Spring loaded disc in the oil pump base

ratwing

ratwing

Active Member
The oil pressure relief valve on mine is really badly scored and appears to have bits of metal embedded in the bore where the plunger goes - so much so that a new plunger won't go fully home. (The old one won't go back in either, I had to wind it out with a rawlbolt because its so scored and worn)
So I bought a Mocal pump plate with threaded holes for an external filter, not because I want an external filter but because a new base appears to be unobtainable.
Anyway, the plunger/spring fits nicely but in the old pump base there is a barrel-shaped spring and a plastic/tufnol (?) disc held in place by a deep-dished washer but the Mocal base has no provision to fit these, is it a matter of concern that these parts will be missing?
 
ratwing wrote,...
but in the old pump base there is a barrel-shaped spring and a plastic/tufnol (?) disc held in place by a deep-dished washer but the Mocal base has no provision to fit these, is it a matter of concern that these parts will be missing?
Click to expand...

The part that you describe that appears within the original P6B oil pump cover is the bypass valve for the oil filter. The bypass valve and the oil pressure relief valve are not one and the same, each serves a distinct function.

Provided the oil filters that you are going to use come complete with an inbuilt oil filter bypass valve, then you don't need to worry. If you do use a filter that does not have an integral filter bypass valve, then blowing the filter is a very real possiblity :shock:

Ron.
 
Thanks Ron, I'm not sure what the bypass is supposed to do but I wonder why the Mocal base doesn't have one? Time to go to google and see if I can find a seperate one I can plumb in...
 
ratwing wrote,...
Thanks Ron, I'm not sure what the bypass is supposed to do but I wonder why the Mocal base doesn't have one?
Click to expand...

The bypass valve allows oil to bypass the filter in the event that the filter become blocked, or the engine temp and viscocity of the oil are unfavourable in terms of flow at that time.

All oil pump covers for the Rover V8 engine from circa 1977 onwards had the oil filter bypass valve removed, with the filters carrying it instead. This occured at the same time as the reduction in spigot size.
There is no need to worry, just always be sure to source filters with the integral bypass valve. If you ask for a filter for a Range Rover classic, you'll have no problem.

I am of course assuming that the spigot on the Mocul is 3/4".

Ron.
 
Aha, that explains a lot - my Moto Guzzi had an external filter conversion (the standard arrangment had a spin on filter inside the engine so you have to remove the sump to change it!) and I couldn't figure out why the filter kept bursting. I thought it was due to the oil pipes being too small but sounds like the bypass valve was bypassed if you see what I mean.
I've bought some Wix filters for the Rover with a built in bypass so all should be ok now. Thanks, Ian
 
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