Sound like you might be on the right track there Pete - try a washer, fibre, or for preference, copper, and see wot 'appens > I know, an old chestnut! > > I am babysitting a locomotive for a person who is emigrating, it is a > 7.25" 0-4-0 "Hercules". > > I was at Swindon track yesterday with the locomotive for a boiler test, > all was well until we came to the steam test. This locomotive has one > injector and an axle driven pump, so both must work to pass the test. > > We tried the injector and it refused to pick. We changed it for a > spare, which also refused to pick! > > Tonight I steamed it up at home using two injectors from my Hunslet > (both known to work) and neither refused to pick! > > I therefore suspect that it is not the injector itself! > > The operation was the same in all cases, water on, steam on, the symptom > in all cases is excessive overflow. There is a slight "twitter" as the > steam is first applied, but that soon goes and the overflow continues. > Adjustment of steam and water has no effect. > > I have looked at the arrangements. Steam supply is good. Water supply > is good, it is from balanced side tanks, 1/4" pipe and gentle curves. I > removed the water feed from the injector and it is running free. All > joints are tight and "air tight" as far as I can tell. > > This only leaves the clack. It certainly seals as there is no steam > coming back to the injector from the clack (I swapped enough injectors > with the loco in steam!) I removed the top from the clack and all > appeared well. The only thing I could see was that the clack used to > have a fibre washer sealing the top to the body. Only the remnants of > the washer were left and the clack was sealed using PTFE tape. I don't > consider the PTFE tape was causing a problem, but could the absence of > the fibre washer reduce the lift of the ball to the extent that even if > the injector wanted to pick, it couldn't get rid of the water fast > enough, causing the overflow? > > I am not an expert on injectors, so can somebody advise where to look? > > Cheers > > Peter > > > > > > MODEL ENGINEERING DISCUSSION LIST. > > To UNSUBSCRIBE from this list, send a blank email to, > modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line. > MODEL ENGINEERING DISCUSSION LIST. To UNSUBSCRIBE from this list, send a blank email to, modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.