I really ought to change the oil on my newly-acquired KH. Apart from draining the tank and the sump
I usually drain the oil pipes as well. It's at this point doubts set in. I've not had anything to
do with anti-draindown valves and this bike seems to have one.
Firstly, should I not drain the oil feed pipe as the anti-draindown valve will stop the new oil from
flowing into the pipe and displacing the air?
If you get an air leak between pump and anti draindown valve, or perhaps just air between pump and anti draindown valve, the anti draindown valve is likely to fail to open. A slightly slack union caused by a fibre washer "bedding in" caused me to throw a rod on my 1954 KH so be warned. If you do see fit to empty the oil pipes, make sure you refill the feed pipe with a squirty oil can through the anti draindown valve. A better location for it, due to less volume between pump and valve, is screwed into the crankcase. (Idea courtesy of son Rob). Again though, make sure you fill the void between pump and valve with the squirty oil can (which will open the valve when you squirt it). I haven't drained the oil pipes on my KH for at least 10,000 miles incidentally, although I have changed oil and filter element many times.
The valve itself looks very like the ones I have on my KH and KHA. I forget who makes them but it is someone in South Wales.
Throwing the rod on the KH made me fit an oil pressure gauge for peace of mind. I have just finished fitting one in the same way to my KHA, in anticipation of knocking up some serious mileage on it this year.
Paul Jameson
35 LG (project), 37 RH500, 52 ex ISDT KHA, 54 KH(A), 75 Healey 1000/4.
Former Machine Registrar & Archivist, General Secretary and Single Spares Organiser (over a 25 year period).
Now Archivist (but not Machine Registrar), Gauges and Clocks Spares Organiser.
I hadn't thought of the squirty oil can either. Another of son Rob's good ideas.
Paul Jameson
35 LG (project), 37 RH500, 52 ex ISDT KHA, 54 KH(A), 75 Healey 1000/4.
Former Machine Registrar & Archivist, General Secretary and Single Spares Organiser (over a 25 year period).
Now Archivist (but not Machine Registrar), Gauges and Clocks Spares Organiser.
Sludge settles in the bottom of the oil tank so I mostly remove it and shake some Kero with roofing nuts in it to dislodge the sludge . Hose out with water under pressure and dry with a hair dryer. Purging the oil lines is much less important. Plain bearing motors need a good oil filter and crankshaft oil galleries cleaned out at overhaul or when it's been sitting for a long period.. Nev
It looks like a Bri Tie valve, same as I have fitted on my KH. I would not bother draining the oil pipes or a major priming exercise is needed as Paul describes, Check the unions for tightness regularly and they work perfectly. I had the return side union fail on mine due to a cracking pipe, fortunately the oil drip alerted me in time. I have an oil filter fitted in the return line, and feed the rockers from a t junction before the filter. the original rocker feed union on the crank supplies an oil pressure gauge. With a filter there should not be any sludge in the engine.
