Background: my BJ8 has run low oil pressure at idle for as long as I've had it.
At startup I get 60psi, but after
running on hot days I would register, for all intents and purposes, zero psi at
idle. In spite of this, the engine has
run and performed well for me for over 100K miles. I use 20W-50 dino oil.
There has been a lot of discussion on the BCF about replacement relief valve
springs being shorter than spec. It has
been suggested that putting washers or other shims or a 1/4-inch bolt behind
the spring could increase running
pressure. I actually didn't believe it because AFAIK the valve is there to
keep pressure from getting too high, and
presumably would be fully closed at normal running pressure. But, I was
curious ...
So today I pulled the relief valve and measured the spring at 2 & 11/32"; quite
a bit less than 'spec.' So I installed
the 1/4-inch bolt and fired her up; 70psi on cold start/fast idle--not too
surprising. What's surprising is even after
the engine has warmed-up--when I would normally see 10-20psi, before a long run
in hot weather--I am getting 40psi. And
the max pressure is still at 70psi; so the effect is max pressure is up 10psi,
but the hot idle pressure could be up
10-20psi!
My questions to the forum are: is 70psi too high a max oil pressure? Any
explanations for this phenomenon? Should I
split the difference with some shims? Go back to the spring-only setup so I
can sleep?
Bob
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Bob Spidell San Jose, CA bspidell at comcast.net
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