Re: CONFUSED!?!?!?!?!

Posted by Janicholson on December 17, 2006 at 07:46:02 from (66.173.50.42):

In Reply to: CONFUSED!?!?!?!?! posted by H fanatic on December 16, 2006 at 22:49:23:

Unanswered first: A groove cut in the outside edge of a piston that is not a ring groove is a heat dam. These are used to prevent combustion heat from traveling down the metal of the piston directly. Their use is quite common. cleaning them is a good idea if one is careful not to remove much metal. A ring groove cleaner with a cutter ground down to fit works well.

Ring gap provides a space for the ring to expand Circumferentially and still not touch end to end (which would sieze the engine). Ring gap should be measured in an unworn location in the bore. If looked at in a location that is worn, it is not accurate. Unworn locations can be found at the bottom of the cyl. Usually 1/2" up from the very bottom. Another location is above the top ring/ridge. (if and only if this area has never been ridgereamed or honed in some abnormal way).
In all cases the tightest gap measured on a ring in various locations in a bore, can be assumed to be the tightest spot in the bore)
One way to approximate bore taper/wear is to measure ring gap in the most worn spots (just below the top (1/16") of the ring wear area), and at the bottom as noted above. The change in Circumference converted into diameter will indicate taper in the bore (not as accurately as a set of cylinder micrometers used correctly, but good enough to determine if a cylinder is worn drastically.
All single piece oil control rings are old technology and should (in almost all cases be replaced with three piece rings with (effectively) no gap. Cleaning the ring groove is drastically important, as is doing it without removing metal. The groove clearance (side of ring to ring groove) is important because if too large it causes a pumping effect of oil around the back side of the ring. RIng groove taper (wallowing out of the squareness of the groove) is also a reason to junk the piston. Or if it is irreplacable, the groove can be cut wider and a steel repair ring can be inserted (they look like a scraper rail from a three piece oil ring) to take the piston back to usable. I hope this helps, good luck, JimN

Replies:

Add a Reply Name: E-Mail: Subject: Comments: Optional Link URL: Link Title: Optional Image URL: Email Notification: If you check this box, email will be sent to you whenever someone replies to this message. Your email address must be entered above to receive notification. This notification will be cancelled automatically after 2 weeks.

TRACTOR PARTS	TRACTOR MANUALS

We sell tractor parts!  We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today. [ About Us ]