Mantec Snorkel and Custom Plenum Install
Problem: Previous owner had fitted a hard molded plastic “Safari” snorkel that was no longer compatible with the A-pillar leg of the recently installed external roll cage.
Solution: A Mantec snorkel with flexible tube where the vertical breather tube can be fixed/mounted to the cage’s A-pillar leg.
Yeah, it sounds simple doesn’t it? That’s what I thought. Or at least it could have been simple if the wing hadn’t already been cut for the safari snorkel and the new position of the Mantec opening wasn’t 3” forward so that the internal plenum connection to the breather hose wasn’t too close to the wheel well.
Sure I could have used the internal plenum that came with the Mantec snorkel by butchering the wheel well to accept the bend without kinking the hose and restricting airflow.
So really there were two major hurdles to pull this off correctly.
First, something would have to be done to deal with the gaping hole left by the previous snorkel. New hole/cutout was smaller and needed to be forward about 3" to clear the cage leg. New wing wasn’t out of the question, but I decided instead to fabricate a patch. Actually, it sounds much better and purposeful if we call it a wing “guard” or support instead of a patch. As it turns out this was the simple part. The first guard was made out of medium gauge sheet metal. I then decided that no matter what I did it would rust and bleed down the fender, so that was scrapped in favor of leftover birmabright from discarded van sides. (before you cry sacrilege, the majority of the van sides went to a board member for a custom 100” project truck and only the leftover material was used). I also decided that trying to match the Epsom green paint would be a waste of time. It would never look right and would look like a mistake. Instead, matte black may look like it was part of the Mantec package to stiffen the wing etc.
Second, and most difficult was how to address the awkward angle and position of the inlet meant to receive the hose coming from the filter housing. Instead of butchering the Mantec plenum, I fabricated one from fiberglass. The tricky part was creating a mold that could easily be removed from inside after the fiberglass had set. Thought about plaster/papermache , but at the last minute was driving by a florist shop and the idea struck me to use florist foam which could easily be shaped and also would disintegrate easily when the fiberglass resin had cured. 4x8x8” block was used and shaped into a plenum large enough to accept the bolt pattern of the exterior tube as well as a 2” PVC fitting to attach to the hose going to the filter. Having limited experience fabricating with fiberglass, it was a messy challenge and ended up being over-engineered and strong enough to stand on (to hide all the irregularities, I ended up doing like 5 applications and it is now Ľ” thick).
Anyway, it is ridiculously stout. When molding the foam, I had inserted medium-gauge steel along the rim that mates to the fender and receives the outer portion of the snorkel. That way the screws will have something of substance to grab on to along with clip-type “U nuts” . In hindsight, threaded nutserts embedded into the resin would have been better, but the Mantec plenum used “U-nuts” so I thought that was okay. The florist foam worked great, when the first application of fiberglass/resin had fully cured it took about 5 minutes with a spoon to scoop out all of the foam. As I said, this plenum ended up being overbuilt and you could probably use it as a wheel chock if all else failed. I did spray the inside of the plenum with rubberized undercoating just in case there were any stray air pockets or voids that were missed.
Now that the two parts were fabricated it was time to tackle the installation. Normally, this would be a Sunday afternoon job when the sun was shining and time would be measured in 6-packs, not hours. However, I was so anxious to get this together after spending way too much time agonizing over how to fabricate the plenum and then taking too many hours to build it, this had to be done as soon as light and temperature would allow. I have the same problem as many of us D-owners in that my garage opening is about 6” below the overall height, so it’s like a sick joke that I’ve got a nice warm garage but can’t work on the Defender in there. Anyway, I digress.
After dry-fitting the “guard” several times and pre-drilling all the rivet holes etc, I used 2-part body panel epoxy/seam sealer to create a bond between the wing and the guard thinking that the minute water got between the two panels it was the end. Fast forward through the hour of fighting with those retarded “u-bolts” (two of which cracked and became useless), I epoxy’d nuts on the inside for those two and used machine screws instead of #12 stainless sheetmetal screws.
Here is the result after black epoxy was carefully applied to the seam between the “guard” and wing. I thought this worked out pretty well considering I was looking at getting a new fender altogether. I’ll admit that I may never need a raised air intake for the kind off-roading and daily driving I do, but remember something had to cover that hole left by the Safari Snorkel.