Oil warning light!!!

I have a 1973 Series 3 2.25 petrol Landy. Done quite a lot of heavy work over the past couple of weeks (towing & carrying loads). Noticed the oil pressure warning light has been flickering & coming on at lower revs over the last week. Checked oil & it is the correct level & relatively fresh. Engine temperature is staying cool.Any thoughts would be appreciated.
Cheers,
Gunwennap.

Check the sending unit. Check the connection at the sending unit (on my petrol, it is located at the top of the oil filter). Check the wire where they connect...are the corroded? are they loose? Check as far back as you can, (back to the light in the dash preferably if possible) for loose or broken insulation, loose connections to brass connectors at each end...in other words any place where there can be a short. Shorts behave like the scenario you described...flickering on and off as the wire makes a ground. This of course could be a dying sending switch...but they typically do not die that way...loose wires and connectors on the other hand do behave in this fashion. If you don't find anything very apparent then clean the brass connections at both ends and re sqeeze the female clasps to insure a secure contact and see if it persists.

Thanks IHMS. I'll try these things and let you know.

Gunny,
I was thinking last night before I drifted off to sleep about your description of the light also coming on when the engine idled very low. That can be telling. First, does your engine tend to idle rough and uneven at lower rpms? If so the increased vibration is making the contact wires shake and that may be where we will find the problem. However, I had a truck show and oil warning light when the rpms dropped low and it was not due to the sending switch or wires. Our engines employ a gear pump located in the lower part of our engine that is driven off the cam shaft and pulls oil up out of the oil pan. The short of it is, there is a direct correlation between engine oil pressure and the gear pump that sends the oil through the motor and the speed at which the gear pump driven. Theoretically, if the rpms drop low enough, the preset pressure sensitivity built into the sending unit will get a reading that is too low for safe operation, and hence a brief blip of the light shows up on your dash. The gear pumps are theoretically designed to pump above what is necessary for safe operation at factory low rpm setting. But in the real world, rpms can drop lower due to old carburetors, bad fuel, loose and warn parts. Thats why you probably have heard the old adage that engines experience their most severe wear at start up when the oil pump has not yet had time to push oil pressures up to safe operating levels. On my Harley, the oil warning light stays on for a very nervous 5 seconds or so at startup. To make a long story short, I was going to also ask the age of the engine (the oil gear pump could be showing some wear) secondly, how old is the engine? When did you last change the oil (has it thinned some) and what weight oil did you use? Was it a 5w-30? I run a 20w-50 in my old 2.25 Petrol because frankly, its a loose motor after 40 years of wear. Finally set your idle a little higher so it doesnt drop too too low.

might be worth lashing up temporarily if necessary an oil press guage so you can see whats going on.
The light flickering at idle is something that an old engine can do, the pump cannot keep up with the volume as the bearing surfaces are worn and passing lots of oil back to the sump, dropping the available pressure.
I have know the wire to the sender to wear through causing the same issue, to check for this disconnect it at the sender and tape it up, it should stay off, if it still flickers then a short is the issue, bear in mind when doing this you'll have no warning if the pressure really does drop.

Thanks IHMS(sorry for keeping you awake!) & Dr.Pepper. First thing I will look at is the wire connections. If that's not it then I will give it an oil change using a thicker oil to maybe hold more at the top of the engine. I will also increase the idling speed a bit. I think the engine is the original & so being a 1973 probably done loads of miles! The oil was changed only a couple of months ago but has done a lot of work since. Are there many old Landrovers in Thailand?

An original or quality oil filter is also reccomended, I've had trouble with crap ones on a couple of vehicles.

My brother's old petrol used to do the same on tick over , just tweeked up the tickover a bit ran fine after that with no knocking . ( not saying that is the case for yours tho but IHMS covers that anyway . )


.

No problem Gunny,
If I told you how many Series Land Rovers there were in Thailand, you wouldnt believe me...and the kicker is they are rust free! The frames and bulkheads are mint!! No salt and the clay soil here just preserves everything. In fact, I am thinking about opening a restoration business for jeeps and Rovers. The jeeps are all Willy's High Hoods...after WWII the US Gov. gave Mitsubishi the rights to build jeeps for our friends in Asia (i.e. Thailand) and they are spot on replicas except for the Three Diamond emblem embossed on the grill. Everything is is identical. I even found a few International Harvester Scouts...but the real treasure chest is Rovers. The Brits set up shop here REAL early and they were the premiere 4x4 for the last 5 decades. The King of Thailand has a fleet of Series five doors~ most however were used up country during the great timber harvesting boom in the sixties and seventies. Now Thailand is largely deforested and imports most of its wood products. No self control and no laws governing replanting. I would cater mostly to wealthy retired Brits or Europeans who yearn for some fresh air and are fed up with their wives making them spend the rest of their lives driving a sensible Honda or Toyota.