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I started my '89 XJ6 yesterday and was surprised to see that the oil pressure was all the way to the left; at zero. So I turned the car off afraid that I might damage the engine. I may not know much but I do know that no oil pressure is very bad. Anyway, I have done a little research here and some other sites and people seem to feel that the oil sender that measures the pressure in these engines is a weak point and known to fail. I crossed my fingers that everything was OK even though the gauge said otherwise and started the car. Everything seems OK and I guess the pressure is up where it should be. Obviously, not having this gauge is not the way I want to run the car. I have looked, but I have not been able to find the oil sender on the engine or any info in Haynes where it is located and how to R & R. I was told by a friend that it was forward of the oil filter, but no joy. Any advice would be greatly appreciated for this less than novice Jag owner and tinkerer. Thanks!
It is below and slightly forward of the oil filter. They all fail eventually btw, so you are not alone, almost all of us have had this issue.
You can get a replacement on Rock Auto but it will need a resistor to read correctly on the cabin gauge. Without the resistor it will read way higher than it really is, but at least it won't show Zero any more!!
Some folks fit an idiot switch but personally I like the pressure gauge to show the actual pressure.
here's a reasonably comprehensive thread on the subject
In over 20 years of XJ40 ownership I have never heard of engine failure due to low oil pressure. It's always the oil pressure sender that fails (so far). Here's a photo showing the switch-type sender on our '93 with the intake manifold removed. The transducer-type senders have a much larger body:
And here's another that shows the sender's relationship to the oil filter:
It is far easier to access and change the sender with the intake manifold disconnected and pulled away from the engine, but it can be done "blind" by removing the MAF sensor and air intake elbow and working with a crow's-foot wrench of appropriate size, which I can never remember. It may be one of the standard spark plug sizes (e.g. 5/8 in./16 mm or 13/16 in.). Here are some photos showing how the air intake is disassembled. You only need to remove enough things to access the sender below the intake manifold:
Wow, great photos and advice. I had my fingers on it, but was not sure if it was the sender since I couldn't see what it was. It had a single orange wire coming off it. Now the hard part; remove and replace. I can tell it will be a pain to do it, but I will try. Push comes to shove, I will find a mechanic who can. But, I really appreciate the help here! Thanks!
I think the original sender might be a British Standard size (7/16 BS) but 18mm 'crow-foot' 3/8" drive might work. DO NOT try a 'flare-nut' type tool. It has to be open end to get around the large sender top section.
The square drive might be too close to the open end of the wrench.
I made a tool from a Blue Point 18mm combination wrench in about 15 minutes some 20 years ago for this application. The wrench twisted so I welded a reinforcing piece to the length. The Snap-On dealer was screaming that he would not warranty the wrench because I modified it!!!!!!!!!
You might get an 18mm 'shorty' wrench and smack it with a long bar and hammer to break it loose. Twirl it out by hand??
Does anyone know where I can get a part number. Rock Auto has these senders, one is $5.98 and the others they have are over $40 and look very different than the one in the photos. Is one a OEM and the other not? Do they both work OK? Will the more expensive/larger one not need a resistor? The one in my car looks like the one in the photos above and like the cheaper sender. Just want to make sure I order the correct one.Thanks! http://www.rockauto.com/info/903/1S6678.jpg
The sender in the photo you captured from Rock Auto is of the original transducer type that shows the variations in oil pressure on the gauge. It is preferred by many owners who don't mind the oil pressure gauge needle moving constantly. The smaller switch style is supposed to center the needle on the gauge (with the appropriate resistor in the circuit). In my experience, neither type of sender lasts more than several years.
You can double-check part numbers you find at that site with jaguarmerriamparts.com, which will tell you if there have been any further part number supersessions to be aware of.
If you want the idiot light type, the $5 one is as good as any of the others offered - however, if you want something that registers the varying pressures, spent the $40 plus.
Keep in mind you'll still have to fit a 75 ohm resistor to get it to register somewhat correctly.
Another thing to be aware of is that the reason the sensor has only one wire is that its ground path is through the engine block and engine ground strap. So for a proper electrical connection you want to clean as much oil as you can from the threads in the port before you thread the sensor in. Q-tip swabs / cotton wetted with naptha, brake cleaner etc. will do the trick, but don't quit until the swabs come away reasonably clean.
You also don't want any anti-seize, thread-locker or other substance on the threads of the sensor to resist the flow of current.
05-16-2016, 11:30 AM
Oil sender
