Oil light flickers below 800 rpm. Mg 1100

[mg1100guy]

I'm after a bit of advice. When hot my oil light flickers at anything below 800 rpm. I want to change the oil pump but I've never done one on an a series lump before. Could someone run me through it please. Starting with where it is:D
Richard

[Tim]

The oil pump is buried pretty deep. Its on the clutch end of the engine block, driven by the cam shaft. To get to it you have to take the engine out, then remove the clutch cover, pull the flywheel and then remove the alloy casting that forms the end cover for the crankcase and gearbox. After that its easy. While you've mostly got it apart you may as well split the engine and gearbox to check the wear in the main and big end bearings, they're the usual cause of low oil pressure.

Tim

[FCV.66]

Hi,

Have you changed the oil pressure warning light switch yet? A faulty one is often the cause of a flickering light. If your oil pressure really is that low the crank would likely rattle on cold start-up and would rumble when hot.

Garry.

[Dean]

borrow or buy a oil pressure gauge. ( worthing having one fitted) that will tell you what pressure you have and if there is low pressure on not. as said it could be a faulty switch

what level is your oil at , and when was it last changed

[mg1100guy]

Thanks for the replies. The oil gets changed every thousand miles or so. Not rigged up a pressure gauge yet. Don't know why I didn't think of that! The oil pressure switch has also been changed:)
I've got no rumbles or knocks at all. Nothing. And I've blown up my fair share of engines:p

[ianh1968]

I would not necessarily be concerned if the lamp only "flickers"
at 800rpm with hot oil. Temperature makes a lot of difference
in the oil's ability to pressurise, so how hot is hot? Once it gets
above about 85 degrees c, pressure drops frighteningly...

The normal switches operate at 5-7psi, which is quite low, but
the engine is under virtually no load at idle so it doesn't really matter.

I'd still get a gauge to check what it is actually doing, especially
at road speed and under load. On a fairly normal/standard
engine, as long as you have 40psi or more you should be OK.
For a more performance oriented engine, 60-70psi is more
in order.

Have you checked the oil pressure relief valve?

Often when I have had a sudden reduction in oil pressure the
cause has been a tiny spec of crap in the valve. In case you
don't know, it's that 1" AF nut/cover which sits below the banjo
oil output on the block. The nut has a hefty spring behind it, and
behind that the actual "valve".

I once ran an engine for weeks that gave 60psi cold, dropping to
almost ZERO psi on the gauge when hot, at idle. It went for a long
time before the gearbox gave up for a different reason entirely.

Put some "Slick 50" in and you should be OK!

[carbon]

Richard - how long does it take for the oil pressure light to go out when starting the engine from cold (in particular if it has not been used for a week or so)?

If the light takes a long time to go out then chances are the oil pump is well knackered.

If it goes out quickly then it may not be the oil pump at fault.

[mg1100guy]

Hmm I havnt checked the oil pressure relief valve. If I start it from cold in the mornings with full choke the light takes around 2-3 seconds to go out. If it's been a week or so it's maybe a second longer but not much. I'm going to put a pressure gauge in this week to see where I stand:D and some slick 50 aswel:D

[underkut]

I may be wrong but does the mg1100 also have the oil filter change sensor?
If that uses the same warning lamp that sensor could be faulty

[mk1]

Personally speaking I would not worry about a flickering oil pressure warning light at 800 rpm when hot.

If you notice the periods it comes on start to increase then I would start to think about investigating further.

M

[Spider]

Personally speaking I would not worry about a flickering oil pressure warning light at 800 rpm when hot.

If you notice the periods it comes on start to increase then I would start to think about investigating further.

M

+1 and forget the slick 50.

[mk1]

and forget the slick 50.

Ditto, I have only ever had 1 engine totally let go, it was the only one that I "treated" with Slick50.

I didn't know they still made the stuff.

M

[ianh1968]

and forget the slick 50.

.. It was a bit of a "tongue-in-cheek" remark, but I do use it.

Many years ago I had a straight cut 3 synchro box and the Slick 50
made a considerable improvement/reduction on the amount of noise
that came from the drive train. On that basis alone, I use it.

So far as the power claims are concerned, I very much doubt that
anyone has obtained any genuine before/after data, so I would be
inclined to discount this entirely.

I would like to think that the stuff does do what it says on the tin,
as far as lubrication is concerned, but who knows...

Ian