Morris Minor Owners Club

This has just started coming on, the engine sounds no different to normal.

Start the car up and the light goes out, lift the revs slightly and it comes on but if you keep putting your foot down it goes out again

As long as the oil pressure light goes out when you increase the revs then it is probably OK, just increase the tickover speed slightly. If you want to worry about the oil pressure then fit a gauge

mike.perry wrote:As long as the oil pressure light goes out when you increase the revs then it is probably OK, just increase the tickover speed slightly.

Well I increased the tickover slightly, but that didn't do much.

Another symptom that might help - The oil pressure is out when doing 30mph in 3rd but soon as I change to 4th it comes on

That sounds like my engine, I am listening for the bearings to start knocking and keeping an eye on the oil pressure gauge.

Matt,

Is the oil level correct? When was the oil last changed, and what grade?

is the wire still attached to the switch? my wire broke off and the light would come on and go off at odd moments whenever the end of the wire earthed on something!

or the switch could be packing up. i agree with the suggestion of fitting a gauge, far more reliable than the light!

IslipMinor wrote:Matt,

Is the oil level correct? When was the oil last changed, and what grade?

Level is correct, 20w50 oil.

chrisryder wrote:i agree with the suggestion of fitting a gauge, far more reliable than the light

Something I've been meaning to do since I've had the car

Does the light come on more readily when the engine is warm? That would be a sure indicator of a worn bottom end (the same happened to me a few years ago).

First thing is to replace the switch and see what happens. The switch is cheap, readily available, and easy to fit. If the symptoms persist then you have a problem brewing. If the symptoms disappear then all is well and good. Far better to know than to wonder!

Assuming sufficient oil - it could be stuck relief valve (i've just been dealing with a very sad case on mini forum where I suspect a lad has ruined his fresh build 1380 with this........) - check it urgently - don't run the engine until you have done so. An oil pressure gauge is a MUST - I suggest you rig one up urgently - even temporarily - so you KNOW what's going on. It 'may' be a dodgy pressure switch - but the symptoms suggest stuck relief valve to me............

bmcecosse wrote:but the symptoms suggest stuck relief valve to me

How do I unstuck it?

I had this issue just before christmas on the blue minor, a new switch sorted it out no problem. Try that first they only cost about £4.00 and are easy to change

OK... maybe a stupid question but where am I looking for this?

mine is on a T piece coz i have a gauge fitted too, but its in the same place, but straight into the block

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Cheers Chris, I shall take a look tomorrow!

Undo the cover nut for the relief valve (1" AF I think) - remove the spring and the valve body should slide out on the end of your finger. If not the wood shaft of a valve grinding tool is often a good fit - stick it in and wiggle it until the valve comes out. Clean everything and refit. Then crank the engine up on the starter with plugs out to check you have good (~60 psi) pressure before attempting to start the engine.

Here's a close up of the pressure switch fitted to the T-piece. The brass fitting is for the pressure gauge.
Regards
Declan[frame][/frame][frame][/frame]

I've got the pressure switch off no problem. Having problems with the relief valve, I don't seem to have anything that will fit it. Looking at the way it has been done up (the angle the flats are at) it may require the dizzy to come out to get at it properly - something I'm loathed to do myself as I'm sure I'll just make more problems for myself

I'd love to meet the 'eedjit' who designed the relief valve nut size. Near impossible to get a socket on it since it is so close to the backplate, so, probably worth welding a smaller nut to the topso you can get it back on more easily?
I had to remove the entire engine from the Lenham Sprite to get the backplate off (removed the flywheel, too) due to the lack of room to get anything in there.

Cleaned up the old pressure switch and re-fitted it which did nothing. But when I removed it I could see it was covered in oil again, so it was leaking.

Changed it for a new one and now the light stays out... happy days