Howdy Folks!!...
Checked my oil yesterday, and was about 3/4 quart low. I had about that amount left over from my last (shop) oil change, and figured I would top her off. Well... (just turned off the engine about 5 minutes before) I tried to twist off the cap and it wouldn't turn. It would tighten and click, but wouldn't turn counter-clockwise. I mean WTF!!..... Then this morning I waltzed out there and "Presto"... it turned right off. What in th' Wide World o' Sports is up with that?? Do I need to order another cap?? or is this some Jaguar quirk...

Drive On!!...

Fast Freddie

 

Alas, more plastic failures. The ratchet assembly in the majority of oil caps today are plastic, just like the cap itself. Over time and heat cycles, the gearing inside breaks down and wears out, and oftentimes the caps just spin as you described. When yours cooled off, the ratchets apparently functioned properly again, but I wouldn't wait for the next failure. I'd go ahead and replace it. And not necessarily with an overpriced dealer cap. You can find generic caps at NAPA and other parts stores....

I've had to replace the oil caps in several different vehicles over the decades for reasons exactly like you described. My 1999 Dodge Ram pickup sports a generic cap, as did the majority of our Jeep Grand Cherokees if we kept them long enough. I remember having to pull several failed caps off with a pair of channel-lock pliers once I finally got them spinning properly again, always after the engine cooled off and the plastic parts had time enough to contract....

 

I did change my dad's ride's cap to a chrome one too . However, main part in which the cap is driven is also plastic so in our case it's a wise idea to not tighten it all the way down lol

 

I interpret that to mean it would not turn at all, not to mean that it spun freely. Maybe some clarification would help??

 

{I tried to twist off the cap and it wouldn't turn. It would tighten and click, but wouldn't turn counter-clockwise.}

As I had mentioned, it would not turn (or rotate) "lefty-loosy". You could rotate it clockwise, and it would turn and "click" each full rotation. I had her out for a little spin yesterday, and when I got home I tried to take the cap off...same thing. But this morning (engine cold) she turned right off. So go figure. At any rate, I just ordered a new one from LVJP. If nothing else, it will give peace of mind.
As an aside, I was perusing the manual to see if I needed do a little dance, or perhaps a Lodge Brother hand shake to get the cap off when I turned to page (I think) 196-197. On these pages it shows the various locations for filler caps. and lo and behold, it shows figure 2 as the oil filler cap, and 1 as the brake fluid cap. When in reality... they are in reverse order. I wonder how many newbies had to flush their brake fluid system after following the books instructions.

Drive On!!...
Fast Freddie

 

I've seen it wrong for the V8 at one place (you wonder how!!) in the 2004 handbook (it's right just a few pages on where it tells you how to top up), despite being right in earlier and later handbooks. The one for your car year looks to be right so I guess you have an old one?

 

I can't say that I've ever tried to loosen my 710 cap when the engine is hot, so maybe your observation is 'normal'. Maybe try it again?

Extra bowl of Wheaties in the morning?

 

Ive noticed the same in my R, the 710 cap has issues cracking open, I think its due to the crankcase pressure, because if I leave it alone and come back hours later it twists off fairly easy. can anyone else confirm this about the 710 cap?

 

Well if the 710 filler cap won't come off, you are 705

 

I had an issue today doing my first oil change for the STR with the oil cap being stuck. Just a tip, try tapping lightly on the oil cap with a small hammer or the end of a wrench while loosening the cap. I don't know why anyone would have put the cap on so tight. It had a jaguar filter on it so it was probably a dealership who did the last change. I do think the car went many miles without an oil change so the cap may have been tightened through heat cycles. Tapping on the cap worked for me.

 

The OE cap seems to me to have an integral mechanism (*) which prevents overtightening.

(*) some sort of release ratchet - I'm sure it'll have a name but I don't know it!

 

Howdy Folks!!...
I received my new one today... I noticed that my new cap had what resembles an "O" Ring at the base. My old one was collapsed at that point. Who knows... I'm takin' her for a little spin tomorrow, I'll see if the cap comes off when the engine is up to temp.

Drive On!!...

Fast Freddie

 

I think it is not the cap but the filler tube. The grooves in the filler tube end and the cap slips back to previous ones if too tight. There are no moving parts involved and the cap is one solid piece with an rubber o-ring for seal. At least in my car, that is.

But yes, I have had hard time opening mine, but it is just matter of twisting harder.

 

No, there is a clip at the base that needs to be lifted with a pick.



2006 XJL x350 4.2

 

I find that when my car is cold the cap comes off easier...why I have no idea..I have used channel locks to get the first twist before..it is kind of hard for me to get a good grip also because of the location

 

 

That pic's not the same as my car.

 

I have a 2006 XJ8 4.2 X350 lol you dont have the same one? Ohhh Jaguar... smh