How To Install An External Transmission Filter Kit
This tech article was originally posted at FordF150.net. It is primarily intended for Ford trucks but most likely also applies to other Ford models.
As per maintenance I decided as the transmission was starting to show its age, I would install an aftermarket external (remote) transmission filter. From reading on various forums it seemed like a great idea. With added cooling and added fluid, what is there to lose?
If you can change your transmission fluid and do basic automotive electrical work, then this install is quite simple. The hardest part is the planning stage, so take your time, do it once, do it right.
This is for a 1998 Ford F-150 4.2 V6 2 wheel drive with a 4R70W automatic transmission and the towing package, however it would apply to all 4R70W equipped F-150’s (2WD or 4WD), from 1997-2003 and the process would be very similar for 2004-2013 trucks as well.
So, why install an external transmission filter?
- Cleaner fluid, lower fluid temperature
- The ability to cut open the filter for inspections
- 2+ quarts more fluid capacity
- The ability to change roughly 12% of the fluid with each filter change
- Perma-Cool 10677 with trans temperature gauge or 10678 without, or equivalent remote filter kit
- Motorcraft FL1a filter or equivalent (I wasn't entirely pleased with the filtration specs of the filter that came with the Perma-Cool kit)
- Transmission line adaptor fittings Hayden 395 or Hayden 384 depending on your application 90 degree elbows makes line routing easier
- Hose clamps - some come with kit but as you see in the pictures I did marine style clamping with 2 clamps on each hose
- Zip ties
- Screw in wire holders
- 3 quarts transmission fluid. Always helps to have extra fluid! Be sure to check the specifications! The 4R70W transmission takes Mercon V fluid
- Teflon tape for the threads of the fittings
- Self tapping screws
- Additional transmission temperature gauge because in my opinion the one that came in the kit had too broad of a range
- Goodyear E-Z Coil to bend the hose into shape
- Extra hose to prevent newly located hard cooler lines from rubbing against one another
- Solder seal terminals or heat shrink and solder crimp butt connectors for hooking up gauge (will be included with kit)
- Extra wire
- 1/4" socket set
- Drill bits and drill
- Wire cutters, crimpers
- Various wrenches
First, open all your boxes up and make a plan on where your going to install the filter, the gauge, etc.
Next, find the transmission outlet and inlet cooler lines coming from the transmission. You can find the outlet line when the truck is warmed up by feel, the outlet will be hotter. Some say use the return line as the temperature will be proof that the coolers are doing their job. I wanted to see the hot side temperature. Make sure you have the filter installed the correct way!
Transmission Filter / Gauge Setup Diagram
Install your adaptor fittings using Teflon tape and run your lines. Secure the lines using zip ties, your ladies bra, dogs leash, the screw in wire keepers, whatever. I chose to run them along the length of the radiator shroud.
Install the sending unit for the temp gauge into the housing if you got the appropriate kit. Make sure your fittings are tight and have Teflon tape on them... they will leak! next wire up the gauge according to the instructions included.
Be sure the sending unit is grounded by running a wire from the filter mount to the firewall as you see in the picture below:
I did not use Teflon tape on the sending unit at first until I discovered a leak. It is ok to use the tape on the sender because the threads on it will cut through the tape and make a good ground contact.
Crawl under the vehicle and as you will notice the transmission cooler lines have moved do to the addition of the adaptors and now in some places they rub together. Install hose around these lines and zip tie them in place. Granted this may not be a problem...but better safe then sorry.
Fill the filter up with fluid and install the filter on the mount. Start the vehicle up and check for leaks. Top off the fluid as needed. Enjoy your new external transmission filter! I change the filter along with the oil change. each filter change gives me about 12% clean fluid back into the transmission.
Overall it took about three hours to install the kit. This article and associated photos were written and contributed by thefordmaniac, and is used with permission.