I appear to be missing a nut that keeps my oil dipstick tube in place. I went to check my oil level and damn near crapped myself when the whole tube started to come up as I pulled.

Does anyone happen to know what nut I need here?

Yep the dipstick tube is a push fit into the sump pan so the nut is very important.
There's a couple holding the injector harness on the top side of the cam cover, can you remove one and get a match at the hardware store?

I cannot. Anyone else have anything else more definitive? I'm afraid to take the car for an oil change without this fixed for fear of them pulling the tube right out.

You need the nut, man, period. And change the oil yourself. Sorry to be blunt, but this is a Jag not a Toyota. If you take it to Joe's garage they will pull the dipstick out and probably a whole lot of other things. Good pics though.

Hi Presence,

Since it is highly unlikely that any member of this forum has measured and kept a record of the size of the nut you need, why not visit a hardware store as Sean suggested? If you can't take a similar nut with you to compare sizes, just purchase one each of every metric nut in that size range, say M3, M3.5, M4, M5 and M6, along with matching lock washers.

Our local True Value Hardware has an excellent selection of metric fasteners, and most of the local auto parts stores carry a more limited range of sizes. If you return the fasteners you don't need, you can probably solve your problem for well under $5.00 even if you have to buy packages of 5 nuts and 5 washers in the size you need.

Note that the lock washer doesn't have to be metric, it just needs to fit over the threaded stud and under the nut.

Cheers,

Don

I am pretty sure it is an M5 thread. But, as Don said, most of us would not bother to look it up for ourselves, much less someone else!

edit-
Had another look and it looks more like M6!

He's a nice guy.

Since I will need to be pulling mine out this week anyway, what I will do is pull it off, take it to the store, and measure it to ensure that the thread and size is correct, and I will report back with my findings. I will be able to stop tomorrow evening and report back. I need to get a new bolt for the coil cover anyway.

Yep, we are all sitting in suspense for the nut size!

Wait no longer ................... It is an M5 nut same size as the coil cover bolts and cam covers

If you put a spanner/wrench/socket on the bolt at the side of it on the cam cover housing you will probably find it is 7mm socket, your new nut that you will get from the hardware store will probably be an 8mm socket, because some automotive heads on the bolts/nuts are a mm smaller

That's pretty much the standard diy approach.

Or buy a few of each size that is close and stash them
for future use.

One could also measure the shank with digital calipers
in a pinch(pun intended!).

Your method is sure fire though.

Kick ***. I'll pick up a M5, and a M6 just in case.

Is a Nyloc nut a bad idea? Good idea? Doesn't matter?

Nyloc could be effected by heat, a lock washer is sensible in this application.

Good point, Sean.

According to McMaster-Carr (mcmaster.com), the maximum temp for Nyloc inserts is 250F, so it likely wouldn't hold indefinitely.

A serrated-flange locknut, a nut with integral lock washer, or a standard nut and separate lock washer should work fine. I would not use a deformed- or distorted-thread locknut for risk of snapping off the threaded stud due to the higher torque required to install the nut.

Cheers,

Don

This is why I love an internet forum! !4 posts on a missing nut!

For those who, for similar reasons, may look up this thread in the future:

It was, indeed, a M5 nut!

Funny thing is, it did not even occur to me it would be a metric nut. I am glad I asked and waited for a response before attempting to force on an imperial size.