Amigos,
Here is a practical problem to divert us from the ongoing legal debate:
I have an oil pressure problem in my fresh TR6 engine that is limiting the
pressure to 50 psi max. I suspected the oil pump and in the process of
replacing it decided to test the pressure relief valve that unseats and dumps
oil back to the suction side. I don't know if this is a common design but it
consists of a plunger under spring pressure that seals off the return passage
from the main gallery.
The only way I could test it (engine in the car with oil pan and pump removed)
was to apply air pressure to the return port in the block, which is the
reverse of the actual relief valve flow in operation. I did this and was able
to detect slight air leakage back into the main gallery through the bypass
valve. If it leaks in this direction it will surely be as bad or worse with
actual pressure working to unseat the valve. I now think my oil pump was okay
after all (no threat of libel lawsuit, I worked on the pump myself).
Some important background: When I built the engine I replaced the stock
plunger with a part I made in our machine shop because the original was worn
on the shaft. I reamed the housing to the new shaft size and made the 'head'
thicker to effectively shim the spring. I also bought the stronger spring from
Moss but did not use it. I suspect that I have screwed this up somehow (not
the first time but I can't resist trying to 'improve' things when I have them
apart). What I don't understand is that I lapped the new plunger into the
block with coarse grinding compound and I do see a witness mark all the way
around. The lapping mark isn't as deep as I would like as it is hard to rotate
the plunger to lap it in, but I am sure the angle and concentricity of the
sealing suface is good.
My options that I can see:
1. lap it some more
2. put in a stock plunger and housing
3. Pull the motor and recut the seat $$$$
4. Plug the return port, pipe the return flow out of the side of the block to
an external relief valve and into the oil pan
5. Hope someone in FOT has seen this before and can help me before the event
next weekend!
Anybody out there have any experience with this, Kas, anyone?
Mark
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