C6 Transmission Filter Compatibility

[Gaugster]

Hi All - Need some support on C6 transmission filter variations between 2WD and 4WD. About a year ago I bought this Mercury and was told it had a “new” transmission.  I think I found a 4WD filter jammed into a 2WD trans/pan? Trans was quirky from day 1. It was overfilled with fluid when I bought it. I figured they knew something I didn't... Now I think it was restricting flow, possible cavitation on a normal (shallow) pan. Took forever to switch from Park to Reverse or Park to Drive. Recently the fluid smelled burnt so I decided to change it.  This seems to be a 4WD filter from a late model C6. 1975-1996. From some quick searches it would seem I have a 2WD version of the C6 as my speedometer cable is connected normally.  Think I read that 4WD versions have the speedometer cable in the transfer case. It's a D servo with an aluminum tail shaft. Pan looks stock. Everything is bolted up but I have not added any fluid. Didn't want to waist any if I have to pull the pan again.

The old filter has some suspicious dents and deformation on the pick-up side. I don't have a picture (yet) but I did notice an outline similar to the shape of the pickup on the bottom of the pan. Almost like a kiss-mark.

The filter I have looks different but bolts up fine. As the whole valve body is submerged in fluid I think this is correct. Need to bounce it off some folks that have seen a few of these though. I took a picture showing the drain plug on the torque converter but the valve body is in the background. Plug was in this position when I pulled the cover so everything was going well until I stared questioning the filter.

[thatdarncat]

Starting in the 1975 model year Ford made the standard C6 passenger car and 2WD pickup pan deeper than the ‘66-‘74 model year C6 pan. That required a slightly deeper filter. The ‘75 & later C6 pan has a distinct corner shape. The filter you have pictured from your car is the ‘75 & later C6 car and 2WD one. I didn’t see a picture of what your C6 pan looks like? If it’s the ‘66-‘74 pan you will have a problem. The C6 4WD filter is similar to the other one you have pictured, but those actually use a filter extension tube that isn’t in the picture, and the filter is deeper too at the end with the hole. In use there is also a rubber grommet that goes in that round hole on the 4WD filter that holds the extension in place, and the matching 4WD pickup C6 pan is even deeper than the ‘75 & later regular C6 pan and has a “sump” shape. I’ll try to add a couple pictures.

[thatdarncat]

Here’s what the C6 4WD pan looks like, with the matching filter and filter extension in place. ( This pan has temp sender fittings added, just FYI. )

[thatdarncat]

Here’s pictures of the ‘75 & later passenger car and 2WD pickup pan. Notice the beveled front corners. This pan is about 2” deep measured from flange to outside bottom of the pan. This is the pan that goes with the filter you have pictured in your pan.

[thatdarncat]

Here’s the ‘66-‘74 C6 pan. It has a taper from front to back, and is about 1 3/4” deep at the front and 1 1 1/4” deep at the back. And a picture of the matching shallow filter.

[thatdarncat]

And just to be complete - there was also an oddball early Lincoln C6 filter. The hole for the fluid to enter is at the edge. Also used for certain model year T-Birds and the 1972 full size 429 Police car. According to the Lincoln Parts Book it used the same early shallow ‘66-‘74 pan.

[HarleyJack17]

"Cat" nailed it. Good info, pics, and explanation. Like the drain plug added to the pan, and guessing a temp port??? I should have done both to mine!

[Gaugster]

Thank you Kevin for the very definitive reply. Here's my pan showing the beveled corners. So I need to go out and get the matching filter. Inside the pan was a magnet but also this odd kiss mark or witness mark that made me question everything. I am using the Moroso reusable pan gasket. Came in real handy today.

[thatdarncat]

Thank you Kevin for the very definitive reply. Here's my pan showing the beveled corners. So I need to go out and get the matching filter. Inside the pan was a magnet but also this odd kiss mark or witness mark that made me question everything. I am using the Moroso reusable pan gasket. Came in real handy today.

By your picture, you have the right pan to match the filter you had. A little hard to see, but it looks like your pan may be bent upwards? Like the bottom has been pushed up? I’d check your pan over very carefully for damage. It may even have been crushed upwards in the past, and then some attempt at straightening it back out, and that’s why your filter also looks like it might have been bent near the inlet hole? I think your observation is correct, that looks like a witness mark of the filter inlet on the bottom of that pan. I know used C6 stuff is getting harder to find, but maybe check around locally at transmission shops and see if anyone has another pan like you have with the beveled front edge? Even if someone doesn’t have one for sale maybe they have one you can use to compare with yours and see if it is damaged? Just like the engine oil pan it doesn’t take much sump damage to eliminate the clearance between the pickup and bottom of the pan, but the transmission pan usually has a broader surface that can be bowed upwards, like if someone tries to jack the transmission up by the pan. Just some thoughts.

[Gaugster]

Thanks for the confirmation and suggestions. As suspected - This pan of mine has some history. Probably as you describe, it was crushed upward and repair attempted.  It was about 1/4" up in the worst spots. Totally obvious with a straight edge but not severe enough to draw major attention to itself. At least not to my eyes. I noticed the scratches on the edges but didn't get alarmed until seeing the insides.

I was able to reclaim that 1/4" and the local auto parts store had the correct filter screen in stock. New pan gasket is also more than twice as thick as original. Should have plenty of clearance now. Also flattened the gasket surface. Took the pan bolts up to 6 ft-lbs. (About half the OEM Spec.) Any more seems to much. Performed the refill procedure per the manual. No leaks thus far. Around 8 to 10 quarts is when I could feel the trans engage gears. Will take it for a gentle drive tomorrow and bring the fluid level to the full mark when completely warmed up.

UPDATE 8/8/20 - The Moroso reusable gasket combine with my old pan was horrible. The old pan is a softer metal and the bolts (no washers) started to pull through and basically ripped the gasket to shreds. Major leaks etc.... Tightening just made it worse. I pulled the pan and used a thin rubber gasket that came with the filter. I flattened the lip of the pan and used Gasgacinch on the pan-to-gasket surface. Transmission to gasket was dry. Was able to add washers to the bolts with the thin gasket. No leaks now thankfully.