I'm finding the mantra "While i'm there, I might as well do that" really doesn't work well on a Jag V12!

My pressure sensor was leaking a bit so I thought i'd change it, but for the life of me I can't undo it. Has anyone done it recently & can confirm exactly how tight it should be? I'm really worried i'm going to break the little aluminium part it mounts on. I have the throttle pedestal removed so can fit in a regular 18mm wrench.

Also, I noticed the one in the car appears to have a copper crush gasket as a seal, but the replacement i've received has a tapered thread. Again can anyone confirm if they are interchangeable? I guess if the thread pitch is the same the tapered thread could still work. The p/n of the replacement I have is c46272.

 

TIGHT usually.

Any I find like that, I remove that central Banjo fitting, the 2 small bolts, and up on the bench where disasters are less likely to happen.

DO NOT touch the banjo bolts at the rear of the head area, coz if you screw that up, its engine out to rectify.

NEW copper washers on refit please.

Tapered thread is WRONG. The large sender, for the gauge is straight thread with a copper or ally washer. The smaller sender, for the idiot light, is tapered. 1/8BSP on mine.

 

This is a job I need to do... so keep us informed... OH and we like pictures!

 

Managed to get it off in situ - Used an adjustable wrench to hold the base/pedestal part from twisting, held that in place with my left hand, & got it off. This would be much harder if you still have the intake manifolds in place - crows foot wrench would make it much easier.

So, regarding the tapered issue. Here's a pic of the new sensor:



I've had a chat with the suppliers - apparently they are all supplied like this now (changed design) & they can't get a parallel thread. I've also had a second look at the one in the car & it looks like it might also be tapered, but hard to tell - could just be a bit mashed up. It's definitely very bad practice to use a crush washer with a tapered thread.

I think it will fit OK, with some PTFE tape on the threads just in case.

 

Well done, yes, the LH words of encouragement always work.

Probably OK with that sender. I have always managed to get the OE spec one when I needed one, bit it has been a few years now.

Check the ohms prior to installing, as the Jag uses a reverse ohm set for some bizzare reason. You are looking at about 650ish ohms at rest, and then as pressure is applied it goes to zero-ish, the exact reverse of a "normal" gauge sender unit.