Oil Pressure sender (again) -repair possible?

Well, it’s about 6 or 8 years since I swapped out the oil pressure sender last time. Getting the old one off was a huge PIA as I remember so not looking forward to the job but really can’t stand seeing the oil can icon light reviving when I’m sitting at a traffic light.
I’m still reluctant to fit the idiot light so I guess my options are a new sensor/sender or possibly trying to “repair” the one I have fitted at the moment.

In theory, the recurring sensor issue is that the tiny hole in the sender gets plugged with sludge thereby preventing the diaphragm from reacting properly to the pressure. The “repair” idea is to clean out the hole and see if that brings the damn thing back to life.

Thinking carb cleaner bath? Any other suggestions for de-gunkifying the unit?

I realize removing the sensor is awkward so I’m going to make a wrench specifically ground and bent to get the sucker off and back on before I start. Anyone made something up already with a pic or description to share? Oh and I forgot what size the “nut” is on the sender unit … 3/4" ring a bell?

TIA

Larry

Can’t help with the size of the flats but what about a set of crows foot spanners?
And for cleaning how about one of those little portable ultrasonic cleaners?

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The last one I did was 7/16 British Standard across the flats. (18mm is VERY CLOSE)

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Yeah, that sounds good, not a bad call at all - thanks Robin!

Better not wreck a 3/4" one just yet then eh :rofl:

Thinking back, I believe on the 94 the air pump plumbing kinda blocks access. That was the reason we had to go from under the car and also remove the oil cooler bypass to get at it last time …gonna do it from the top this time come hell or high water

Larry …

I agree with you that a direct-read oil pressure transmitter is way-y better than an idiot light … but …
I got so-o-o tired of replacing my OEM transmitters (and you are correct sir they are a PITA to remove) and routinely getting erroneous oil pressure readings that (although purist that I am) years ago I “evolved” over to the idiot light.

While it doesn’t give you a direct reading it will warn you of dangerously low oil pressure. I mean if you puncture your oil pan and all the oil drains out you will get a warning on the idiot light.

So my question is, has ANYONE (or anyone you know of) lost significant oil pressure on this bullet proof Advanced Jaguar 6 cylinder (AJ6) engine ?

Unknown

Yo Larry, a crowsfoot is the way to.go, and yes, removing and reinstalling from the top is pretty much by feel. But if you know what you are feeling for even Stevie Wonder could do it, given enough time…

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I have read, maybe on the old forum long ago, that someone found a GM supplied oil pressure transmitter that would permit the gauge to read varying pressure. At some point Jaguar superseded (1993?) to the Ford type that put the gauge in the middle of the scale all the time if there was any oil pressure. I believe GM pickup trucks and other vehicles had a gauge that read actual pressures. Sorry I do not have any more details but worth investigating if you are having short life from the Jaguar supplied ones.

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From the archives:

Good info about the tool in that link Mike, thanks!

Groove, I’ve got a switch in my spares stash somewhere and if the cleanout doesn’t work, I might have to fit it, we’ll see. The parts car already had the switch even though I dismantled it at 60,000 miles. It was a really late production '94 and may have been like that from factory, I know the X300’s had switches not sensors from day 1.

John, from the part number in the link Mike posted, looks like the aftermarket GM sensor is over double the price of the Jag one even on Rockauto …

Larry, Checking the Rock Auto site I find the GM part number one is $51 and the Standard Motor Products one is $80. The $51 one doesn’t seem outrageous if if works correctly and lasts.

X300 cars from 720001-746613 had pressure transducers and were supposed to be modified.

Subsequent cars were fitted with switches from the factory.

I did this modification A LOT when I worked at the dealer ‘back-in-the-day’!

15-13 Oil Pressure Gauge – Fluctuation.pdf (33.8 KB)
15-33 Oil Pressure Gauge – Modification.pdf (21.2 KB)

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Ah yes, US$ …in Canadian, which is just as hard to come by these days, Standard Motor products one is just a smidge over $100, then there’s shipping …I refuse to shell out that much for a piece of tin, but that’s just me …

And from memory this change from a transducer to switch irritated a lot of customers who bought a car with a gauge and did not want the constant reading that the modification gave. This was probably dictated by Ford engineers as Fords such as the Crown Victoria, had this system. IMHO, it was a cost saving downgrade.

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Hi guys, check this out, do you think this unit would be ok? I can always fit a resistor if the scale is wonky, had to do that with the last one.

The Jaguar classic parts catalog part # is LMD5640AB. Fitment is shown as fairly universal for a wide range of models.

Jaguar Oil pressure transducer (LMD5640AB) part for:
Series iii Saloon 1979 - 1992 Classic,
Xj6 & Xj12 1987 - 1994 Classic,
Xjs Sports Coupe/convertible 1975 - 1996 Classic,
Xj 1995 - 1997 (from 720125 To 812255)

Now the other part, C46272, mentioned above, shows fitment as:

Jaguar Vanden Plas 1982-1992
Jaguar XJ12 1976-1979
Jaguar XJ6 1976-1982, 1987 6 Cylinder 4.2 Liter
Jaguar XJ6 1983-1986
Jaguar XJS 1992 12 Cylinder 5.3 Liter
Jaguar XJS 1976-1991

Hmmmm…

Hmm is right. We have a Daimler, 87 3.6 Have just fitted the C46272… will see how it goes. I was led to believe these were the correct item for early XJ40’s. Dont know if they changed with the dash change or before. Will advise. We had a different problem. Oil pressure was fine at startup but gradually wound off the gauge. May not be the sender but its the easiest place to start. What I tend to do with cars with complex instruments is set them up so they “look” normal but install sperate old school gauges (Oil, amps, temp) under the bonnet (hood) so I can go see if something looks odd. Dont trust new fangled stuff (if you can call 87 new??) cheers

This post from 2007 is interesting re the parts option(s)