Stop leaking cam plug 1999
 

on the back of the valve cover / head. Do I pull the VC to add RTV to this? Or will removing the plate behind it allow me to R&R it?

Found this:

EDIT: Removed video as it was not helpful.

New or old one with RTV?

I generally pull VC, do that job while i'm there. New one. No reason old one with RTV wouldn't work, but it's not exactly an expensive part.

I replaced my old one, it gets a bit deformed with age. Nothing a bit of RTV won't fix.

If you need to reuse the cap, clean and apply RTV 30 minutes before you put the VC together, and rotate it 90* before installing.
The cap may slip out of position if you don't give the RTV a chance to cure.

I ordered a new plug. I don't remember how the VC interfaces. Would I be foolish to not pull VC to do this job? As in the VC gasket interfaces with the cap that holds the plug in place.

EDIT: Conversely, can I change it by only removing the back-up plate, and not touch the saddle bolts at all?

EDIT2: loosen the saddle bolts. Risk of breaking the RTV glob seals.

Any experience with probability of success if I do not R&R VC? @curly

You can do it without remove the valve cover, yeah. You're just likely to tear the sealing surface as you push it in, and you don't really have an easy way of applying force to install it. If you're tagging me cause I've done ~100 timing belt/water pump jobs at work, the NBs almost never have a leak there like the NA CAS 0-rings.

In a pinch I'd at least loosen those two m8 bolts, barely. If I have the time and I didn't do the valve cover gasket like, yesterday, I'd just remove the valve cover. I also take off the rear cap and front cam caps when sealing a valve cover, to get every last bit of RTV off. Although I haven't done a valve cover gasket only job in a while, the timing belt is usually off, I can't remember if it's advised to remove the front caps with the cam sprockets still on. I don't think it is.

Thanks, Curly. Yes, that is why I tagged you. I'm quite certain that is where my leak is.

OK, I'm gonna do the job right and pull the VC. I have a new VC gasket, so I can change it, too, if the old one is not supple. Really, I don't know why I'm obsessing over a 1 hour job. Probably the $40+ for the VC gasket.

Thanks to all.

I don't have a sample size of 100, but across the NB motors i've had, 3 have leaked there and i've never had a Miata motor with more than 107k miles. I think a lot of people misdiagnose it as a VC leak.

Now that I have VC off, and saddle cap off, I note that the cap to head is a metal-to-metal seal that could allow a path for oil. I plan to put a thin layer of RTV there, in addition to the globs at the corners.

Unneeded, but go for it. So are your front cam caps, are those leaking?

No. No other leaks in system. Good point.

Success. Did pull timing cover and cap. Did not put RTV between cap and head. Did re-use VC gasket, as it was pliable.

Thanks all.