Just noticed the needle drop from 50lb (where it always sits) to 25lb when I was sitting at the lights in Barney this arvo. Oil pressure also seems to take a little longer to come up to 50lb at startup. How alarmed should I be?

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http://www.rylstoneclassic.com

When was the oil last changed?

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A recent study found the average Aussie walks about 900 miles a year
Another study found Aussies drink, on average, 22 gallons of alcohol a year
That means, on average, Australians get about 41 miles per gallon

Kind of makes you proud to be an AUSSIE

Yep I'd be changing the oil & Filted

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Stop Licking the Dog...I Don't Care Who Started It

What oil are you using?
25psi at idle is fine, some oils give better pressure when HOT than others.
Castrol Edge Sport 25W/50 = VERY good,
KMart KMX 20W/50 = VERY good,
Penrite HPR30 (for example) not so good.
Castrol GTX... much worse!

The bloke I bought your 1293 motor from said " it has only done 10,000 miles since rebuild by Warwick Agustin" (but that was years ago). It had been standing under cover when we got it.
I stripped the gearbox and fitted new bearings, layshaft, synchros etc.
But all I did to the motor was pull the head, port it a bit, fit Rimflo inlet valves, new guides & seals and recut the valve seats. And I pulled the oil pump for a look and it was fine.
[edit] and I fitted Toyota Corolla rockers for more lift, as the Wade 104 cam doesn't give enough for a warm 1275.

We only did about 5000km in it. It wasn't using oil, which is a good sign all is pretty good internally.

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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.

your lucky the oil pressure in our moke is about 3-4lb

Oil pressure relief valve... it may not be seating properly. Might be reason for sudden drop.

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'68 Morris Mini 1310 A+ (Now Sold!)

It has a 9/16" steel ball and spring. Seats better. No valve...

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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.

It's still a valve though, isn't it?

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'68 Morris Mini 1310 A+ (Now Sold!)

Yeah but the ball is smaller diameter than the plunger was, so it doesn't jam in the bore if any crud finds its way up there.
Also, unlike the plunger, it centres itself in the seat, so it doesn't leak oil past at idle.

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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.

It might be worthwhile cleaning the back of the guage and purging the guage feed line.

My gauge was suddenly inconsistent also.

See details and fix here......

http://www.ausmini.com/forums/viewtopic.php?t=61093&highlight=oil+pressure+gauge

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68 Morris Cooper S Mk1 (*ex 78 1275 LS 4th last built, 70 Morris 1500 OHC & 70 MiniMatic)

The gauge line on this particular car is a long copper pipe, check it hasn't been kinked somewhere. Like, where it goes in behind the gauges...

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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.

Thanks for the input all. I will start applying some of the remedies and see what we come up with. I guess I was just alarmed to see it drop!

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http://www.rylstoneclassic.com

Hi, was wondering how Barney's low oil pressure problem is going?:?:

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'68 Morris Mini 1310 A+ (Now Sold!)

Oil change tomorrow, but it's definitely temp related. I topped it off with some rubbish after a dyno tune. The gauge dropped after I had a bit of a hot run up a freeway link here in Newcastle. Cold to normal, pressure normal. Hot, pressure at idle drops. New oil and filter as recommended by Doc tomorrow and I'm hoping for a return to form.

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http://www.rylstoneclassic.com

I had hot engine and oil pressure drop issues with the 998 climbing the short steep ascents on the Interstate 5 in southern Oregon while on the way "up" to Mt. Shasta in northern California in summer time. Oil cooler fixed that.

Fully loaded (2100 lbs.) for transcontinental trip, 998 pulled strongly over Coquihalla Hwy. and through the Canadian Rockies on trip to Mini Meet East in Quebec with no engine overheating or oil pressure drops.

Stock rad was good for 998, oil cooler was good for pushing the wee beastie over the mountains with big load and in warmer weather (+100F) Oil coolers can be easily blocked off when operating in cooler temps.

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Select a gear, bring up the revs and release the clutch...off you go!