Inner shift boot damage. Heat, Age, or Tans fluid?
 

Hello,
I am slowly working my way through the long list of items that need attention.
Today I pulled the shift boot out of my 1991 f250 with a ZF S5-42 transmission. The plastic trim ring holding it to the floor is broken, all 4 of the screw points have separated from the trim. This left 4 screws and 4 bits of plastic on my floor and the boot was free floating. I had been noticing excessive noise and heat in that area prior to investigating a few months ago. Just now getting around to dealing with it.
I also noted that the boot on the top of the trans is cracked and there is fluid on/around it. I located this replacement part so likely not a big deal.
more concerning is that i noticed that the inner cab boot, what I see referred to as the insulator sometimes, is badly cracked and the forward 2 corners as well as a portion of the part that the stick passes through are no longer soft rubber but act more like hard brittle rubber.
Before I go spending money on new parts I wanted to ask for your thoughts.
I do have some exhaust leakage, my manifold gaskets are failing (plenty of ticking, no roaring). I get more heat at the back of the engine bay than is ideal but I have seen no evidence of this causing any harm yet.
Is the damage to the boot and possibly the plastic trim caused by heat, the leaking trans fluid from below, or just old rubber?
I did have a mechanic put new input, and output seals in the trans for me about a year ago when I had it out for a new clutch.
The outer cab boot is in pristine condition so I will re-use it if I can find the other 2 parts (or just the insulator if I can glue the trim)

I will see about getting some images in here for your viewing pleasure.https://cimg2.ibsrv.net/gimg/www.f15...a2ee34fd92.jpg

Bottom of outer cab boot. all 4 screw points broken on trim ring.
https://cimg7.ibsrv.net/gimg/www.f15...fd21987f71.jpg

All of the plastic pieces that I could find. Glue?
https://cimg9.ibsrv.net/gimg/www.f15...342047f660.jpg

Top view of inner, insulator, cab boot. image is not skewed. right hand (forward in truck) area is shrunk, hard, and brittle.
https://cimg1.ibsrv.net/gimg/www.f15...44fa06db17.jpg

Side view of inner cab boot.

Moved to Super Duty.

Sorry about posting my inquiry in the wrong section.

I have some additional info this morning that may help. Last night I completely cleaned the inner boot. When I set it down on the towel it was dry and free of dirt and oil. This morning, all of the areas that are hard are also sweating what I assume is transmission fluid. Not a lot of fluid but the surface is wet.

In addition, I let the truck run long enough to warm up and then stuck my hand down through the open shifter hole towards the front of the truck. There was no heat that I could feel there leading me to believe that the exhaust leak, while concerning, is not causing heating in that area.

For now, I will assume that the damage was caused by the transmission fluid breaking down the rubber over time. I will replace the small transmission boot that is ripped and keep an eye on it. If I see any more fluid show up I will do gaskets as well.

I believe that I can save my damaged trim ring. I have some good ABS glue that seems to adhere quite well. So far the only place that I have found to buy the inner insulator boot is part of an assembly that includes the trim ring and the outer boot for $65-$70. If anyone has a line on the inner boots alone I would appreciate it.

'91 is getting old at this point. I've replaced nearly everything rubber on mine due to dry rot. I think you're right about the fluid causing the failure too. The fluid is probably petrol based which would destroy those rubber components over time.