A few weeks ago my petcock sprouted a leak. I already had one needing repair in my junk box, so I decided to tackle the repair of both at once. Here’s how I tackled the job.
Notice that the cover plate is swaged on? Some would say “riveted” though they’re not technically rivets. It’s tempting to drill off the “rivet heads”, but wait. You’ll need a well centered screw hole to put it back together. Use those “rivet” dimples to center your drill. I drilled a .070” pilot hole, followed by .089” to take a 4-40 thread. Both holes on the basic petcock are through holes. On the vacuum petcock, one through hole and one ¼” deep blind hole.
Next I used a flat file to remove the “rivet heads”. They’re aluminum and much softer than the steel cover plate, so it’s an easy task. I went ahead and tapped my 4-40 holes at this point.
Then carefully pry the cover plate off. It’s still swaged on tight, so go slowly and work your way around the perimeter several times. Once the cover plate is off, I enlarged the holes by just .002” to ease reassembly, and brushed it clean.
The first problem I encounter is a broken outer seal o-ring (left). This is a “double seal” 3/32 inch wide x ⅞ inch inner diameter, AS568A-118. I bought the actual double-seal (McMaster p/n 90025K246), but the round o-ring is much more widely available and will work just fine.
The next problem is with the inner seal.
A chunk is missing from the front side.
But the back side still looks servicable.
For one of my repairs, I’ll just turn the seal around and use the better side. For the other petcock, I’ll try something else.
It looks like a new seal is available from Honda
but I wasn’t completely sure the fit was right, and I felt like experimenting anyway.
I used standard o-rings. Size AS568A-107,(3/32” wide x 7/32” inner diameter) fit the ports snugly, but bump into one another a bit. I sanded flats onto them to fix the problem.
And then they fit fine.
Lube with a non soluble grease like Molykote and reassemble with 4-40 x ¼” screws.
It's a new repair and it remains to be seen how long it will last, but I'm hopeful. At least it's working again for an investment of 40c in o-rings.
Notice that the cover plate is swaged on? Some would say “riveted” though they’re not technically rivets. It’s tempting to drill off the “rivet heads”, but wait. You’ll need a well centered screw hole to put it back together. Use those “rivet” dimples to center your drill. I drilled a .070” pilot hole, followed by .089” to take a 4-40 thread. Both holes on the basic petcock are through holes. On the vacuum petcock, one through hole and one ¼” deep blind hole.
Next I used a flat file to remove the “rivet heads”. They’re aluminum and much softer than the steel cover plate, so it’s an easy task. I went ahead and tapped my 4-40 holes at this point.
Then carefully pry the cover plate off. It’s still swaged on tight, so go slowly and work your way around the perimeter several times. Once the cover plate is off, I enlarged the holes by just .002” to ease reassembly, and brushed it clean.
The first problem I encounter is a broken outer seal o-ring (left). This is a “double seal” 3/32 inch wide x ⅞ inch inner diameter, AS568A-118. I bought the actual double-seal (McMaster p/n 90025K246), but the round o-ring is much more widely available and will work just fine.
The next problem is with the inner seal.
A chunk is missing from the front side.
But the back side still looks servicable.
For one of my repairs, I’ll just turn the seal around and use the better side. For the other petcock, I’ll try something else.
It looks like a new seal is available from Honda
but I wasn’t completely sure the fit was right, and I felt like experimenting anyway.
I used standard o-rings. Size AS568A-107,(3/32” wide x 7/32” inner diameter) fit the ports snugly, but bump into one another a bit. I sanded flats onto them to fix the problem.
And then they fit fine.
Lube with a non soluble grease like Molykote and reassemble with 4-40 x ¼” screws.
It's a new repair and it remains to be seen how long it will last, but I'm hopeful. At least it's working again for an investment of 40c in o-rings.