As part of a timing belt job and engine bay refresh, I replaced the majority of the VVT seals with a kit from Miata Roadster which included the cone shaped screen - ZL09-14-3X. This is a 28k mile 2001 car which is bone stock, runs well, no problems before or after. The screen was found loose from the pipe, sitting dislodged in the VVT housing on the valve cover. This appears to be a very common condition from forum postings on miata.net, I saw little about it here with a brief search. Additionally, reports of the screen popping off of the pipe after replacement with a new Mazda part exist. During my replacement, I found it difficult to properly secure the screen into the pipe so I simply placed it back into the VVT housing on the valve cover as before with the assumption it will screen some percentage of oil while I decide what the course of action is. Posts include removing it entirely which I can't say I inherently agree with, as well as the solenoid ports being clogged by broken sections the screen which is likely made easier by the screen becoming dislodged.


Did your VVT screen fit well into the pipe? I assume no one is actually recommending to remove this, correct? Luckily this isn't buried under a cam cap or the cylinder head surface so it's easy to access.

 

Last time I did mine the new one fit snuggly, and the old one came out snuggly as well. An engineer thought a filter was needed there, so I would keep it. If it is loose, I would be afraid of it braking a leg and getting stuck in the VVT solenoid, which I've seen around here before.

 

Remembering way, way back to my VVT swapped NA I believe the filter fit snuggly into the tube as one would expect. Your theory about engineering matches mine as VVT phaser tolerances are quite tight and they are generally non-serviceable by design, thus you sure don't want anything getting into that assembly.

My gut instinct was to pop the tube off and attempt to secure - if I break a plastic tab section off of it attempting this the filters are cheap and the car is parked until spring regardless. My concern was with excessive force attempting to secure the filter into the tube. Perhaps a rougher touch is needed to pop it back in and being my filter was already dislodged I had no reference from removal as to acceptable/expected effort. I wonder what the basis for the Miata.net posts about dislodged filters is? Are they using aftermarket filters, not properly securing them, etc? While traffic seems way down on this forum compared to a decade ago I was surprised to see little discussion here and numerous posts on miata.net. Perhaps the average vehicle on that forum has higher mileage or worse average maintenance? Or maybe just a function of traffic.


Thank you for the data point - hopefully others will chime in.

 

I’m totally the opposite, I’ve had plenty that are loose or a broken tab. Tab Caught by the filter. I figure it acts
like a injector filter and still does a decent job. Obviously new is better, but if you don’t have a new one available, it still works. Typically they’re snug in the pipe when new.

 

Can always cut the tabs and place it inside the lower housing if you are worried they will break at some point.

 

Wanted to update this for those in the future.

I removed the VVT feed pipe mounting bolts to re-inspect this. If one inserts the screen element without it being clipped into the pipe, bolting everything together will bend the element. Since mine was brand new I was able to tweak it back. The plastic is very forgiving so I was able to place the base area in the vise and square it up with my thumbs. It's very tough stuff. Now knowing how robust it is I would not fear pushing on it a bit to have it seat into the pipe. My assumption was it was the more rigid plastic like GM uses for their oil pressure sensor filters but it is flexible.