I'm doing the tranny cooler install on my 3rd gens and I'm not happy running my ATF cooler lines through the A/C firewall hole without shielding them in some way from the metal edges of the hole. I considered running the lines through a section of vaccum hose to act as a channel through the firewall hole, but that got bulky and put a little pressure against the A/C lines.

I finally decided to slit a length of 1/8" (or 3/16", I forget) rubber hose and used it to line the perimeter of the firewall hole, essentially making a grommet for the hole. A test fit allowed the ATF lines to pass through with a little more wiggle room, so that's good. The grommet is fairly snug, holding itself in place with friction, but I'm concerned that it might vibrate loose during operation.

My question is: what can I use to 'glue' or otherwise adhere the grommet in place, so it won't come loose later? I was thinking about using some RTV and trying to squeeze some into the tubing, gluing it to the metal firewall. Any better ideas?

Thunderstorm interrupted work, so no pics until later.

 

Superglue ? Epoxy ? RTV ?
A mixture of all three ?

 

Well, I've considered all three. I was hoping someone would mention something that has worked for them (or advise me of what didn't work).

 

Why are you routing through the firewall? I just connect the lines close to the radiator and run the cooler somewhere behind the grill?

 

Here's my cooler setup. I'm running the lines behind the A/C receiver, through the firewall where the A/C lines pass through, because it's a simple route. I just want to get that grommet stuck in there good so I can proceed with the install.

 

RTV silicone no doubt.

Are you wanting to make a new hole a couple of inches below where the A/C lines pass through, insert a grommet there, and then run your cooler lines through it? You can get all sized rubber grommets from most local electrical shops for less than $5. Just make sure to debur the metal hole after drilling it and run a little RTV inside the grommet's lip before installing the grommet.

Take some pics. I saw a guy once on his F150 do the same thing for an external tranny cooler. Make sure to have a good drill and a step bit at your disposal.

 

wrap it with tape and use RTV..

 

I considered drilling, but the location is sort of hard to get to. Besides, the existing hole for the A/C lines is perfectly sized and placed for this application.


Here's a pic of what I ended up doing. I split the 3/16" rubber hose (red arrow) and glued it in place using blue RTV (visible along the top edge of the grommet). The grommet is fairly secure without the RTV, but I think the added adhesion will be good. I cut the hose for the grommet a little short, but the width of the cooler hose that will be passing through is enough that it won't be able to touch the metal edge. Yellow arrow points to the A/C receiver so you have an idea where you're looking.

 

Looks good. If you are sure the line won't touch the metal, hook it up,add some ATF, run it, and take some pics..........

 

Wrap the lines with a piece of radiator hose and zip tie it.