Engines don't like ingesting a lot of water. The intake tube on a Tacoma is mounted pretty high (it's inside the passenger side front fender) and when the fender liner is installed, it's pretty well protected from sucking up things it shouldn't. However, there's still potential to swamp an engine. A traditional snorkel with the intake mounted at roof level is nice but is requires a huge hole through the fender and mounting holes through the A-pillar and is expensive for some molded plastic (still cheaper than a new engine though). Also, if I've got water up to the roof line, I probably have bigger problems. I've heard of in-cab snorkels for a long time and a little while ago began researching the pro's and con's as well as seeing what others have done to fit one into a 1st Gen Taco.
My list of Pro's and Con's:
Pro- Hidden, removable without needing new body panels, provides visual of intake level (water needs to be in the cab and above my speakers before I suck water), cleaner intake environment.
Con- Intake noise, intake level lower than traditional snorkel (actually lower than stock intake level but better protected)
Since the fenders were already off for the ditch brackets, it wasn't much of a chore to go ahead and try out an in-cab snorkel. Should I decide against it, I could always patch the 4" hole under the dash and nobody would every know it was once there.
In my reading of other's in-cab snorkel projects, I did not find much info on what setup would actually fit under stock 1st Gen Taco fenders. I saw a writeup on hiding one under 3" extended fiberglass fenders and a few 2nd Gen Tacos but the closest I could find to what I was about to do was a 3rd Gen 4runner. In order to help others wanting to go this route, I'll try to share as much detail as I can here (and also post this in the tech section by itself).
To get some FAQs out of the way: yes it fits under the fenders, yes the fender liner still fits, yes I hear it in the cab.
On to the project-
Step one, remove passenger side fender (already off in my case for the ditch light bracket install).
After some mocking up and some trial and error, I decided I needed to retain the entire stock setup that resides inside the fender in order to clear at the front end where real estate is at a premium. I left the stock horizontal intake tube in place in order to dial in lengths and angles of the tubing.
Next, bore a big freakin' hole through the side of the body into the cab. I built my snorkel out of 3" ABS plastic available at your local big box store. The "ABS to body adapter" I fashioned out of a toilet flange. The toilet flange needed to be cut down on the side that would be inside the cab in order to clear the blower motor and duct work under the dash. The 90º elbow (street fitting- only has a coupler on one side) will attach to the opposite side of what is intended so the lip inside of the toilet flange needed to be removed as well. As luck would have it, the stock intake tube fits PERFECTLY inside 3" ABS. I cut one of the couplers off of a 45º elbow and worked it on to the intake tube. I then test fit a section of pipe between the elbows and marked everything with a silver marker so that I could clock it properly when I went to glue it all together. Once it was call cut, shaved, sanded, and indexed, I glued the 90º elbow into the toilet flange. I then used a heat gun to adjust the flange so that it fit the contour of the body. I also needed to trim about 40% of the flange off on the door hinge side for clearance.
Once I was happy with everything I used ABS cement to glue it all together (just the 3" pipe I was adding, not the ABS to the stock intake tube). Now that I had my snorkel built, it came time to silicone the snot out of everything. I worked from intake side to engine side installing each piece as I went. I did not skimp on the silicone between the body and the toilet flange. It made for messy fingers when bolting it in, but I know it's water tight (I removed the door so that I could get the nuts on the back side by myself). I even siliconed the mating line between the 90º elbow and the toilet flange because I wasn't sure if the ABS cement's integrity was compromised when I heated the flange to form it.
Now that the toilet flange was was sitting exactly where the stock antenna used to reside, I needed to get creative. Again with the heat gun, I formed a piece of PVC then slid the stock antenna mounting rod inside and glued it in place.
Once everything was siliconed together (including the stock intake pieces all the way up to where they meet the air box) and the new antenna mount was in place, it was time to try and get the fender to fit. I knew it should fit because I mocked it up about 15 times throughout the process, but now that it was all actually connected, it was the moment of truth.
AND THE FENDER LINER EVEN WENT BACK IN!!!!! ...but it did take some work to get it in
Now, as for the in cab noise- One person's thread claimed it was so loud they couldn't stand it and removed the system. I can not hear it under normal driving conditions. When I get higher up in the power band or really stand on the throttle, it sounds like I've got a fire breather under the hood. I have made several long road trips and it didn't bother me once. I was bombing down a sandy wash and keeping the R's up in a lower gear so as to keep moving through the silt and it started to get a little droning but still not aggravating. Once I make a trip pulling my cargo trailer loaded down, I'll update the noise report. As of right now, no complaints.