Author Topic: Where's the Oils Pressure Relief Valve Gone ?  (Read 1269 times)

Offline awemawson

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Where's the Oils Pressure Relief Valve Gone ?
« on: May 22, 2016, 11:41:31 AM »
I loaded the Thwaites dumper truck up with chestnut fencing stakes, and set off towards a distant field where I was fencing. As I stopped to open the gate I noticed a rapidly growing oil slick underneath, and oil was gushing from the hole where the oil pressure relief valve should be  :bugeye:

No real trail of oil behind me, but no signs of the missing components either :bang:

A quick look at the parts book revealed very little - they just show the whole assembly
Andrew Mawson
East Sussex

Offline awemawson

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Re: Where's the Oils Pressure Relief Valve Gone ?
« Reply #1 on: May 22, 2016, 11:46:16 AM »
Now fortunately the body of that assembly was still in place, and unscrewing it I deduced that it must have a plunger to block the inner orifice, a compression spring, and an adjusting bolt with locking nut. Absolutely no idea what sort of strength the spring needed to be, but in the event the choice was very limited in my spring box.

Internal thread turned out to be 1/4" BSP / 19 tpi so I steamed up the lathe and set too and made these:
Andrew Mawson
East Sussex

Offline awemawson

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Re: Where's the Oils Pressure Relief Valve Gone ?
« Reply #2 on: May 22, 2016, 11:53:09 AM »
But the great unknown - what pressure would it open at? Indeed would it open at all?

Well the owners manual say minimum oil pressure should be 2.4 bar - so I reckoned that if I could set it to 40 psi I should be good to go - but how to set it when there is no easy way to put a pressure gauge on the engine?

I hit on the idea of using compressed air - the body outer thread turned out to be 3/8" BSP so I furtled about in my plumbing bits and found enough to cobble it on the the air feed I'd installed on the Beaver Partsmaster 4th axis brake, as it has a convenient regulator and gauge.

Set it to open at 40 psi, locked it up and fitted it
Andrew Mawson
East Sussex

Offline awemawson

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Re: Where's the Oils Pressure Relief Valve Gone ?
« Reply #3 on: May 22, 2016, 11:57:07 AM »
Topped up the oil (a LOT of oil  :bang: ) and got back to delivering fence posts and knocking them in  :clap:

All seems well, though it would be nice to know what pressure the pump is delivering - though I suspect that the engine is probably pretty tolerant of abuse  :scratch:


So how the heck do people manage when they don't have workshops ?
Andrew Mawson
East Sussex

Offline PekkaNF

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Re: Where's the Oils Pressure Relief Valve Gone ?
« Reply #4 on: May 23, 2016, 02:22:23 AM »
....
So how the heck do people manage when they don't have workshops ?

Showel in begabucks and buy completely new assembly; or -with a reckless abandon.



Pekka