Oil pressure relief valve

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74JohnPlayer

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Sep 2, 2010
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Need some help here. My pressure relief valve was stuck closed. Removed all the parts, cleaned everything up, and reassembled with a new spring. There's no pressure on the spring. All the parts rattle around in the holder. The parts book shows 5 shims in the holder with the cup and spring, but only one is in mine. I know the blow off pressure was set at the factory, but what do you do if you have to rebuild one of these valves afterward? Should I just install enough shims to take out the slack space, or what?

Thanks,

Stu O

Edit - I found the old thread here. Thanks anyways.
 
Mick Hemmings in his DVD puts in 3-2 washers. If it doesn't rattle in the assembly, it is too many. He puts in just enough shims/washers so there is just a bit of rattle when assembled.

Dave
69S
 
ludwig said:
With help of a compressor and an adjustable manometer , you can set it up to the desired opening pressure .
If you want , I can post a picture ( tomorrow ) .
Click to expand...
That should be interesting. Thanks.

Stu
 
Im sure that you quoted Mick correctly, but if the thing rattles it isn't sealing and if that be the case you won't develop much OP, not that you need it. On my Mk III I purchased a new spring and stretched it a good 3-4mm, my Pace Engineering mechanical gauge hits 60 cold and settles down to 40, unless it's very hot (ambient temp). A while back Jim Comstock talked about a major re-do of his oil pump and mentioned that he was getting consistent pressure readings over 80, IIRC. So the Commando can stand a higher pressure, but it can also function with much less.

RS
 
RoadScholar said:
but if the thing rattles it isn't sealing and if that be the case you won't develop much OP, not that you need it.
Click to expand...

It doesn't need to seal in that way, because the OPRV piston will never be completely seated when the engine is making oil pressure, the OPRV relies on the close fit between piston and the body for its seal.




RoadScholar said:
On my Mk III I purchased a new spring and stretched it a good 3-4mm, my Pace Engineering mechanical gauge hits 60 cold and settles down to 40, unless it's very hot (ambient temp).
Click to expand...

Usually shims are added to adjust blow-off pressure.
 
Hi all.
I used a timing cover that has been cut up for camshaft nut removal. I removed the blanking plug over the OPRV inside the cover then cut threads in the oil passage to the crank seal to suit the blanking plug
then screwed the plug in to seal the oil passage up.then screwed a grease nipple in to the hole I removed the blanking plug from.Then fixed an oil pressure gauge to the rocker shaft outlet ,filled a grease with
engine oil attach to the grease nipple and pump up to pressurise the OPRV and see on the gauge when the valve blows oil out of other oil way in the cover.Took longer to write than to do. !!!!!
 
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