• KulAdventures

1975 Ford Bronco - How to Remove Rear Main Seal

During the course of my Holley Sniper EFI update I realized that I had an oil leak out of the rear main seal that needed to be addressed. As these engines (1975 Ford 302ci V8) use a two piece rear main seal, it is "possible" to replace without removing the crankshaft, however it is not easy. And to ruin the end of this story, my main bearings were also in bad shape and even if they were not bad, main bearings are not that expensive and were very easy to replace so if you are in this deep, I would really recommend changing them out (More on that to come in another post)


Parts:

-Rear Main Seal

-Oil Drain Pan Gasket Set


Tools:

-Sneaky Pete Rear Main Seal Tool

-PB Blaster or similar lubricant

-Sockets and Wrenchs

-Every other pulling/pushing device you can think of


Just a sneak peak, these are the tools I needed to get the rear main seal upper section out:



First thing to do is remove all the oil from the engine and then remove the oil pan. This requires all the exterior bolts and removing the oil dipstick. Once removed set aside the seals and the oil pan. I used this time to clean, sand, and repaint my oil drain pan as it was in really bad shape.


Next I would loosen all the crankshaft bearing holders, not completely, just enough to allow clearance for the crankshaft to move slightly. Remove the rear main seal bottom half and set aside. There is a pin in this that holds the old rope style seal in place and will need to be ground down and removed. When I removed mine it was the original rope style seal and you will notice that the new seal is similar to the rubber seals used everywhere, which will seal much better than the rope seal.


Here is a picture of the new seal installed in the rear main seal bottom half (near bearing is installed already... more on that later)

Now comes the hard part, and let me just say there are a lot of things you can do to get the seal out and some may work in your situation, some may not. Just keep in mind you are trying to remove an oily rope from a narrow curved crevice that is flush against metal. Its not an easy thing to do.


This is what that approach looked like:


Here is a list of things I tried to do to get it out (all methods used lubricant in the area, I use PB Blaster):


1. Screw a screw into the rope and pull the screw out with vice grips (careful not to scratch sidewalls) - Worked, grabbed well, but tore the rope seal into small pieces


2. Buy a Sneaky Pete tool (similar to a corkscrew) and use that in a similar manor as the screw - Same results


3. Pressurized Air and Lubricant - Helped lube, but no movement of the seal


4. Pull the crankshaft down slightly to allow more room (remove crankshaft seal holder and spark plugs) - Maybe helped slightly...


AND THE WINNER (with help from all of the above):


5. Take a piece of copper brake line and curve it into the hole, use it to push the seal through and use an air hammer with a blunt tip to pound the brake line into the seal - Worked, but hard to keep the brake line straight and not kinking, still required the sneaky Pete corkscrew to remove bits of the rope seal at the end.


Copper Brake Line in Seal Area

Once out make sure to clean off the area a ton with cleaner and pressurized air to make sure no rope seal remains.


Next install the new seal by heavily lubricating the area and seal and installing it where the old one was, making sure to pay attention to how the seal orients (lip faces in towards the motor). Mine took some convincing to get it in, but be very careful not to damage the seal. I actually purchased two seals the used one of them to push the other in. One got heavily damaged in the process and was used as the pushing one.


Once in place make sure to have them offset and not aligned on the metal seam and install the lower one, only after replacing the main bearings (more on that to come).


Once the engine is all back together look for leaks and periodically check the area.

1 view0 comments

Recent Posts

See All