hi everyone (including you!)

my mini is travelling well, and i'm absolutely stoked with it. however, it's doing something that i dont know how to remedy.

when the revs are low the oil pressure light comes on, but when the rev count rises again it comes good. but as the revs drop again, light comes on. why?

i think this one is related, i'm getitng a small puff of smoke on startup, but at no other time. i had the plugs out today and there was a tiny amount of oil fouling, but it was mostly carbon.

i've done about 500kms since we changed the head gasket, so today i adjusted the rocker clearances and tightened down the head (cheers scott ballistic for the advice), did the plugs and points and changed the oil (the oil was a milky sludge when we did the gasket, it's why i wanted to get in there.) so if the problem persists, which i assume it will, what do you guys think it might be?

also, i was really lucky we had a spare rocker cover gasket, i broke mine taking the rocker cover off and i didnt know where i was going to get another...

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78 Leyland Mini - Prince

it was sitting for a while between having the head gasket changed after getting water in the oil, and when it was running again, wasn't it?

the small puff on startup is nothing to worry about, just valve guide seals, dropped oil pressure is another issue altogether and I'll let everyone else jump to conclusions about that...

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did I tell you that I won a trophy?

what sort of revs does t idle at Dylan?

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'62 Morris 850 (Marion)
'65 Mini Delux - sleeper 1275/S discs (Ms Plum)
'69 Vanden Plas Princess 1300
'71 Wolseley 1300
'74 Austin 1300 Countryman
'94 XJ6 Sport 3.2
'04 Rover 75 CDTi

yeah about 2 weeks i think, between changing the gasket and when it actually ran.

i've got to have a look at the carby, after i've been driving for a bit (this is when the light comes on, it's fine on start) it idles at around 1500 but 1000 when cold

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78 Leyland Mini - Prince

you can do some things to remedy it in the short term, using thicker oil would be the first thing.

the carby should be a simple adjustment of the idle screw, unless you have a vacuum leak or the throttle shaft is worn

It's possible that you have worn your bearings out in the motor if you've had water in the oil, as water isnt a very good lubricant. The worn out bearings would cause a loss in oil pressure so that at idle its insufficient to turn the light out.

Other people might have other ideas but i would say its quite possible this is the problem

I had the oil light come on in our Clubman, and decided a binary instrument (on=bad, off=good) was a bit archaic so put in an oil pressure gauge. Turned out the oil pressure switch (replaced by the oil pressure gauge sender) was dodgy; the oil pressure is fine. Worthwhile doing as it's a nice bit of information about your engine to have as you drive along.

All of what you describe points towards a worn engine but the good thing is that (to a point) minis cope with it and continue to drive for a long time before reconditioning is necessary.

Minis have a couple of achillies heels in the engine - firstly the oil filter is after the oil pump and therefore grot goes through the engine causing wear before it is filtered out.

Secondly the oil pump itself can become fairly scratched and loses the capacity to pump quantities of oil particularly at lower revs.

Now there are a number of things you can do without great cost or effort and without an engine rebuild. As mentioned, use a thicker oil, change the oil filter and pull out the oil pressure control plunger and spring. If its scored toss it away and fit a new one. Or better still - search for and follow the instructions for fitting a ball brearing instead of the plunger. Its in the "how to's" section. Replace the oil pressure switch - they are cheap and readily available.

Valve guides in the cylinder head do wear and so do the valve guide seals - that allows oil to get into the cylinders and thats why you get a puff of smoke (as Simon said) but its not a worry until you are consistantly getting big puffs of smoke everytime you pull away from the traffic lights.

However, bear in mind that you have a worn engine and treat it with respect. No traffic light derbies etc. You should still get a good couple of years before it really does need some reco work.

Mike

thanks for the tips guys.

i don't know why it is worn though, unless the water in the oil has knackered various bits and pieces, the motor is about 1000-1100 km old...

interestingly, it seems to ahve stopped after i changed the oil (and filter of course) yesterday

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78 Leyland Mini - Prince

Oh I missed that bit !!!! the 1100 km old bit.

Whats was done to it ???

But yes a clogged filter causes the oil to bypass it and that does cause an oil pressure drop.

Mike

a worn oil pump will cause low pressure on an otherwise good engine

As suggested check your oil pressure bypass.

When built, did the person building remember to put in the rubber O ring between the engine block and the gearbox? without that you also get low oil pressure.

IMO if your engine is 1000 miles old, it can't have destroyed itself in such little time unless something catastrophic has occurred.

Lastly if it is a newly rebuilt engine with a second hand oil pump, you should fire your engine builder!!! (cept that is if your engine builder happens to be DrMini or GR, in which case just do as they say I am running a second hand oil pump in mine, steel plated fast flow, 90psi pressure consistently)

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Lillee - 1969 Morris Mini K

problem seems to be rectified, but if it keeps happening i will check the oil pressure bypass.

yeah the o-ring went in, the engine builder made sure of that!

the engine is still young, but when i was running it in it got a little warm which i think damaged the head gasket, which has since been changed (all the usual symptoms were there; water in the oil, bubbles in the radiator, mayo in the oil filler cap...)

not sure of the condition of the pump, i asked my dad/engine builder he said he can't remember. it wasnt a new one

engine goes sounds very healthy (except last night! see other thread...)

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78 Leyland Mini - Prince

ok, so after changing points and going for a spin today, this issue is different...

i think the filter was just clogged up, because the oil pressure light is not flashing at me anymore

but, puff of smoke on start is still there. valve guides?

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78 Leyland Mini - Prince

It will be a combination of worn valve guides and worn guide seals.
But... its a head off and an engineers work to fix it. Its only when you blow noticable lots of smoke at traffic lights that you really need to do something about it. The worn guides is something that minis do and have done since they were first made.

Now, when you do get it done, the machine place will tell you that is needs a full reco. It probably does. Most mini heads warp over time and need a skim to get them flat again. Its also a good idea to have the head acid bathed, valves refaced and the valve seats recut. At that time you could also have hardened exhaust valve seats inserted so you can use unleaded fuel.

All up the cost is about $400 but it really does make a difference to the car.

Mike