256/239 Rear Main Seal

indyhac

Member
Does anyone know if there is a procedure for replacing the rear main seal in the 239/256 y-blocks without taking the engine out of the car? My shop manual only explains it with the engine out. Some of other my other brand shop manuals explain it with the engine in the car but not my '54 Mercury shop manual. :confused: Thanks, Scott
 
There is a 2 piece tool made by Lisle you can get at NAPA to do it,you drop the oil pan remove the rear main cap one tool will pull out the old seal and the other puts it in.You may get more info on www.y-blocksforever.com I'm not sure if the newer neoprene seal for a 292 will work on the 239 if it will it is better than the old rope seals.
 
In my experience, the lower seal holder itself is often where the leak occurs. Make it very clean, and use a small dab of modern silicone on all surfaces, and the threads of the two bolts. Also, the rear center pan bolts go into oil where they can leak.
 
A "million" years ago my dad had '54 wagon with the 239 Y block. I remember him replacing the oil seal by raising the car on a borrowed fork lift and dropping the pan. It was real hassle to get the pan out but he managed. I don't remember if he was able to replace both the upper and lower or just the lower.
 
You can gain additional oil pan clearance if you unbolt the idler arm so the center link will drop down further.
 
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