Thursday, 1 August 2013

Oil Out, Rained Off, Oil In

After my last attempt to prevent oil leaking out of the front engine's cam-shift shaft oil chamber, I set out to cure the leak with a gasket of 1.5 mm rubberised cork sheeting.

The offending leak area is shown below in an old photo of the rear engine (which means I probably have a leak on that too!).
Oil Chamber Leak
First a little background: I poked my camera around underneath a Super Sentinel waggon at the 2013 Langport steam rally recently. Sentinel 7109 has very similar engines to the Super Waggon but mounted vertically instead of horizontally beneath the waggon's load platform.

I found the method of moving the camshaft to be quite different on the waggon. Chronologically, the waggon came first so Sentinel 7109's engines are an adaptation of the original approach.

The waggon used the 7109 oil chamber filler location to attach the shaft rotation lever, unlike Sentinel 7109 which has the lever on the end of the shaft.
Waggon shaft rotation technique
This is how it works: (Also on YouTube). Apologies for the background commentary!

Sentinel 7109, instead of having the waggon's rotating sleeve (which did not have to retain oil), has a clamp on sleeve, originally without a gasket.
Clamp on sleeve detached
View to the left...
...and to the right
For my second attempt at sealing the chamber, I painted a 2.75" x 11.75" rubberised cork strip with Heldite and wrapped it around the centre section, secured it in place at the top with gaffer tape and tightened the sleeve over it.

And here's what it looks like:
Attempt No. 2 with rubberised cork gasket
The proof of the pudding is in the filling with oil so that's what I did next but initially with an unexpected surprise.
Not so easy to fill; gasket a bit too effective!
Of course, I hadn't thought that the gasket would also be blocking the filler! Undeterred, I tried the hi-tech solution and jabbed it with a screwdriver.
Hi-tech solution...
...Now holding oil
About half a day later, I took this photo:
No leaks this time (after half a day)
So it looks like I've won this time round!

[Postscript: About a week later there was slight leakage - but not enough to worry about!]

Despite my early difficulties here, Sentinel obviously had faith in the method as they were still using it in post-war locos, the latest I've found it on was built in 1958 (Sentinel 9622).

In 2008, I took this picture of William's engine at Elsecar. (Sentinel 9599 built 1956).
William's Oil Chamber Sleeve
The sleeve is up from and to the right of centre. And guess what? It leaks too (unlike the modified 7109 version, attempt 2)!

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