Oil pressure

[Steve A]

Hi, i have been offered a nice car (only seen photo's so far) to buy and asked all the usual questions. The seller has told me that oil pressure when cold is at end of gauge around 100psi and when hot 70 to 80 ? which seems quite high to me? The engine was rebuilt around 6000 miles ago overbored 1310, new pistons and rods etc. I have yet to own a mini where the oil pressure is over 60psi when warm ould this be a problem? what could cause this? thanks Steve (novice mechanic lol)

[Tim]

Problems with the oil pressure relief valve can cause very high oil pressure. There used to be a theory that you could replace the valve plunger with a 1/2" ball bearing from a CV joint to prevent the valve from jamming in its guide. I tried it once and the pressure went stupid, it turns out you need to shorten the spring. Its possible the same has been done to this car.

Tim

[graham in aus]

I had trouble with the spring sticking in the releif valve bore after fitting a ball, I had to use a rod up the centre of the spring, all sorted! See:

http://www.ausmini.com/forums/viewtopic.php?t=58088

[rolesyboy]

Hi Steve. My 1380 which was very carefully built with no mods to relief valve runs 100psi when cold and drops to 60-70 when hot. It does drop to 50 when really hot but to date the engine behaves without a hitch and pulls like a train (outperforms our Golf 1.8 Turbo to about 80mph) I know what you mean re high oil pressure but my feeling is that if it has done 6k and still runs strong I would just give the car a really good run and then pootle around town to see if it does maintain the 70psi when really hot. Bet it doesn't. Good luck. Mark

[YMJ]

Of course, he could be exaggerating the 70-80psi, thinking that this is a good thing and in reality it's really 60-65 psi all along!

[1071 S]

As long as everything is reasonably healthy the oil pressure can be adjusted to wherever you want it.

Using the standard setup just add sump plug washers to taste under the relief valve nut to reduce pressure; add a few smaller washers inside the cap to increase.

I have mine set for a tich over 75 hot (anything over 3K revs) which gives around 30 at hot/idle and about 80 cold .... Using synthetic oil I find engine/outside temp doesn't really affect the reading.

Cheers, Ian