Has anyone changed the main seal while the motor still in the car from underneath. Pull the oil pan, main cap and fish the old seal out and replace it with the new. Possible? Thanks, Eric
My mechanic just did mine a few weeks ago! Yes from underneath...he ended up needing 2 different seals. He combined parts of both since each didn't have everything needed. It's the second time in 20 years it's been done. Both from underneath. The mechanics were experienced both times. I had other shops say they couldn't do it from underneath, including a Buick dealership, stating that it could end up getting into a rebuild of the engine. I'm no mechanic so I can't give you the specifics of how it was changed, but definitely from the underside!
My guy has done it on chevy motors before, but he’s curious as to whether it’s the same type of deal on a Buick motor?
http://www.v8buick.com/index.php?threads/rear-main-seal-replacement-instructions.115596/ A good read. I am about to do mine during my next oil change.
I was able to clean out all the rope seal remnants and "roll in" a rubber seal. Afterwards the seal never leaked again. It was a tough way to go about it - laying on the ground in a driveway, but, it did work well.
It may take several hours to remove & reinstall the engine + tranny. It is well worth the extra work to replace the rear main seal. This past May, we removed the engine to replace the rear cam plug (leaking) & to replace rear seal (also leaking). Since we were having a difficult time installing the seal, we determined it was best to loosen the main caps, lift the crank and install the seal & retorque the mains. No leaks.
Yes, it can be done. I did mine last summer. I already had the car on jack stands with the transmission out. I cut a board the right length to prop up engine at the starter. There's not much pressure there, mostly kind of balances the engine. Once I took out the pan bolts, I was able to slide the pan out towards the back. Be careful pulling the pan around the oil pick up. You may need to rotate the crank to get the counter weights to clear easier. Remove the cap bolts and pull out main cap. I also loosened the other caps just enough to pry crank down a little. Makes it a little easier to get the new seal in. Cleaning the groove and other areas where cap goes back is kind of a pain, but just takes patience and a little time. I used the cap to size the two halves of the seal. Placed the seal in the groove of the cap and trimmed the ends flush with flat surface with a razor blade. I ordered the neoprene seal from T/A, but you can use a Ford 460 seal also. They are exactly the same, even have the same part numbers on them. I can't remember for sure, seems like I put a little oil on either the crank surface or lip of the seal. (Maybe somebody will chime in here) Rotate the top half of the seal into place with the joint offset from the joint in the block and cap. I put a dab of Right Stuff on the ends of the seal where they meet and rotate the lower half into place. Make sure to install them with the lip facing the front of the engine or it will leak. I also put a thin film of Right Stuff on the mating surface of the block and cap. Re install cap and torque, and re-torque other caps. The kit from T/A comes with rubber wedges and pins that fit in the grooves on each side of the cap. Also has a good instruction sheet showing seal orientation and how to do the work. You may need to sand these down a bit to get them in. Still will be a tight fit. More Right Stuff on these and push them into the grooves and drive in the pins. Pan can go back. I used a thin bead of Right Stuff on both sides of the pan gasket. So far I haven't had any leaks. Not sure if this repair can be done with transmission in place, but I'm sure it would be harder. Having the transmission out gives you a lot more room to get the pan off as well as room to work on the seal. For me, this seems easier than pulling the engine and all that goes along with it, and getting it on an engine stand so you can turn it over etc. Of course if you already have an engine out it is way easier to do the seal itself on the engine stand. I had already installed a new seal before installing the engine, but had it backwards and it leaked. That's why I ended up doing the seal from under the car. Only took a few hours. Good luck on yours.
Gentlemen - thanks for all of the info. Sounds like with a little bit of a surgery the main seal can be replaced with the motor still in the car. The good thing for us - we have access to a lift. I should be able to finish the summer and the fall for cruising, then pull it into the garage in the winter and work on it. Thanks agian.
There are a couple of good threads on this project. One by JW, and one by sean Buick 76 (link is in post #5) Both of these were helpful.
Yep, used the BBF 460 seal fits like a glove. Perk of the SBB is the pain rail is flat all around, only obstacle is the pickup (might as well change that gasket as well, check general condition of bottom end, etc) and the counterweights.
You need the regular 350 rear main seal and the 460 Ford neoprene seal also. Oil pan gasket, pickup tube gasket too. The side seals from the regular kit will be used as it comes with a rope seal. Loosen up the fan shroud bolts and take off the neg. battery cable. Take out the long motor mount bolts and lift up on the harmonic balancer with a block of wood under it. Oil pan bolts and pickup tube and take the oil pan out. Windage tray unbolt it, remove the rear cap , it will have to be wiggled loose using the removed bolts for leverage. Clean up all your stuff and use sealer on the face of the cap to the block . I fished out the rope seal, it was in the pan. My car had zero seal left in it. The side seal instructions are in the kit. Use sealer, ultra black or Ford grey on the top of the side seals and drive the metal spikes in . Use sealer on the pan gasket and in the four spots that have seams on the front cover and on the rear cap. Lube the neoprene rear main seals before install and stagger the seams if you can. Use a thin bead of sealer inside the rear cap on the seal back as it helps the seal from spinning when dry.... Don't try to start it the same day you do the work, if the sealer dries it probably has a better chance of being more permanent . Use high zinc oil , Valvoline Racing or that type of old school oil.
Good points 1970 Stage 1. I forgot to mention the windage tray. If you get the rear main seal kit from T/A it includes the side seals. It ended up being cheaper than buying just the 460 seal from NAPA the first time around.
