oil light

[benno]

the oil light keeps coming on at low revs or when stationary. whats up?

[Kevin]

Low oil pressure or posibly a weak oile pressure relief valve, are there any other symptomsor noises at all.

[bmcecosse]

Low oil level ? Oil too thin - use 20W50. Blocked oil filter. Engine worn. As long as it goes out when you revup = don't worry about it - but do consider oil and filter change.

[chickenjohn]

One thing that caught out a friend of mine- the oil light kept coming on at idle- and his traveller was immaculately restored and with a recent re-built engine.

The cause? The wires to oil light and charge light were the wrong way round behind the dash!

Just an additional possibillity to the good avdvice above.

[Willie]

It is very common for the actual oil light sender switch to go faulty so,if you
are satisfied that the engine oil and the filter are not the problem I would change the switch(behind the distributor) as a first step assuming that you are
not using a 'thin' multigrade oil. 'Coming on at low revs' is a bit more ominous than 'on tickover' though!

[bmcecosse]

The real answer is to fit an oil pressure gauge - it's the only additional gauge you really need - then you will know what's wrong! Switch (in my experience) tends to either work or not work - ie the light never goes out but from the gauge you can see there is plenty pressure. But - if you have a spare by all means try it!

[Willie]

I second that, the most useful indicator you will ever fit.

[rayofleamington]

- ie the light never goes out but from the gauge you can see there is plenty pressure.

thats because the light is there to show that filter is blocked, (not the pickup pipe). The blocked filter prevents the important bits of engine getting any oil.
An oil pressure guage does not show the problem of a blocked filter - it merely shows the pressure coming from the oil pump, (ie not the pressure reaching the engine).

[Packedup]

Isn't there a bypass for when the filter blocks up? Always thought there was, but maybe that's only the later spin on type?

[bmcecosse]

The early filters also by-pass - the flat plate is pushed away from the paper element to allow oil through. The second oil light shows the blockage - comes on if blocked, but is NOT on when switching on Ign. The main oil pressure light should go out when running - but switches do fail and my experience is that they fail ON all the time even though there is pressure in the engine. Yes - the oil pressure switch and gauge connections are before the filter - so blocked filter may actually result in higher than normal apparent pressure. But surely no-one on here mal-treats their car so badly that the filter gets blocked!!

[rayofleamington]

But surely no-one on here mal-treats their car so badly that the filter gets blocked!!

I had it on a 1275 engine ~400 miles after changing the oil and filter.
The filter was quite expensive (from ### Minor centre) and had very fine holes in the outer tube. The MG engine didn't have a filter blocked warning light so the first I knew about it was the noise from damaged big ends
This was very dissapointing as I'd not used the engine before hand - I just fitted it, changed the oil and filter and had 2 weeks of fun driving it.

Ever since then I'm wary of the filters that have small holes in the outer tube and if/when one of those comes in a service kit I cut twice as many extra holes. Obviously the main source of the problem was lack of proper servicing by the previous owner, but even now (10 years later) it is still a painful memory.