Sanborn air compressor leaking down
by Tom Sawyer
Hi Bill hope you can help
I have a Sanborn b5900 that I was having build up problems with
I found one of the intake disc cracked and ordered a new valveplate through mastertoolrepair they told me that there is a new style reed valve plate available so I purchased it and the ness gaskets to install it with.
My build up problem is solved but now my comp leaks down overnight I have been a tech for 40 years and know how to repair just about anything the cylinders were in nice condition no ring ride no scoring I torqued the head in a 3 step sequence final at 33 ponds the co says there is no way the plate will cause leak down and wont war the plate as I said no leaks down prev I need some help I have isolated the pump and it still leaks down any ideas
Tom, typically if an air compressor leaks air slowly, and there are not leaks audible or visible, then it points to the tank check valve not seating properly.
Possibly when you were repairing the compressor some debris got sent down the line to the tank and has lodged in the check valve, preventing it from closing tightly.
If there is a seat leak in the check valve, air will leak out the unloader valve which is open when the compressor is off.