hey guys
found my self with a slight oil pressure problem the other day
the first stop was the oil pressure release valve
undid the bolt only to find the spring came out but not the valve
after 15 min stuffing around with pliers to no avail
i came up with the ultimate remover
a 10mm DYNA Bolt
this worked an absolute treat

just thought this would be a handy tid bit to keep in the back of you minds
should you get a stuck oil presure valve

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A almost Bog Stock 1977 LS
1969 morris mini panel van, a work in progress

Yeah it's a good trick I use too.

Do yourself a favour- as these valves stick:

1. Throw valve as far as possible over left shoulder.
2. Go to a bearing shop and buy a 9/16" steel ball.
3. Cut 4mm off the spring and deburr it. Put cut end outwards when fitting.
4. Cut a piece of 5/16" dia steel rod, 40mm long. Put inside spring.
5. Assemble ball, spring & rod, fit cap. No more problems and better pressure at idle as the ball seats better.

<edit> I've done half a dozen motors with this mod.

NOTE:
The bit of rod is to stop the spring from bending and flicking the ball around as it lifts off seat (which can cause intermittent pressure drop). Don't leave it out! There is 8mm of room in there for ball travel, which is heaps.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

What kind of pressure will 4mm off the spring give maximum (typical conditions)?

The reason for taking 4mm off the spring is, if you don't, the pressure will be 100psi or so. This is because the springs sits ON the ball- it used to sit IN the valve.. so if you don't cut the spring it is compressed too much.

Taking 4mm off spring and using the ball, it will be around 60-70psi (as normal).

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

When i start my car it sits at 65-70psi then as it warms up it will sit around 60psi. If i drive it hard it can drop down to 50psi. The valve wouldnt effect this would it? i think i just need to keep the oil temperature down. Do you think i need an oil cooler?

No, but what the ball does is seal better at idle, and it can't stick if swarf etc gets past it, like the valve can.

I pulled a 1380S down a while back- the valve was jammed, partly open. Didn't help oil pressure at all- he had about 20psi, hot and stuff-all at idle...

<edit> 50psi hot is OK, a cooler will help for highway running or racing. Around town- bugger-all difference.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

my oil pressure is a lot higher than the numbers people usually quote as 'normal' (60-70psi hot cruising). mines usually about 50psi at idle (hot) and about 85-90 cruising. I had thought that high pressure is good, but i've just been reading on the minimania forum that its a waste of hp. maybe it will also explain my oil leak at the pressure release valve??

Anyway at the moment the valve is padded out with a couple of thick washers. If i want to try your ball bearing mod, and also reduce the pressure and also get rid of the extra washers, i'm assuming that i should cut the spring by the thickness of the extra washers + the 4mm that you mentioned + some extra amount to reduce the pressure. how much might that be at a guess? Should i just try 1mm at a time and go the trial and error test..??

Geoff

I'd cut 4mm off the stock spring and try without any washers. If pressure is a bit low, add washers to bring it up.
Mine is about 70-75psi, hot, at 2500 rpm up. And the motor has now been thrashed for 45,000 miles..

I believe in oil pressure, and BMC specified 70psi hot for Coopers.

You have a 3 main bearing crank in there, the middle one has to oil 2 of the big ends. Most newer motors have 5 main bearings and don't need so much.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I'm with Kevin on this one.
It's usually lack of oil pressure thats the problem with Minis.
My Cooper 'S' idles on 50psi and runs on 75-80psi.
It didn't always until I lapped the oil pressure relief valve onto its seat. No more 10-20psi hot idle pressure.
If your into serious racing it may be an advantage to reduce pumping losses in the oil pump but not for road use.

Miniron