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· International Threat
13,235 Posts
Discussion Starter · #1 · (Edited)
DIY Intake - Options(Open, Boxed, and Dual)

Application 99-03 7.3 Turbo Diesel

Early 99 - 4" section of 4" Exhaust Pipe
Late 99-03 - 3" section of 4" exhaust pipe.

1 open element filter from Napa,Part # FIL6637 or try Part # 46637.
1 Hose Clamp big enough for a 4.5" application.

A few basic tools like a wratchet, extension, sockets, flathead...

Why do this mod?
The early 99 airbox was notorious for allowing dirt particules to pass into the motor and in worst case senario's resulted in "engine dusting". Engine dusting often results in battered Turbo fins (which can be checked by removing the intake tube) and prematurely scored cylinder walls which ultimately results in lost compression and lost power.
The later airbox models were prone to broken clips which would not allow the top of the filter cover to seat correctly and allowed particles to pass into the engine as well.
Performance wise, the tymar triples the filter surface area, thus allowing more "flow" while maintaining acceptable filtration.

First, aquire all needed materials which is in this case the filter, 4" pipe, and a hose clamp. Stainless Steel is what I used, but Aluminized or PVC pipe will also work.

Here is a photo of the materials needed...

Next, you need to disconnect the batteries since you will have to later anyway might as well get it out of the way now and leave them disconnected for at least 1 hour. After that you need to remove the stock airbox. Remove the hose clamp that holds the stock tub onto the filter housing cover.

Now remove the 2 bolts in the back of the filter housing and take the hose off the top of the box and now you are down to the filter.

Remove filter.

Here are 2 pictures showing the dirt that got into the intake tube after removing the filter housing lid. You need to clean this out before installing the filter.


There are 2 bolts in the bottom of the box that need to be removed. After taking them out, twist the white temperature sensor in place and it should pop out. You can zip tie that out of the way, and it will not throw any codes.

You should now have access to the 2 bolts in front of the airbox that will allow you to remove it.

After the airbox is removed you can see the air temperature sensor. This is what you can just zip tie out of the way.

· International Threat
13,235 Posts
Discussion Starter · #2 ·
Next you need to "mock up" the install. Put the filter in the battery tray, push your 4" pipe into the intake tube, and see how it fits. You may need to cut it, like I did but if you do make sure you clean the metal burrs off of it with a wire brush. Here is a before, during and after picture of me removing the metal burrs that you do NOT want in your engine.

After doing this, reinstall the filter like you did in the mockup. Here are a few finished pictures of the install.

NOTE* - Early 99 install will be slightly different, and I will post pictures of that install after Friday when I do one. For now, here is a finished early 99 DIY Tymar filter install.

There are some variations, including a heat shield, and a large clamp or even a bungee cord to hold the filter in place, but I found on my truck that the battery, battery box, hood, fusebox, intake hose, and fender keep mine in place with out any problems.

If you are not comfortable with adjusting the intake hose on the early 99, some say you can use this...

· International Threat
13,235 Posts
Discussion Starter · #3 ·
Here is another writeup from another one of our members...
I wanted to post this especially because of the detailed fabrication of a new airbox.
I've been wanting to put an aftermarket intake on the truck for a while now. Looks simple enough and after reading A LOT of posts and comparing this system and that system, I picked out all the things I liked about different systems and fabricated my own. I'll walk you thru some of the steps and show a fair amount of pictures I took throughout the build and I welcome your input!

Here's the layout at the begining of the build. I spent the previous night drinking beer and making the cardboard template to match the underside of the hood.

After scribing the image from the cardboard to the 22ga aluminum material, it gets cut.

Bending 22ga aluminum isn't the hardest thing in the world but I still used my Hillbilly sheet metal brake. Two c-clamps and a chunk of angle iron!

This next shot you can see the 4" exhaust tubing I used to marry the filter to the stock intake hose. I welded little "ears" on it so I could fasten it to my box (the box is aluminum). Notice the tabs on the side of the box. These tabs rest on the lower half of the stock air box and really help to keep this thing in position when it's installed!

Here it is after paint. You can't go wrong with flat black and stainless steel button head fasteners!

First fit in the truck. Not bad! Please forgive my dirty engine compartment.

Last step. Filter is in and cool AEM sticker is on.

While comparing intake systems, I debated over filters until my head hurt! I really like the idea of a washable air filter and I was dying to try the AEM Dryflow filter. It's reusable and you don't have to oil it. That really blew my mind! It's got a 4" inlet and is 9" long. Cost of materials was $60-65 and time really wasn't a factor. I love hiding in the shop for a day or two.:beer:
Thanks for reading.

· International Threat
13,235 Posts
Discussion Starter · #5 · (Edited)
Info straight off of Fleet Filters website.

Part Number: 46637
UPC Number: 765809466371
Principal Application: Air Filter Assembly for Various Equipment.
All Applications
Style: Air Filter
Service: Air
Media: Paper
Height: 12.380
Outer Diameter: 8.500
Inner Diameter Top: Closed
Inner Diameter Bottom: 4.000
Ends: Metal
CFM: 425

Stock Air filter CFM = 277 for 99-03 7.3
AFE Proguard7 CFM = 582
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