Oil pressure sender configuration differences

I bought a new oil pressure sender for my 62 Mk2 from Terry’s. The new one has tapered pipe threads while the installed one has straight threads and a copper washer. Can anyone suggest how I can specify the correct sender?

The correct jaguar part number for the 60 lb oil sender for the MK 2 is C 15474 - what did Terry send you ? All the ones that I sell from the UK have straight threads with washer , although if the tapered thread screws in,you may get away with it by using some thread tape to help seal it !


Thanks for the reply. I’m not at home where I have the records of part numbers. The first one came with no washer and the threads appeared to be tapered threads. I don’t believe there was a flat area at the end of the threads for a washer to seat against. I returned that one and bought the one described in the catalog as OEM. That one did come with the washer and installed properly.
As hoped, it does read a little higher than the old sender. I get a nice 40 psi at around 2500 RPM. But, once the oil gets really hot, it drops down to around 20 psi. A little disappointing, But I don’t think it’s unusual for old jags.

I have exactly the same condition on my 1967 Mark 2 3.4… When driving the car after start up from cold, during the first few minutes of driving I get a reading of 40 psi when revving the engine between 2500 & 3000 RPM. Several minutes later, after engine has reached operating temperature, reading drops to just above 20 psi. Engine runs great, & I’ll guess you ordered your sender part from the same catalog house as I did. My engine is running too well for me to worry about the lower reading.
Mel R.

My 3.8S running 20W 50 oil will almost peg the gauge on first start up with RPM at 2000. On fully warm it runs about 38 lbs at engine speeds over 1500. About 20 at idle.

My 3.4 Mark 2 also runs on Castrol 20W 50 oil. After engine warms up fully, it also runs over 30psi for ‘awhile’, but, on a warm day, especially after encountering several stops at red traffic lights lasting a minute or more, psi will stay close to 20 psi, and only after driving a minute or more at freeway speed, will the psi rise a bit to settle in between 20 & 30. Again, considering how well the engine idles and runs, I’m leaning towards considering the sender and guage as likely culprits. Now that I’m thinking about it (I’ve owned the car 31 years), I remember when I first purchased the car, it came with a 80psi guage which my mechanic surmised may have been ‘lifted’ from a later E type. For years I had wanted to replace it with the correct 60 psi unit. About ten years ago, when visiting a British car ‘parts’ store, I came upon a correct looking 60 psi unit. The vendor, being an honest man, told me though the unit looked the same, it was taken out of a different British marque, possibly an Austin of some sort, and could not guarantee the complete accuracy of the readings. Considering my desire to replace the 80 psi unit in my car, and the ridiculously low price paid for the ‘used’ 60 psi unit, I purchased and installed the 60 psi unit along with a new ‘sender’ unit mentioned in the previous post, so perhaps this might explain the somewhat low readings I’ve encountered since then.

Mel R.

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It’s relatively easy to plumb a mechanical gauge as an auxiliary or a replacement

. I have left the gauges in the dash in two of my cars and mounted a mechanical gauge just under the dash using a copper line kit as have many others. Given the quality and longevity of senders it’s a practical and easy solution.

MRCHB: I think it is critical that the sender match the gauge for an accurate reading. Is there a Smiths number on the face of the gauge? If you can supply that, I might be able to see what it was designed for and what sender went with it. A photo of the gauge might help as well.

After reaching full temperature, my Mk2 3.8L pressure drops down to between 20 and 30 while high speed cruising.

I have tried a variety of oils. The current one is Mobile-1 20W50. It does not seem to make as much difference as might be expected.

The pressure increase certainly does not seem to correlate with the oil’s viscosity rating in a direct way. And the difference in pressure with oil temperature is dramatic.

I am inclined to agree with one of the other commenters; it’s probably fine, don’t worry about it, but it does get me thinking about the cars I have owned in the past that had oil coolers on them.
In a Mk2 the only place you could put an oil cooler would be to cut out the sheet metal behind one of the round false grills on either side of the radiator grill and mount it inside the fender well.
I have always wanted to use one of those for a cool air intake and the other could be an oil cooler.

Ken Wallace, San Diego

I recall from the reproduction competition handbook that came with one Jaguar suggested that if competition was intended the oil pressure should remain at 40psi at 3000rpm - obviously hot. I try and work to this level. The other suggestion that I have encountered is that 10psi for each 1000rpm is about right for cars like ours. FWIW. Paul.

I believe I was the ‘other commenter.’ and I still maintain there is ‘nothing to worry about’ if 20W50 oil, when hot, drops down to between 20 & 30 psi while high speed cruising. I’ve owned the car 31 years at which time I had a complete engine rebuild done. Since then I’ve put 53000 miles on it, and it still runs great. On long distance drives of over 100 miles, with overdrive engaged, I’ve gotten fuel consumption figures as high as 21.5 MPG using the overdrive most of the time. Like I said, no cause for concern.
Mel R.

40psi is the recommended minimum at 2000rpm on a hot engine and all of mine have run at this, but drop well below at idle. I’m not personally aware of a general problem with these gauges reading inaccurately; perhaps a check with a mechanical gauge might be worthwhile. Bought a '97 XK8 a few years ago and was gutted to discover ( via these forums) that the oil pressure gauge ALWAYS reads half scale as soon as the oil light goes out. Seems people panicked about low oil pressure readings at idle so Jaguar ( and others?) relieved people of this concern by having the gauge there as an ornament only.

On my 3.4 Mk2, the oil pressure seemed a little low at 25-30 psi, using 20W50. This on a fully rebuilt engine with about 1500 miles on it.
I checked the pressure relief valve and found that it was not seating properly. Two of the three flutes on the valve were worn so that the face did not seal properly. You could see that the seat was not contacting all the way around.
See pictures below.
I made a tool to reface the seat in the filter housing, using valve grinding compound. The seat is a steel insert in the aluminum housing.
Got a reasonable looking seat bed pattern. A new valve from SNGB has a wider flutes so perhaps they will last longer. The old spring had identical force to the replacement spring, so this was not the cause of the low pressure.
Result was oil pressure of just under 40 psi now. The gauge was checked with a mechanical one and was found to be accurate.
Incidentally when showing 38psi, the needle points vertically down and I think this is the nominal design pressure of theFlute wear 2


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I must say that I used to cheat a bit by Stretching the spring ,which immediately raised the oil pressure

my 67 420 makes 58 psi at idle cold. Warmed up 40. Oil pressure follows rpm. Only running 10w30 oil. 28,000 original miles.