I know this has been kicked around some in the past but I am just about to start my bottom end clean-up project what with rebuilding the oil pump and engine vacuum pump and needed some clarification on the best way to install a new rear main seal with the engine and dynaflow transmission still in the car. Now if it would be loads & loads easier to do this with the transmission out, that can be done since dropping the transmission is on my to-do-list for resealing and could just wait on this until the transmission is out. So here's my plan. I will remove the lower main caps while supporting the crankshaft. I have the front timing gears off now so the front shaft is free. This should allow me to lower the crankshaft by about an inch or so to install the new upper and lower section of the rear main seals, then bring the crankshaft back up. So, does this sound like a workable scenario? Any advice or to watch out fors? It seems I did this years ago in high school with an old flat head six I had souped-up and needed to replace the rear main seal and it worked out just fine back then. Any advice would be appreciated. Thanks in advance. David
The way I read it in a Chilton's manual years ago was to do essentially what you're doing now. They left the crank and motor in the car, and backed off the end cap, but let the crank hang. The transmission and motor were still in place and hooked up. They then worked out the old seal, by pushing and pulling, and worked a piece of wire into the new seal (through the centre of it) greased it, and then fed it around the crank and pulled the new seal into place. Once the seal was in place, clip the ends off and replace the lower cap and torque up. I've never tried this, but have been told it works. How well and how long, is anyone's guess.
Thanks. I am going to be using Best Gaskets seals and not the original rope. If I cannot get the lowering I need by just removing the mains and pulling down on the crank with the rods still connected, I was thinking that since I have everything out of the way I could just as well drop the crank out by taking the rod caps off too?
My "Neoprene" rear main comes with directions & the sealer that I use. Using my method & following instructions you DON'T need to loosen the mains OR drop the crank. The hardest part is removing the original rope seal. The new seal is easier to install than removing the old seal. Just need guidance & direction & little details make the difference.
Hello Tom. What year Buick do you have and who makes the seals you are referring to with all the instructions? Getting the old seal out would be all but technique and yankee ingenuity. Most likely would need to improvise some pliable tool to chase the old seal out and get the new one back in proper and not twisted. Back in the day you could buy a tool for this that was like a thick stiff cord with a wooden handle on one end.
A real GOOD pair of needlenose pliers. Grab ahold of one end & turn the crank while pulling. Most of the instructions are hand written.
I've done a bunch of these over the years and would check one more thing. See if the original rear main is actually leaking first. The tranny is almost always the leaker followed by the oil sender, valve covers, oil pan or the intake manifold rear seal. Bottom line, if it turns out the rear main is good I wouldn't touch it. While that job can be done on your back, The chance for problems is high. As easy as it is to just pull the motor I would think about going that route should that seal need replacement. Just my 2 cents........... Steve weim55 Colorado
I also include a small tool/detail part to aid installation. NOBODY else includes directions, sealer or a tool. The intake manifold CAN'T leak, but the valley pan under the intake can. I can ALSO supply the replacement front seal with instructions included.
Duh...... Tom you are correct. The valley pan seals that area on a nailhead, not the intake. I can add a little more experience........ The new replacement rope seals are not made up of good stuff of seals yore. Hence the new rope seals commonly leak even with proper installation. Should you elect to go rubber route make sure as Tom says to get a seal from a proven nailhead source. From somebody who has actually installed their own goods with success and knows all the little nailhead details. I've had many a problem with seals sold by proper size dimensions only to find isssues with the seal hitting the knurled edge on the crank surface, thrust bearing interference etc.... Steve weim55 Colorado
Thanks guys. This car has sat for some 40 years in a garage and if I don't reseal, it will leak sooner if not later. I am bringing the car back to life and this is on the to do list while I am in the underbelly. You are correct, I could just pull the engine and do the work but wanted to hear from any 55-58 heads that have done this in the car to see what do's and don't - do's worked out best. Not too interested at this point in pulling the engine. Besides, that would be a lot of gymnastics as well. Most likely would be a lot easier with the transmission out of the car don't you think, so if I don't hear to the contrary, I will most like drop the dynaflow and proceed with dealing with the seal. Just don't want to have to drop the mains or the rod bearings IF I don't have to so if anyone has done this please let me know.
