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Piston marking

Tiny
DONOVANBENT
  • MEMBER
  • 1997 MAZDA 626
  • 2.5L
  • 6 CYL
  • 2WD
  • MANUAL
  • 218,000 MILES
What do the markings on the piston head mean? Trying to find a quick way to tell if they are standard or oversize. My current pistons on have two numbers.
Thursday, March 28th, 2019 AT 12:53 AM

5 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning,

If the pistons were oversize, they would be marked on the top with numbers such.010 or, 020.

The best way to check is to measure the bore of the cylinder and the size of the piston.

Roy
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Thursday, March 28th, 2019 AT 6:01 AM
Tiny
DONOVANBENT
  • MEMBER
  • 3 POSTS
Hi Roy, thank you for the reply. The problem I have is that I have not come across this type of marking before so I thought that these would be Mazda in-house code. I speak under correction but one piston is marked 23 and I think the other 80. I have noted that this particular engine is an interference type engine but mine has recessed pistons. I bought this engine as an import, but it smokes like a chimney. Complete refurbished of the head. Still smokes.
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Thursday, March 28th, 2019 AT 6:24 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Got it.

Most likely the rings are bad. To order rings, you will need to give the parts company the diameter of the cylinder to get the correct part.

Roy
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Thursday, March 28th, 2019 AT 6:31 AM
Tiny
DONOVANBENT
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Hi Roy, thanks for the help.
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Thursday, March 28th, 2019 AT 6:33 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
You are welcome.

Always glad to help.

Roy
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Thursday, March 28th, 2019 AT 6:45 AM

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