Re: 25HP Merc Compression Leak? Any ideas? [ Ol' Paw's Boat Motor Bulletin Board ] [ Ol' Paw's Fishing Page ] Posted by Spike (24.58.92.156) on October 03, 2004 at 15:57:02: In Reply to: 25HP Merc Compression Leak? Any ideas? posted by Mark on October 03, 2004 at 11:51:52: Most compression gauges I`ve seen have a schrader check valve to keep pressure from leaking out of the gauge sometimes there is a botton to release the pressure without messing with the schrader valve.If either valve was erratic it could leak out.Assuming there is no such valve on yours if your motor were to stop in the right spot your pressure would leak out instantly through the exhaust ports.If it were to tend to stop in a position near the ports it might leak a little. The rings could be leaking a little. You could do a decarb(decarbonize) with one of the decarb products to see if it improves things.The crab won`t affect a compression leak.Of course there is the obvious it could be leaking out around the gauge fitting.If it is a head gasket it should soon show more.You could use it while you are trying to figure if anything is wrong.

Re: 25HP Merc Compression Leak? Any ideas?

[ Ol' Paw's Boat Motor Bulletin Board ] [ Ol' Paw's Fishing Page ]

Posted by Spike (24.58.92.156) on October 03, 2004 at 15:57:02:

In Reply to: 25HP Merc Compression Leak? Any ideas? posted by Mark on October 03, 2004 at 11:51:52:

Most compression gauges I`ve seen have a schrader check valve to keep pressure from leaking out of the gauge sometimes there is a botton to release the pressure without messing with the schrader valve.If either valve was erratic it could leak out.Assuming there is no such valve on yours if your motor were to stop in the right spot your pressure would leak out instantly through the exhaust ports.If it were to tend to stop in a position near the ports it might leak a little.
The rings could be leaking a little. You could do a decarb(decarbonize) with one of the decarb products to see if it improves things.The crab won`t affect a compression leak.Of course there is the obvious it could be leaking out around the gauge fitting.If it is a head gasket it should soon show more.You could use it
while you are trying to figure if anything is wrong.