Hello
This is the leaking fuel tap on our Cav 30. I think the packing material round the spindle has gone. I am going to replace the entire unit rather than faff around.
Is it likely to be NPT or BSP threaded?I am going to have to drain all the diesel out. I don't know of a way of checking what the size is.
Any Australian suppliers of a replacement? WW only sells a three way which is no good to me.
Otherwise I think I will go with this -> www.amazon.com/Moeller-Fuel-Shut-Off-Valve-Brass/dp/B000MT95FA
Thanks v much.
Ed.
Ed,
It would be hard to tell what thread form you have until you disassemble and try. I know you were not keen on mucking around repairing the tap, but I would estimate the leak could be coming from the gland in the tap spindle, if it is from the thread seals, well someone before you has possibly mixed and matched NPT to BSP?
You could remove the tap, and plug the opening temporarily whilst you replace the o-ring or and you maybe good to go!
Cheers Richard
Its tough to measure the difference without a proper thread measuring tool, but I'd guess that since the boat was probably built in NZ the fittings are BSP. NPT is usually only found on North American equipment.
On 1/4" or 3/8" fittings, BSP is 19 threads per inch, NPT is 18 threads per inch. The angle of the thread pitch is slightly different as well. BSP is 55 degrees vs 60 degrees. 1/4" BSP and NPT will screw together , but chances are they will leak.
If the fittings are 1/2" or 3/4", both BSP and NPT are 14 threads per inch. The pitch is still slightly different but they will usually not leak unless under pressure.
If it is the stem packing leaking, that can sometimes be sealed by opening the valve slightly, then hold the handle while tightening the bonnet cap.
