It’s possible for the rings to wear and loose tension, with the piston and bore showing little sign of wear. At least total failures,usually involve damage to at least the piston, and often the bore An air leak or carb fault makes the saw run lean, it overheats, and the piston starts to physically melt. If the piston and bore are good, then rings is probably all it needs.
If the piston and bore are good, then rings is probably all it needs. You can usually save the cylinder if the saw has been run lean and melted the piston to the point it seized the rings. No more than quality Meteor pistons cost and as much trouble as it is to tear the saw down I don’t often just replace the rings.
They can be all over the map when you change the squish… what I go by is the feel when you put a steady pull on the starter cord, that will tell you how much it’s leaking down. If it rolls over and stops you dead, the rings are good, if it’s easy to get it to roll up to TDC with a couple pounds of pull on the rope, they’re done.
You really don’t want to twist the piston once you have it seated in the cylinder, so get the alignment as close as possible before you push the piston in. Repeat the process for the remaining ring and then you can move on to attaching the piston to the piston rod. Then slide the piston and cylinder into place so that the inside of the roller bearing and the hole in the bottom of the piston line up.
when to replace chainsaw piston Related Question:
When should a piston be replaced?
According to Suyenaga, if the pin bore is worn more than 0.002-inch, JE recommends the piston be replaced. Other potential failure points include inspecting the rings to ensure the ring end gaps, especially the top ring, has not butted.
Do I need to replace my pistons?
Any pistons that are worn or damaged must be replaced. In most cases, if one piston is bad, the others are too so, all should be replaced as a complete set. Many pistons that appear to be in good condition and show no signs of scuffing may still have to be replaced because the upper ring lands are worn.
Should I replace pistons or just rings?
Do I Need To Replace Piston Or Just Rings? In the case of an overheating engine and the oil control rings have lost their tension, then the rings should be replaced, as the engine is burning oil as a result. In the event of excessive wear, you should replace the worn out cylinders with new oversize pistons and rings.
How much piston damage is OK?
JE’s axial clearance recommendations will vary with specific pistons, but a generic clearance of 0.001 to 0.002-inch is acceptable. This can be measured with a feeler gauge between the top of the ring and the groove.
What causes pistons to go bad?
A damaged piston can be a result of:incorrectpiston (too small for the cylinder),excessive rocking of the piston, insufficient compression, fuel flood, bent connecting rod, excessive clearance at the conrod bearing, uneven or pitted cylinder walls, lack of lubrication.
How long should pistons last?
Due to this situation, piston rings typically last about 50,000 to 250,000 miles since they can be checked for wear. Piston rings are usually able to last about 100,000 miles on average. Replacement of damaged or worn out piston rings is essential.
Is it expensive to fix a piston?
The average auto mechanic charges between $100 to $200 per hour to replace a blown piston. A new piston ring costs around $100, so you’ll have to add that to the cost of how long it takes your mechanic to complete the job.
Is it OK to reuse pistons?
If the old pistons measure and spec out fine, go ahead and reuse them. Keep in mind though, aluminum does not have an infinite fatigue life like steel. At some point, aluminum will fail due to fatigue, no matters what. Used pistons are just that much closer to an end of life fatigue failure.
Do you need new pistons after boring?
If you over bore the cylinder, you must use a new piston. When clearances of the piston to wall are measured in the thousandths of an inch (or sub-millimeter) and you bore the cylinder +. 010″ over (or +. 030″ or whatever), there is too much gap for the old piston to take up the slack.
What happens if you don’t replace piston rings?
When the piston rings fail, they cannot keep the oil from leaking into the cylinder; as soon as the oil leaks, it will get mixed up in the combustion process. Slowly and gradually, all your engine oil will leak into the cylinder, and you will witness a drop in your car’s engine oil level.
How long do piston rings last?
Piston rings are typically built to last as long as the engine. As a result, piston rings usually last somewhere between 50,000 miles to 250,000 miles depending on their maintenance. On an average, the life expectancy of piston rings is around 100,000 miles.
Do pistons have to go back in the same cylinder?
Unless the cylinders have been honed to fit each individual piston, you should be able to swap them freely. Technically, the rods don’t have to go back on in any particular order. They do have to be correctly oriented. “Smooth side” facing each other and “beveled side” facing away from each other.
Can I reuse pistons in a rebuild?
One option for reducing the cost of an engine overhaul rebuild is to reuse the pistons. The pistons are typically the single most expensive part in a rebuild kit. Taking them out can make the kit affordable for nearly everyone’s budget.