Tuesday, 26 April 2016

Glandular Fervour

In February 2016, when Sentinel 7109 took its first self powered trip in decades, it was clear that there were a few problems. One being that the various glands which seal piston rods and pump plunger shafts have gone hard or have been overtightened in ignorance recently or in the past.

There are 18 of these associated with the two engines and their boiler feed pumps. Some are worse than others, particularly the pump glands which are letting water out and down into the crank cases. Whilst crankcase oil is designed to allow the water to separate out from the oil and be drained, I'm not sure it was designed to cope with gallons of water!

These photos are from April 2009 and show the state as found of the front engine pump glands.
Glands within the pump assembly
There is an upper and lower gland, one should prevent water leaking downwards from the pump, the other to prevent water that did leak from entering the crankcase below.
A bit Rusty?
It's difficult to tell whether the rust had accumulated during use 50 years ago or subsequently.
No better from this angle!
After much restoration, the front engine pump glands are shown operating in this video clip on YouTube. (Sorry, it's too big to include here).

Clearly there is work to do! I took apart the rear engine's upper pump gland and poked in the camera to see how it was.
Rear engine's upper pump gland
The gland material looks pretty hard with a small gap around the plunger. This will have to be dug out and replaced before it will work well. Fortunately the shaft seems to be fairly parallel so it may not need replacing. Anyway, it's easier to try a simple fix before a complicated one so I'll do the packing only to begin with.

I've been recommended greased hemp rather than graphite or PTFE for water pump applications. It needs to be 3/8" square section. Sentinel used to have an off-the-shelf item for this but it doesn't seem to be available any more for some strange reason...!

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