Oil pressure check

[andrew.searston]

Hi everyone
I have just fully build a 1098 morris engine with 1275 head, having no oil gauge i bought one in temperary placement of the oil pressure switch just to check when i start it. Its between 45 and 50 psi at idle when upto temperature. Is this a good reading?
Thanks
Andy

[Nickol]

I installed an oil pressure gauge only yesterday and running at idle those are also the readings I got - with engine cold.

[andrew.searston]

Is it a good reading for when hot?

[Budgie]

My 1098 runs at 45 psi when hot and idle if that's any help.

[oliver90owner]

The low oil pressure warning light would come on at around 5-7psi? That should answer your question?

[Boomlander]

Anything above 20psi at idle is fine.

[dalebrignall]

thats pretty much perfect

[andrew.searston]

Awsome, now i know my oil pressure is good. The light on the dash glows on, dims down slighty after start up. There was a wire on the oil filter housing ive now changed for spin on type so the wire goes to nothing, is this the problem or faulty oil pressure switch

[biomed32uk]

The oil pressure is perfect, thats what I get at hot idle after a hard run, so good and hot. 75 when cold as you would expect.

The wire that comes off the old filter housing does nothing, one day I will find a use for it but it goes to the bulb at 9 o'clock in the speedometer.

If its glowing dim after start up it may be that the ignition and oil pressure lights have got mixed up in the back of the speedometer, as they will fit anywhere. If you pull the wire off of the oil pressure switch with the ignition on, but the engine not running one should go out, thats the oil pressure one.

A dim glow after startup sounds very typical of the ignition light, going right out when engine speed rises.

Just a thought.

[liammonty]

The wire that comes off the old filter housing does nothing, one day I will find a use for it but it goes to the bulb at 9 o'clock in the speedometer.

That's not actually right on the later 1098 models, for a period, there was a blocked oil filter warning light. I believe these were deleted on the final models as they were unreliable. So, if the car in question has it fitted, perhaps disconnecting the wire to the oil filter has caused the light to come on? If it's in the correct position in the speedo, it's the orange one on the left - oil pressure warning should be on the right, though as said, it's possible the bulb holders have been put in the wrong positions!

[andrew.searston]

Its the orange light on the right of the speedo. If i disconnect oil pressure switch it goes out with just ignition on

[liammonty]

In that case, if the oil pressure readings are as good as you've said, I'd start by replacing the pressure switch, as it sounds as though it's faulty.

[biomed32uk]

The wire that comes off the old filter housing does nothing, one day I will find a use for it but it goes to the bulb at 9 o'clock in the speedometer.

That's not actually right on the later 1098 models, for a period, there was a blocked oil filter warning light. I believe these were deleted on the final models as they were unreliable. So, if the car in question has it fitted, perhaps disconnecting the wire to the oil filter has caused the light to come on? If it's in the correct position in the speedo, it's the orange one on the left - oil pressure warning should be on the right, though as said, it's possible the bulb holders have been put in the wrong positions!

My bad grammar there, should have gone along the lines of when you do the spin on conversion it does nothing afterwards, it begs for use a choke warning light or something, one day when I am bored I will have a bash at sorting it.

[andrew.searston]

All sorted now, turns out to be just a faulty pressure sensor

[liammonty]

Good news! Glad it's sorted.

Biomed32UK - choke warning light would be a great use for the spare warning light!

[MikeNash]

Andy,
Just downloaded and printed the "Morris Minor Workshop Manual" from the web (thank you Mr Islip Minor! - look for the "fishy" address) and at Section AA.4, page legend "Morris Minor. Issue 3. 54936" it says that for the Series II engine

"Under normal running conditions the oil pressure should not drop below 40 psi on the gauge at normal roads speeds, whilst approximately 20p psi should be shown when the engine is idling".

Later, it adds
"New engines with new oil will give considerably higher pressure readings than those given [above]".

Of course, without a declared oil viscosity and temperature, readings of oil pressure can mean all sorts of things, but I've found that on a worn 1098 engine (1966 Gold Seal replacement) in its 38th year at anything over 40mph I'd get 42 psi using Wilkinson's 20-50 oil even when it's temp was 90C and it would cruise happily at 60-65 mph (true) all day without distress or rattles. (But it drank oil!) At the same temp at idle it would have 6-8 psi. But the idle speed is very influential; these days I like a low idle and at 500 rpm with a new and good condition engine the pressure is only 15psi when the oil is quite cool at 60C.

Finally, many seem to be keen to achieve the 60 psi at which the relief pressure valve operates and which, of course, almost any engine will do if revved when the oil is cold and thick enough. Indeed, although my relief valve opens at 58psi I can get 70 psi when the engine's cold. (Out of my drive onto the A343 its full throttle up a hill either way.) However, remember that at 60 psi or more a lot of oil is being dumped and NOT going around the engine. That would be a case for a thinner oil or an oil heater!
Regards, MikeN.

[Nickol]

In the same AA4 section of the Manual it says under §3 that a cause of a drop in oil pressure may be caused by a blocked strainer in the sump.

Is this strainer in place for all models as depicted in section AA.2? The old side valve engines which do not have an oil filter use this component , but for the newer engines with a filter ???? Surely it would then be superfluous?

[MikeNash]

Nickol,
Not sure if it's there in the 1098 but generally the role of such strainers is to protect the pump from relatively large pieces that may arise from within the engine itself such as bits off split pins, nuts off bolts, broken bits of piston ring, etc which would turn a declining engine into an instant failure by killing the oil pump. My 1935 Oxford has a huge "tea strainer" covering the entire sump and in the days before detergent oils large pieces of carbon would be caught on it.
Regards, MikeN.

[irmscher]

Always best to use a magnetic sump plug

[Nickol]

Yes Mike, my Austin of 47 vintage also had this strainer in the sump. I took the sump off last year to check if it needed cleaning - it did not but the sump tray itself was coated in the gunge so the exercise was not wasted. I did take the strainer off any way and cleaned it up, but it did not really Need it.