The oil pressure sender keeps blowing after only a few kms travel. Plenty of pressure and oil gauge is fine.
Now on my 3rd one and stumped. Any help please
What brand are you buying, and where is it made?
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Questions arising, Mikeā¦
ā¦,have you actually measured the oil pressure by an external gauge - and what do you mean by the sender āblowingā?
The sender is just a variable resistor - resistance alters with pressure. Two symptoms are evident for malfunctions; a short in the resistor will peak the gauge. A break in the sender will set the gauge to zero - as will a sender clogged by debris. The latter may be discovered by a visual inspection of the sender - which then may be cleanedā¦
You may verify resistance with the engine running, or pressure otherwise applied to the sender. I donāt know the relevant pressure/resistance curve, but it can be assessed by using a āmanualā variable resistor between the wires on the sender and watching relevant gauge readings compared to the resistance appliedā¦
Robās question is of course relevant - though in principle; even the worst quality should not āblowā? And a wrong type should only give wrong readingsā¦
Frank
xj6 85 Sov Europe (UK/NZ)
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And have you looked into the possibility of a bad wire or wire connection point?
Disconnect the wire and touch it to ground. The gauge should peak as Frank said. If it doesnāt, you have a discontinuity somewhere.
I donāt know what the term āblowing outā means?
!. A physical failure with oil spewing all over.
- Or, much less messy, merely failing to cause the guage on the fascia to display values.
Several years ago, I had issues with low numbers on the guage in my Jaguar. But, I did not panic as other facts indicated the OP was just fine. Skipping a bit of the tale, I learned that an after market sensor could be plumbed in and had an option for resistance values. It read the expected numbers just fine.
But, the final fix that is in place today is a NOS sensor sourced vial lister David Boger. It is just fine.
The originals are not known for their robust qualities.
Carl
Mike,
Iām not familiar with the specific 12 cylinder setup, but the XK engine (6 cylinder) uses two sensor - one for the guage, one for the āidiot lightā. My sender for the idiot light had been non-functional for several years. As the guage works I postponed the work until last year. It wasnāt as easy as it might seem, but with the new sender from a usual suspect installed the idiot light works just fine - except maybe that Jaguar idiots must have brilliant eyesight to get adverted from that dim orange light going on ā¦
More or less simultaneously the OP sensor on my Spitfire started leaking - without affecting the operation of the idiot light though. In this case exchange was a breeze and took less than 20 minutes: Again with cheap replacement part from usual supplier.
So, independent of what your sensor has done by āblowingā Iād just put in a new one.
Good luck
Jochen
75 XJ6L 4.2 auto (UK spec)
I have problems with replacement senders for 6 cylinder engine I canāt get originals so have got replacements from SNG Barratt in UK these are made in Australia. Iām about to replace the third one as the present one has gone open circuit. Getting reliable units seems to be a lost cause.
I have just returned from California where I visited XK Unlimited in Paso Robles. I have used them for 25 years for parts and after 3 failed Australian supplied oil senders for my V12 s3 1986 I have brought back a unit they are confident will work. I will fit it when I return home this week and keep you posted on resultsMike
The oil pressure transmitter originally supplied in the S3 XJ12s is the same one in the XJ6s and XJS V12 engines, part number C46272. I was fortunate to pick up a bunch of spare 4.2L XK engines years ago and have been using parts from those engines to keep my Jaguars running, including the oil pressure transmitters. I had a couple of them that started to leak, and another that stopped working, but the spare used ones came in handy and are working fine.
If this new one doesnāt work in the long run, you might try contacting a breaker to see if you can get a used C46272 from an XJ12, XJ6 or XJ-S that does.
Regards,
Paul M. Novak
1990 Series III V12 Vanden Plas
1990 XJ-S Classic Collection convertible
1987 XJ6 Vanden Plas
1984 XJ6 Vanden Plas
1969 E-Type FHC
1957 MK VIII Saloon
Ramona, CA USA
Obviously a ālonger termā test Mike but if it proves reliable then it will be an answer to this problem we have.
I had that issue a few years ago. Time flies. Mine was reading low OP. Ordinarily, that shouldāve alarmed me. But, as my car has hydraulic tappets and they were quiet, I knew I had OP.
But, I got around to a fix. I went shopping for a mechanical guage "kitā. At one time quite popular in the days of domestic cars having āidiotā lights only. No luck. but, I did find a kit using electrics. Sun Pro. Nice kit. I plumbed it in and found the OP was as I suspected. Just fine. The "kitā sensor was bit larger and far more robust, at least in appearance. I learned it had a means of connection in two ways. Differing ohm values! One way read high and the other just right.
