Author Topic: Stubbon leaks  (Read 1204 times)

Offline a101960

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Stubbon leaks
« on: 26.09. 2008 21:26 »
There are several little annoying things that I have been trying to get sorted out, so I thought I would present them here to see if anyone else had had similar experiences and if they had, how did they resolve them.

Item one: The SRM sump plate. I have tried all manner of washers (copper, aluminium, and fibre etc) behind the drain plug, but no matter what I do it resolutely insists on weeping. It is not a major leak, but the fact of the matter is, it does not seal. I am loathe to use a sealant on the thread or any where else for obvious reasons. Has anyone else had this problem?

Item two: Again a sealing problem. The primary chain case filler cap. I removed the fibre washer and substituted an "O" ring. It has improved matters, but it still weeps. The loss is not great but every time I use the bike I get a trace running down the case and it makes a stain and undoes all the hard work that I have put into polishing the case. It's not the end of the world but it is a nuisance.

Item three: The RGS petrol cap. When the tank is full, petrol always seems to find it's way past the cap seal. I removed the original rubber one because due the ethanol that is being added to petrol these days it swelled up and distorted before finally perishing altogether. I made a cork gasket as a replacement for the rotted out original item. Is no better or no worse than the original in sealing the petrol cap, but I could without petrol running on to my paintwork. Because I clean the tank after every time I use the bike, so far, there is no staining, but I fear that it is only going to be a matter of time. This modern petrol really is horrible stuff.

Item four: a slight oil weep from the from the pressure relief valve fibre washer. Again this is not a large leak, but over the period of a fortnight or so it becomes quite noticeable.

Generally the engine is oil tight. The Rocker cover and tappet inspection covers do not leak. The rocker spindle banjo unions are dry as is the timing cover and crank case joints. Anybody got any ideas? especially about that sump drain plug!

Offline a10gf

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Re: Stubbon leaks
« Reply #1 on: 28.09. 2008 09:30 »
Hello, some suggestions that may help.

I have the SRM sump, very nice device (though I'd prefer studs instead of the allen bolts, to avoid any possible thread damage to the crankcase when dismantling to clean the mesh). I use a quite thick copper washer, annealed to make sure it's soft before every fitting, no leaks there.

The chain case cap, had the same small oil trace, I made my own washer from some semi-soft gasket sheet, then tighten as hard as I can by hand, then use a suitable large plier for a little extra tightening force (without damaging the alu knots on the cap).

The tank cap, try with some thicker cork ? Cut it from a quality petrol proof cork\rubber sheet. May be tight in the beginning but will compress.

The relief valve used to have some leaks when using the red fibre washers. Not that often this is dismantled, blue loctite will get it 100% leakproof, with minimal need for tightening, and easy to disassemble when needed. I use the dome valve, with homemade thin washers and a very tiny dose of the blue loctite on just a few of the threads.

Good luck.
e

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Offline a101960

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Re: Stubbon leaks
« Reply #2 on: 28.09. 2008 16:31 »
Thank you for your advice. I shall work my way round the engine and do as you have suggested. Do you know the socket size for removing the pressure relief valve?

Offline dpaddock

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Re: Stubbon leaks
« Reply #3 on: 06.10. 2008 20:46 »
The Oil release valve body is 1-1/8" hex (11/16" BS); the body plug is 13/16" hex (7/16" W - same as spark plugs).
David
David
'57 Spitfire