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| Gray Marine Model U 3rd Piston Ring |
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tmann
Member
Username: tmann
Post Number: 19
Registered: 09-2015
| | Posted on Tuesday, February 28, 2017 - 11:46 pm: | 
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I'm looking for information on a source for the third ring down on the piston skirt of a Gray Marine Model U one cylinder.
It was running fairly good, then not, and compression had dropped to abt. 40 #.
I took it apart, thinking a ring job should solve my problem, but found that the third ring was broken, with a piece of the ring missing from the gap end.
Don't know if the piston is the original or not, but the third ring mics out at 3.5"x 1/4,but is only abt. 9/128" thick?
I was gong to mill out the groove deeper, and use some standard ring, but the skirt is only abt. 4.70 mm thick there, so not much depth can be added to the groove .
Any suggestions on how to proceed?
Better yet, would anyone happen to have a piston and set of rings they could get rid of for a reasonable price?
Thanks,
TMann
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jb_castagnos
Senior Member
Username: jb_castagnos
Post Number: 1285
Registered: 07-2002
| | Posted on Wednesday, March 01, 2017 - 10:30 am: |
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The third ring won't affect compression, a leakage from the first two would go through the wrist pin, it's there to help seal crankcase compression and to keep oil going to the wrist pin. The usual procedure is to order standard thickness and machine the inside bore. |
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