I could have left it in place. But, the plumbing was not quite optimum.
Solved. A NOS sensor via David Boger. Great. No leaks and it reads correctly. They are a bit lazy on start up from cold.
Carl
Thanks for the good update Carl. I have tried a mechanical OP which
actually went off the scale and scared me. Maybe too much pressure causing
the blow outs of the last 3 sensors.
STILL getting over jetlag but will take the latest unit to the mechanic
later today. Keep you posted.
T
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Indeed, Mike - verifying oil pressure with an external gauge is highly commendableā¦
What is the peak reading scale of the external gauge? Oil pressure,V12 and xk is very high with cold oil - hence the use of the oil pressure relief valve. Excessive oil pressure is ānot goodā and should be discouraged, though blowing a pressure transmitter would be unusual - and the ;least of worriesā¦
The relief valve is designed to open at around 65 psi - returning oil to the sump āunusedā to reduce pressure. And while there are a variety of reasons for excessive oil pressure; the relief valve should counter all of them. I suggest you check the relief valve operation as a first step - providing of course that your external gauge is reliable, and has a suitable scaleā¦
But high oil pressure is by and large less damaging than noneā¦
Frank
xj6 85 Sopv Europe (UK/NZ)
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A couple of decades ago, or more, my son still lived here. His
project, getting more power from his already quite warm Tbird engine in his classic 1940 Ford coupe. A remote oil filter!!!
And a mistaken belief at the time, that it needed more OP.
Got it! Blew the canister 'clean off"!!! Ugh, too much. What a mess that made!!!
Just a lesson on a path to becoming a master at high performance engines. Flow is far more important than PSIās.
GM engineers are not dumb, nor are most others. My lump does just fine at 40 PSI maximum. Itās designed that way.
Carl
Thanks for the info Frank Iām hoping to fit the new sensor purchased in USA last week shortly and will advise results.
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But still, Mike - what was the pressure you were readingā¦?
Apart from the relief valve, and possibly a faulty reading; oil pressure will rise if oil channels are clogged. Single point clogging will not be noticeable on pressure, but will still be damaging of course - but a clogged oil filter will read low/nil oil pressure. excessive oil pressure should still be pursued thoughā¦
FRank
xj6 85 Sov Europe (UK/NZ)
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Hi Frank. Pressure was almost off the dial. In fact a bit unnerving.but it dispelled the fear of an oil blockage. We had to make a special tool to remove the original sender and this along with my mechanical PG are in his shop. On my return from USA with a new replacement I found he was on holidays until end of July. More to come.Mike
I am surprised that a special tool is required to remove and replace the engine oil pressure transmitter. Attached is a recent picture of the 5.3L V12 engine bay in my wifeās 1990 XJ-S convertible (same basic engine as in my 1990 V12 VdP (a Series III XJ12)) showing the engine oil pressure transmitter. I admit that it is a little challenging to get at without some disassembly. But why was a āspecial toolā required?
Regards,
Paul M. Novak
1990 Series III V12 Vanden Plas
1990 XJ-S Classic Collection convertible
1987 XJ6 Vanden Plas
1984 XJ6 Vanden Plas
1969 E-Type FHC
1957 MK VIII Saloon
Ramona, CA USA
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But still, Mike - what was the actual pressure reading on that gauge scaleā¦?
Frank
xj6 85 Sov Europe (UK/NZ)
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Paul:
Interesting.
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It does not resemble the sensor in my car. Smaller and flatter, no apparent dome. Mine is the one included. with the 4.2 DOHC.
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It does resemble the one that came with the after market OP accessory Sun Pro unit.
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I understand the mechanic choosing a special tool over taking things apart. It is an inbred thing. Production. and less chance of messing up other stuff.
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It does seem that a "crows foot wrench would do the job.
Mike:
- donāt that beat all. Gone til the end of July and you are left in limbo??? No prior advice of that ādead timeā.
Another example of āserviceā or more like the lack thereof.
My daughterās āexperiencedā Apple lap top has out dated itself
in respect itās operating system and memory capacity. It canāt handle a special program for graphic artist. She bought that decades ago. Up dating it another āstoryā.
She found an independent shop in anearby town that purported handle the issue for far less than the āBig Appleā store. Ugh, closed. Answer message not updated, merely asks for a messageā¦
The Service thing strikes again.
Carl