Installing a Transmission Pan in a 1969 Chevelle
My ’69 Chevelle build is going a little slower than I would like, but what else is new? Some things shouldn’t be rushed. If you haven’t seen my last couple posts about the project, check out Installing a Differential Cover and Preventing Paint Damage.
I’m swapping out the original turbo 350 automatic for a built 700R4 4-speed automatic. I found myself a sweetheart of a deal on Craigslist (where else?), but just to make sure the deal was really a deal, I pulled the pan and filter to have a look-see. Before I go into how I reinstalled the pan, I thought I would show what happened when I removed the old filter.
Condition of the pan and filter
You can see in the pictures here below that the seal on the input tube stayed stuck in the transmission when I removed the old filter. I was able pick it out with a dental pick and a screwdriver before installing the new filter, but watch out for these types of issues when changing filters. I’ve seen things like this lead to big problems when they are not caught. Before installing the new filter, I coated the new seal with clean tranny fluid.
Here’s the old filter seal stuck in transmission:
And the filter inlet cleaned out and ready for a new filter:
And finally the new filter with a correctly seated seal, coated with clean tranny fluid:
Cleaning before sealing
As usual, you see here I’m using Loctite® Pro Strength Parts Cleaner. Any cleaner that dries residue-free (brake part cleaner, carb cleaner, isopropyl alcohol, acetone) will suffice. I like to apply the cleaner to a clean rag or paper towel and wipe the flanges several times over, moving to a clean spot on the towel until I stop seeing dirt/scum buildup on the towel. As with any sealing application, clean and dry helps ensure a good seal. I masked and painted my tranny with the pan off, so I was sure to wipe well and make sure that I removed any overspray.
Below is my trusty Pro Strength Parts Cleaner for cleaning flanges, pan, and fasteners:
Time to seal
Loctite® 598™ Black Silicone is my product of choice, as it has excellent oil cutting and resistance properties and will give me a consistent clean look after assembly is complete. I eliminated the original cut gasket because over time, they have a tendency to dry out, shrink, or crack, leading to leaks.
Additionally, on tranny pans I’ve had bolt holes squeeze open (expand), leading to leaks later on. The flange on this tranny is flat and smooth, so I applied through a 1/8” to 3/16” opening in the nozzle, being sure to circle the bolt holes. On the 700R4, many of the bolts are through holes but some are not, so I circled them all to ensure no leak paths.
Here’s what the 598™ Silicone looks like after it’s applied:
Attaching the pan
Next, and finally, the pan. I carefully set the pan in place, lining up the bolt holes in the pan with the threaded holes in the transmission. I applied LOCTITE® 243™ Blue Threadlocker to the bolts that secure the cover. For the bolts on the through holes, I applied a drop of 243™ to the bolt. On the blind holes, I applied a drop of 243™ on the bolt and in the hole.
Here’s 243™ on the pan bolts:
I tightened the bolts in a cross pattern all to snug at first, then to the proper spec as required — for my job, 80 in.-lbs. first time around, then 120 in.-lbs. second time around. (I went around a second time at 120 in.-lbs. just to make sure I didn’t miss anything.)
It’s normal to get a little squeeze-out, which can easily be wiped off when wet or trimmed with a blade after it cures.
And here’s the final product:
And that’s it! I hope that you found this helpful, and good luck on your own vehicle maintenance and repair projects!
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