With confidence buoyed by the fading of memories of past failures I have embarked on the next great challenge, accurate oil pressure indication. Now I know that the consensus of the enlightened is to ditch the electric gauge in favour of a mechanical one, to the extent that SNGB now stock them as upgrades, but where is the challenge in that? This of course is the gauge in question, OEM Jaguar part number C33118:
Connected a variable resistance and measured the calibration, ohms versus indicated psi, the blue line in the graph below. Was a bit disconcerted by the nonlinearity, till I found this topic where Phil has measured similar (= orange line), so I guess that’s how it is.
Jaguar part number of the sender for this gauge is C31177. According to Smiths Instruments UK website ( https://www.smiths-instruments.co.uk/pr ... ransducers
) this is a PTR1811-10, which is what SNGB send when you buy a C31177.
Trouble is it never worked properly, was almost all the time pinned off the end of the scale except, when steaming hot and idling, it might drop down as far as 60 psi. And now it has died.
Smiths agent in Aus is Howard Instruments. Howard is a nice bloke, I send him pic’s of my gauge and my characterization data and he sends me pic’s of his test bench showing his recommended sender, PTR1001-10EC, making an old Smiths gauge read close to 100 psi correctly.
Until my persistence that this might not actually be proof of anything became irritating, then all he would send me was an invoice.
PTR1001-10EC sender duly arrived, hooked it up to the air compressor and measured its characteristic, the yellow line on the graph below. To read this graph, example as per the red arrows: Oil pressure, when it is 47ish psi, will cause the sender (yellow line) to have resistance of 180 ohms which will cause my oil gauge (blue line) to indicate about 13 psi. Not so good.
MLBS3V12 wrote: ↑
Thu Feb 20, 2020 5:57 pm
Hi all, I've a question on the oil pressure sensor. I do use the one from the XJS V12 engine on my E Type. At idle pressure read on the gauge is close from 20 lbs only. I suspect that the sender must be changed for an E Type one. Thank you for your remarks.
Michel, I’ve never had an e-type oil pressure gauge that worked correctly. But from what I’ve read, 20 psig when warm at idle is what it should be, can anyone confirm this?
And Michel, please can you advise, what is the part number of your oil pressure sender?