O Ring question
 

I am thinking about replacing the assorted o rings that form air seals around the engine....like the dipstick etc. The local auto supply has a large kit of assorted o rings for $14cdn, but the diameters are all imperial measurements expressed in 32nds of an inch ! ( god knows why , because we changed to SI measures in 1978 )

Have any of you American folks used imperial measure o rings and can you tell me if they fit OK. I can probably get metric ones on e-bay but it's so much easier to just go to the store

I have yet to replace any leaky o-rings on my 2004 with now 97K miles. Granted I am in a climate that favors rubber bits with longevity.

I am all about preventative maintenance, but this seems like a solution in need of a problem.

I would not risk the R&R of related parts just to get to an o-ring that was not leaking. Enough aged plastic shit already breaks on this car when touched. :icon_twocents:

Wouldn’t replace the Oil Dipstick O Ring unless it’s leaking
 

+1 to Rothwell

I’m all for preventative maintenance but search for threads on dipsticks, and it’s a major PITA to re-install. For this one O Ring, “If it ain’t broke, don’t fix it.”

Using standard mm Auto store mm O Rings, I’ve replaced only a few in the engine bay which was the PCV full load breather cam shaft cover connection, and the octopus hose. No problem so far.

Someone on this forum suggested using modern silicon O Rings as they should be more durable. Not sure imperial dims will give any better results. Maybe you just need a bigger box for selection. Cheap stuff!

Good point on the dipstick and probably a bad example on my part. I have noticed that the O rings on the breather pipes are looking a bit rough and was more interested in replacing those.

I am the dissenting voice on this. I think it is a great idea to get ahead of those small air leaks, one at a time. These Norma connectors are easy to remove to expose the o-rings. Take your time and go around the heads and throttle body. Best is to keep an eye on the fuel trims and hopefully watch them go down as you plug up these leaks. Do the o-ring on the dip stick itself. Also, do the VVT seals if you see oil. Last, check the hard plastic line to the brake booster. That funky brass/plastic fitting has an o-ring involved too. Don't forget the o-ring at the base of the air flow meter. Obviously, best would be to do a smoke test to find actual leaks. There are so many seals/gaskets, it becomes depressing to identify them all...

Best of luck, keep us posted.

Thanks for all the good advice. Can anybody answer the question about imperial vs metric O-rings sizes though ?

I've got at least four different O-ring assortments of both metric and merican sizes and different materials and found a mix on the X308. 200-300 piece assortments are $8 to $12 on Amazon and its good to have o-rings on hand. But I've also run into a couple that I couldn't find in my various assortments and had to order individually or as package of 10 or whatever. If you are replacing other Jaguar parts anyway, then you might as well add the correct o-rings to your order and save you the trouble. But I like to keep the assortments handy because often I have to take something loose to get to something else, didn't plan on replacing that particular o-ring, so didn't order it and don't want to wait another week or pay shipping on just one o-ring.