 12651227, the pearl!