The Jack's Small Engines Forum - Join Our Online Community
Reply to post

Hot!Briggs 21 HP Single Cylinder. Bad rings?

Page: < 12 Showing page 2 of 2 - Powered by APG vNext Trial
Author
SRTsFZ6
Super Member
  • Total Posts : 2276
  • Scores: 80
  • Reward points: 0
  • Joined: 2018/11/18 07:20:58
  • Status: offline
Re: Briggs 21 HP Single Cylinder. Bad rings? 2025/06/18 16:14:09 (permalink)
0
 I found this on another site and believe it to be credible and make sense:
 
 
Rings rotate in the grooves unless they are pegged .
The spring of the ring does not create the compression, it is the gasses trying to get past the ring which forces them out to make the seal with the oil on the bore & in the ring groove .
This is why on 4 strokes champhers always point up.
When new the rings have not made their seal against the bore so spacing them 120 degrees helps the initial compression.
 
Of course a shop manual would give you conclusive answers...
 
 
 
.
 

Scott
doug2500
Starting Member
  • Total Posts : 13
  • Scores: 0
  • Reward points: 0
  • Joined: 2025/05/15 16:53:11
  • Status: offline
Re: Briggs 21 HP Single Cylinder. Bad rings? 2025/06/18 18:52:20 (permalink)
0
That is the most intelligent thing I've heard all day about the bevel. I'm an engineer and it's really good to understand why you're doing something, not just knowing you are supposed to do it. I pointed them both up.
 
One thing I'm not confident about is how deep I installed the main seal on the drive side. First I put it in flush, but the flat part of the crankshaft was right at the edge of the seal, so watching another video where the guy drove it all the way in, I just did that. I can't see how it would hurt, but the shiny part of the shaft that is now showing tells me that the original seal was probably flush. I have a second seal if that was not a good idea.
 
Also, the bolts holding the two halves together had some kind of lock tight or sealer on them. Is that needed for putting it back together?
SRTsFZ6
Super Member
  • Total Posts : 2276
  • Scores: 80
  • Reward points: 0
  • Joined: 2018/11/18 07:20:58
  • Status: offline
Re: Briggs 21 HP Single Cylinder. Bad rings? 2025/06/19 06:37:30 (permalink)
0
There's an oil hole in that recess that CANNOT be covered up,
IE; seal NOT PUSHED DOWN FULLY INTO THE HOLE..
 
Anywhere in the cover leaving the oil opening clear AND the working part of the seal fully intact with the crankshaft. 
A little oil between the crank and seal wouldn't hurt Flush is fine and you should still be able to see the opening... 
 
*As a side note, on my 18HP Briggs, that seal started leaking after 5 years. 
I took a short cut and pulled it with the engine in the machine
(drill and use sheet metal screw to pull the seal-
Ultimately nicking the crankshaft.) 
Now THAT FIX- Pulled the engine and cover
and seal.  I had about 1/4 crankshaft NOT damaged on the end not damaged.
I put the seal into the case, JUST ENOUGH to catch the case and ride on the 
un-damaged part of the crank.  Used Yamaha case sealer on the outer edge of the seal.
There was just enough "good crank" and just "enough cover" -
Re-assembled, stayed and is currently nice and dry..
(A major screw up with a positive ending)
 
 
.
.
post edited by SRTsFZ6 - 2025/06/19 06:39:47

Scott
Page: < 12 Showing page 2 of 2 - Powered by APG vNext Trial
Jump to:
Copyright © 1994 - 2016 Jacks Small Engine & Generator Service, LLC
© 2025 APG vNext Trial Version 5.5