Ausmini
It is currently Fri Mar 29, 2024 8:22 am

All times are UTC + 10 hours




Forum locked This topic is locked, you cannot edit posts or make further replies.  [ 1 post ] 
Author Message
PostPosted: Tue Oct 20, 2009 12:39 pm 
Offline
ausmini admin
ausmini admin
User avatar

Joined: Sun Sep 23, 2007 6:12 pm
Posts: 246
Location: Under the bonnet
Many Thanks To drmini in aust for this how-to on replacing a scored oil pressure relief valve with a more reliable option.

Fitting a ball in place of the valve will:
1. give better pressure at idle when hot,
2. avoid getting jammed with swarf (like the valve does) if any gets picked up.
NOTE, the Cooper S did NOT have a ball fitted as standard. It is a competition modification.


Here's how you do it.

1. Undo the hex cap, remove the spring and old relief valve plunger.
(If plunger won't come out, put a 10mm OD dynabolt inside it and tighten its nut gently, then pull out.)

2. Get a 9/16" steel ball from a bearing shop, or out of an old Mini CV.

3. Cut 3 - 4mm off one end of the spring. Grind it flat.

4. Cut a piece of 5/16" or 8.0mm unthreaded steel rod (off a long bolt is OK) 40mm long. Put it inside the spring. Make sure it can slide.

5. Put the ball in the block, fit the spring (and rod) with the cut end of spring outwards.

6. Fit the hex cap.

7. Check oil pressure, it should be (with a good motor) around 60+ psi hot, at 3000 rpm up.
You can adjust this a bit if too low, by putting some 3/16" (5mm) flat washers inside the hex cap. If pressure is too high, grind a little more off the cut end of the spring.


The steel rod is to keep the spring straight- if it bends, it can slip around the ball, which then won't seat properly.
At 40mm long there is still room for the ball to lift 6mm off the seat, which is heaps more than needed.

Note:
If the old relief valve plunger is badly scored or out of round, it should be replaced.
If you decide to fit a new plunger instead of doing this ball mod, ensure the new one moves freely in the block without sticking.


Top
 Profile  
 
Display posts from previous:  Sort by  
Forum locked This topic is locked, you cannot edit posts or make further replies.  [ 1 post ] 

All times are UTC + 10 hours


Who is online

Users browsing this forum: No registered users and 12 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  

© 2016 Ausmini. All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.