Low oil pressure when idling

[Paulfrazer]

I have read several threads on low oil pressure but I wonder whether anyone can advise me about it. I bought the car last summer and I have to say it is far from what I hoped it would be. Anyway, after lots of work it is becoming useable (I hope!). The next problem is that the oil warning light comes on at idle when the engine is hot. I hoped it would just be the old oil but having replaced the filter and the oil with the recommended Valvoline the light still come on. It has covered an indicated 70,000 miles which looks right by the "patina" on the interior, pedal rubbers, carpets etc. My previous classic was a 160, 000 mile Rover P4. The oil warning light would flicker slightly at idle if it was very hot but I could forgive that in the old lady!

My first thought is to replace the pressure switch (and maybe fit a gauge at the same time) but I would like advice from those more experienced for a systematic approach rather than trying things on an ad hoc basis.

Thanks in advance

Paul

[richardthestag]

Hi Paul

First, don't panic! You could have a false positive which would be a dodgy oil pressure sender. Your approach is perfect, cheapest check first.

Next UK valvoline has become a contentious one because they are not confirming the zddp content as they are in other countries.

I prefer this https://www.classic-oils.net/Classic...Heritage-20W50

Next what kind of filter are you using? spin on disposable or original cartridge? if cartridge be sure that the top of the filter is sprung and will be pressed up against the block when installed.

Regarding oil pressure gauges, fabulous diagnostic tool, but unless you understand what it is telling you it is just another distraction on the dash.

If I were you I would swap out the oil pressure sender first, as you already suggested, but with a good quality item, then would ask a friendly mechanic to check the oil pressure. If the pressure is low then I would be checking out the oil pump.

Not uncommon on a Rover v8 for the oil pressure light to flicker at hot idle on a hot day and when ready for an oil change. no disaster. However design of the stag engine is such that the chains are tensioned by oil pressure, should the pressure be too low and the chains at the end of their life then catastrophe may occur.

Stay sane, your approach is a good and sound one

[Paulfrazer]

Thanks Richard. It takes an original cartridge which fitted well against the spring pressure. As an aside I don't know why some chose to replace them with the spin off type, I had no problem changing mine. Anyway, I will get a new sender unit and report back.

Thank you

Paul

[DMT]

Paul, you don't actually say but I assume you have an oil pressure gauge. At what pressure did the light come on.

Dave

[Paulfrazer]

Hi Dave. No I don't have one. I was going to get one at a later date and replace the volt meter with it.

[DMT]

I have the manual oil pressure gauge, but some use the oil pressure/water temp dual gauge in place of the water temp and keep the clock.
Dave

[Paulfrazer]

I think I am happy to lose the volt meter to be honest. I am not really sure how much use it is. The clock actually works!

[richardthestag]

My vomiter was quite useful on 2 separate occasions. Both times I had a regulator fault in the alternator, first was it only putting out 12.5v (before switching on lights, wipers and heater etc) and the second, some years later it was shoving out 16v. Both times cheapo nasty alternators were at fault.

Have you thought about a dual water temp / oil pressure gauge?

[DMT]

l rely on my voltmeter for many fault indications.

[Paulfrazer]

It is a bit up in the air at the moment. I thought I was buying the sort of car I could tinker with, fit new instruments, polish etc but it turned out not to be the case partly because of a negligently awarded MOT certificate. Anyway, I have worked my way through many of the faults and when I have recovered financially a bit and got to think of the car as more than a disaster I will decide what to do with the instruments. The dual gauge does look appealing.

[Paulfrazer]

I got a replacement switch but am having great difficulty in getting the old one off. I am finding it difficult to get a spanner anywhere near it but, actually, there doesn't seem to be a hexagon on it. The switch part does seem to have flats on it but I haven't got a socket big enough to fit it and in any case I am wary of using that part to unscrew it in case I snap it off. Has anyone come across that type of switch, with flats on the larger diameter part of it and, generally, is there any technique for getting it off?

I was concerned about an engine oil leak but when I came to change the oil i could almost have unscrewed the drain plug by hand! There doesn't actually seem to be an oil leak now so that is a positive outcome.

[singapore stag]

Would a basin wrench do the trick?

rothenberger-telescopic-plumbing-basin-wrench-7-0225_GPID_1000203562_IMG_00.jpeg

[Paulfrazer]

Ah - I bought one of those a while ago to do a job in the bathroom. In the end we got a new bathroom. I came across it and thought I would never need it so I threw it away a couple of months ago!! I wonder whether it might be a bit bulky but I will go round to B&Q and have a look at them. Thanks for the suggestion

[sujitroy]

a crow foot spanner may help here. On my factory AC Fed '71. It came with a vacuum tank which sits right above that thing. It is bolted to the bulk head. I had to remove the relay plate to get to the bolt heads, remove the tank and then remove the transmitter. You might find it easier to remove the transfer cover, one bolt, and then remove the transmitter. If you do that, I'd replace the Orings on the cover.

[wilf]

Definitely - remove the whole oil transfer cover plate to renew the pressure switch/sender, and put new O rings on it for reassembly - they usually leak from there anyway. Be carfeful when putting the new pressure switch in, it is possible to split the cover plate if you over tighten it.

Use some tiny dabs of tiger seal to hold the O rings in palce on reassembly.