[Healeys] Pressure relief valve

Bob Spidell bspidell at comcast.net
Sat Apr 30 22:08:34 MDT 2011


I put the bolt inside the end of the spring--basically using the bolt head as a shim (about 1/8" thick).

Bob


On 4/30/2011 8:44 PM, Mark LaPierre wrote:
> You lost me Bob?
>
> Where did you install a 1/4 inch bolt?
>
> Mark
>
>
>
>> 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
>>
>> -- 
>> *******************************************************************
>> Bob Spidell           San Jose, CA            bspidell at comcast.net
>>
>> *******************************************************************
>>
>
>


-- 
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Bob Spidell           San Jose, CA            bspidell at comcast.net

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