Fixing poor leakdown, Cyl 1 leaks at 50%, rest are cool. |
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Fixing poor leakdown, Cyl 1 leaks at 50%, rest are cool. |
VaccaRabite |
Oct 24 2007, 07:00 AM
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#1
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En Garde! Group: Admin Posts: 13,475 Joined: 15-December 03 From: Dallastown, PA Member No.: 1,435 Region Association: MidAtlantic Region |
So, at the Sterling meet I did a leakdown test on my motor, and found a problem with Cylinder 1. 45% leakdown, but 120 lbs of compression. Was tempted just to let sleeping dogs lie, but pulled the head off.
What was going on was clear as soon as we did that, the head was not totaly sealed to the cylinder, off by a very small amount. Instead of having the head recut, I decided to try and lap the two of them together. So, last night I hand lapped them, using ground graphite to check for even contact. I got good contact after the third round of hand lapping (lap, clean, check). Now I need to get the jug back on the block. I have a ring compressor on the piston, but I can't ficgure out how to get the head back on. Do I have to take the piston head off the rod? If so, how do I get it off. It looks like that tis a spring keeper that needs to be removed. Is there anyhting on the rod the needs to be loosened before I can pull the pin out to remove the piston head? Obviously, if there is a trick to getting the jug back on without pulling off the piston head, I'd like to do that. Zach |
VaccaRabite |
Dec 27 2007, 12:15 AM
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#2
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En Garde! Group: Admin Posts: 13,475 Joined: 15-December 03 From: Dallastown, PA Member No.: 1,435 Region Association: MidAtlantic Region |
Well I had time to work tonight, so I did more testing - just to make sure. I also did some experimenting with the leakdown tester.
1) the directions say not to run the leak down tester above 80 psi - but they don't say that you get a false reading if you run it below 80 psi. I was running it tonight at 70 PSI to be nice to the tool, and could not figure out why all my measurements were 10% higher. But it back at 80PSI and it was golden. 2) The leak down tester was leaking in 2 places. I put in some fresh teflon tape and that was fixed. I was REALLY hoping that was the cause of my leakdown - jsut the tool being out of whack. But, it wasn't. I checked the valves for bubbles, and they were sealed tight. The cylinder to head join only bubbled in 1 location - between the cylinders. Everywhere else seemed to be fine. Tomorrow morning I am going to pull the head and start taking measurements. I really hope I just need to get the head recut a little. Zach |
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