Oil Pressure sender.

[cass3958]

A bit disconcerting but recently I had a massive drop in oil pressure. From a normal running PSI of around 40 it dropped to below 20 at 3000 rpm and whilst sat at traffic lights it dropped from a normal 20 to zero.

Zero Oil pressure at tick over

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20 psi Oil pressure at 3000 rpm

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Now I checked by looking in the oil cap that I had oil at the top of the engine on tick over so I was not that concerned. I had no oil leaks so it had to be either the gauge, sender or something blocking the pressure relief valve.
Last week I bit the bullet and got under the car and removed the oil filter housing from the side of the engine. Not a difficult job other than access to the five ½ bolts. Once the bolts were out (you have to leave the bottom front bolt in situ as it fouls on the steering box) a screw driver to release the jubilee clip on the bypass hose and the housing slides out. On the bench the housing was checked, the pressure release valve was stripped and cleaned and there was nothing obviously wrong with it.

Oil filter housing. Screw on oil filter modification.

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Oil pressure relief valve stripped

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The housing was refitted (not forgetting to insert the lower front bolt first before offering it up) and everything tightened. Checked the oil pressure and it was still showing no pressure.
OK next was the oil pressure sender. Not a cheap part as they are nearly £90 at SNG which is why I went for the pressure release valve first, but I bit the bullet and ordered a new one. It arrived today and although again it is difficult to get to, an 18mm spanner with one arm down the front of the carbs and the other down the back and I was able to release the old and fit the new. Started up the engine and Hey Presto, oil pressure back up to 20 on tick over and 40 at 3000 rpm.

20 psi Oil pressure at tick over

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40 plus psi Oil pressure at 3000 rpm

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[Orlando St.R]

They are ludicrously unreliable. I must be on about my fourth in 10 years. One I fitted didn't even work properly from the outset. Another one leaked. And, like you say, Rob, this is not a cheap part to buy.

[Glyn Ruck]

Barratts inform me that the latest version is considerably better & more reliable. We shall see.

[cass3958]

I have just managed to pickup a spare off EBay. £30 still in its original box and packing from SNG. Yes I know I have now spent £120 on two but as they are unreliable at least I will have one ready if the one I have just fitted fails in the next couple of years. Now put away in my box of bits I will not sell. Unfortunately when I am gone my wife will either give the spares away with the car when she sells it or throw them away not knowing their value. I possibly have more value in spares than my car is worth but they mean nothing to Maria.

[Glyn Ruck]

Wise buy!! I keep a spare at the tip of Africa. It's like my overblown collection of fog light sealed beams. Not for sale. Many new.

[John Quilter]

If you think they are bad on our XK engines you should hear the complaints with them on XJ40 cars and they are a total PITA to change on those.

[Rogerisleofman]

Must be the time of year for it! Mine did exactly the same thing last month. I bit the bullet on replacing with a capillary gauge and haven't looked back. The only slight problem was that the length of the rigid connector pipe on the gauge end mean't I couldn't close the centre panel quite vertically. Bought an on-line 1/8" BSP elbow fitting and that problem was solved too. And I get an exact reading, not an estimate.

My thinking was better to spend £180 once than repeatedly faff around buying dodgy electrical senders and struggling to fit same.

My tuppence.