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Discussion Starter · #1 ·
Hi wondering if anybody can point me in some kind of direction with this issue...
Lately the PTO plug porcelain has been cracking and the cylinder starts to miss and fart and eventually it won't run on that plug at all. I did a compression test and I have 148 and 149. Been through 4 plugs now and each one ends up cracked and not working?
 

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Discussion Starter · #2 ·
This is on a 2007 600 sdi.
 

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Discussion Starter · #4 ·
yes every time. new plugs in and it runs great for 30-60 miles then it starts to mis-fire, bog, until it ends up running on one cylinder.
 

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And all on the same cylinder?
 

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Discussion Starter · #6 ·
Yes just the PTO side.
 

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Which portion of the porcelain, between where the cap fits and threaded metal shell, or the portion in the combustion chamber?
 

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NGK Plug Studio

1) Breaking of the insulation Type 1 (See Photo 1)

  • When selecting a plug, make sure that the standard plug will not go outside the optimum temperature range while engine combustion is normal (refer to the "Plug Temperature and its Effects" chart below). If for any reason (water leakage, oil leakage, etc.) the engine starts knocking or detonation occurs, the temperature of the combustion gas will rise sharply and the plug, piston and valves will overheat. Overheating of the plug causes the center electrode to expand, and this can break the insulation.

Photo 1: Breaking of the insulation
photo1.jpg


2) Breaking of the insulation Type 2 (See Photo 2)

  • This is the situation where deposits (products of combustion of oil, etc.) penetrate into the gap between the center electrode and insulation at the firing end, expanding the center electrode and causing the insulation to break.
  • Normally, deposits do not penetrate into this gap. If the engine overheats, the engine's cylinder head may distort. This means that cooling of the combustion chamber will fail which in turn means that knocking will occur more easily. Repeated knocking leads to abnormal pressure and vibration in the combustion chamber. This abnormal pressure and vibration causes the deposits that have accumulated in the combustion chamber to scatter as fine particles and enter gaps in the plug.

Photo 2: Entry of deposits
photo2.jpg


cause.gif


  • Excessive advance of ignition timing →
  • Fuel-air mixture too lean →
  • Leakage of cooling water or oil →
  • Plug incorrectly tightened →
  • Plug with a low heat rating used →
  • Plug heat rating reduced by accumulation of deposits →

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  • Adjust the ignition timing.
  • Inspect and adjust the fuel system.
  • Inspect and repair the leak.
  • Tighten plugs with the recommended torque.
  • Use a plug with the standard heat rating.
  • Change the plug.

If the engine is not performing properly and on removing a spark plug it is found that the electrodes have melted or the porcelain insulation has broken, this could be construed as a spark plug fault, but note that some other possible causes for the poor engine performance are problems with the valves, valve seats or pistons.

photo6.jpg
 

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Discussion Starter · #9 ·
The portion that is cracked is the ceramic/porcelain white area above the engine head when installed. (The portion outside of the engine). I'll post some pics tomorrow.
 

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Mr Top Whore
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Wondering if you have a broken motor mount or engine stopper or something? Causing that much rattle to keep snapping the porcelain on the same plug?
 

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The portion that is cracked is the ceramic/porcelain white area above the engine head when installed. (The portion outside of the engine). I'll post some pics tomorrow.
I think this will be a slam dunk. Get a new ignition coil assembly from a part out in the DooTalk classified ads and your done!

You can also contact site sponsor Twinpower or Loclass to see if they have any as they part out sleds. Click-idly click their handlenames and choose Send me a Message at the top right of their Profile.

Flashover caused by faulty insulator boot

- from Bosh Industrial Spark Plug Failure Modes click-idly click

"Spark is traveling over ceramic from the terminal stud to the housing. Check insulator boots for proper fit and replace if necessary."

Automotive tire Cylinder Gas Circle Metal
 

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Definitely depends where and wow it's cracking?

But you might have it there Daag
Definitely. A cracked insulator along the length of the plug is such an odd problem that I think it could only be caused by the electricity generating abnormally high heat. With four in a row I think the OP should buy a lottery ticket. I don't think we could replicate the problem even if we wanted to. Actually I would love to get my hands on that dual coil pack for a closer look and maybe even put a timing light and spark tester to it.

That has me thinking, rave_man, can you run the sled on a stand during the evening and close all the garage lights? I would love to know if you can see any signs of an arc along the plug. Check from all sides, LH, RH and front. I have seen all kinds of arcs along the ignition coils, but never on a plug. It would be cool to get a picture of this.

From Wikipedia

https://en.wikipedia.org/wiki/Arc_flash

An arc flash (also called a flashover) is the light and heat produced as part of an arc fault, a type of electrical explosion or discharge that results from a low-impedance connection through air to ground or another voltage phase in an electrical system.
 

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Rave_man, before you think about hacking away at the plug wires, I am willing to buy it once you are done fixing the problem. This should cover part of the cost for a used replacement.
 

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What are you using to tighten the plug with? Flashover generally leaves a carbon track and has a misfire, not broken porcelain. Where are you getting the plugs? Porcelain shells get cracked when the plug is dropped before installation, did you buy a box of plugs from a store or were they shipped?
 

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Discussion Starter · #17 ·
Here are 2 of the four plugs with cracks. lots of dark soot up in the plug boot too. So you think the boot is faulty? or is something causing this with the stater? Its only on the one side. My thought was if the stater was faulty both plugs would be affected?
 

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Discussion Starter · #18 ·
What are you using to tighten the plug with? Flashover generally leaves a carbon track and has a misfire, not broken porcelain. Where are you getting the plugs? Porcelain shells get cracked when the plug is dropped before installation, did you buy a box of plugs from a store or were they shipped?
i'm using the toolkit wrench to tighten. I got them from Canadian Tire. br8ecs and i didn't gap them. They definitely weren't cracked to begin with. They were visually perfect. They cam in a 2 pack.

The other 2 plugs are from Canadian Tire but I bought them a few years ago.
 

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Discussion Starter · #19 ·

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Discussion Starter · #20 ·
Rave_man, before you think about hacking away at the plug wires, I am willing to buy it once you are done fixing the problem. This should cover part of the cost for a used replacement.
You want the insulated plug end?
 
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