440 rear main seal leak?

[Vodoo Child]

I have a 70 Challenger with a 440/727TF. I think the rear main seal is letting go. After 10 minutes of idling in the garage I have about a 3 inch puddle of oil on the floor. I jacked it up and took off the tin dust cover on the trans. the oil is coming out of the bell on the trans. The little bit I can see up into the bell of the trans. with my droplight the top inside of the bell looks wet. There is a 933 oil pan on the car now that has seen better days. I'm thinking of using Mancini's billet rear main seal retainer part#MRE223 and replace the oil pan with Mancini's 402 pan part#MRE402. First off I know I have to pop off the steering rod under the oil pan. But will the oil pan come off so I can get to the rear main seal and change out the 933 pan and put on the new 402 pan. I'm assuming the pickup in the 933 and 402 pan's are the same. Any tips or info would be helpful. Thanks     

[cudabob496]

Make sure source of leak is not the fittings on the upper back of the block where
oil is sent to the oil pressure gauge.

[Vodoo Child]

Make sure source of leak is not the fittings on the upper back of the block where
oil is sent to the oil pressure gauge.

That area does ooze some oil. I put a brass T below the sending unit to tap off of for the under dash oil pressure gauge. I'll start there first. I called Mancini about swaping out the pans. The tech guy told me the motor will have to be raised at the minimum if not come out to change the rear main seal. And the pickup from the 933 pan wiil not work in the 402 pan. 

[mopar jack]

I have removed the pan on my 71 cuda/440/auto many times and never lifted the motor. Just pulled the drag link from pitman and idler arm and let it hang. Replacing main seal is not hard, just clean and follow instructions. It would be nice if the tranny and flywheel were out of the way so you can put a bead of sealer on the outside of the seal block but not required. I recommend to drain oil from pan and let sit for a couple of hours. Then pull pan and wipe off oil as it drips, eventually it will be dry enough to work on.

[Racer57]

Can the same be done with a 383 Cuda ?  Mine is leaking more than I care for.

[5spdcuda]

    Rear main seal leaks seem to be a common complaint on big blocks. I think part of the problem is that many people aren't old enough to have read the proper factory procedure for seal installation. First of all they were originally designed to use a rope seal [ so were small blocks ]. Next and most common is improper side seal installation. The side seals do NOT go in dry. Regardless of whether or not you use a newer rubber seal or the older rope type the side seals should be soaked briefly in kerosene or diesel fuel and then QUICKLY installed. The kerosene will cause the seals to expand tightly thus sealing the area between the seal holder and the block. Once the side seals are soaked speed is essential in order to get the seal holder in place before the expansion makes it impossible to install. If you install them dry hoping that the engine oil will cause sufficient expansion to seal things up, well good luck. Seriously they will usually leak. You can also take a flat file lightly to the top of the seal holder and remove .002-.005. This will seat the holder a bit more tightly to the block. Don't go crazy with this or you will have an oval seal instead of a round one. When all else fails Indy makes a replacement seal holder with rubber side seals instead of the factory fiber ones.

[Chryco Psycho]

If you can still find a seal with the side strips all the ones I have purchased lately have pipe cleaners instaed of side strip what the heack do you do with a pipe cleaner ? I have gone to using Right Stuff sealer & putting a bead inside the pan between the block & seal plate on a 45 * angle & simply sealing it up from the inside .

[cudabob496]

I've read that in engine assembly, there are ways to re-route oil discharge from
the oil pump, away from the main seal area, to minimize leakage, but never done it
myself.

[Chryco Psycho]

Can the same be done with a 383 Cuda ?  Mine is leaking more than I care for.

Yes , same bottom end

[2fast4uchallenger]

Good afternoon guys, this is my 1st post so I hate to sound ignorant. But I have just installed my rebuild 383 in my 71 Challenger. Fire it up for the 1st time and guess what .... an oil leak. I've got it narrowed down to the rear main seal.  I have looked everywhere and I'm having a tough time finding out if I need to drop the transmission to change out the seals? Can you all give me a hand? Thanks in advance.

[Chryco Psycho]

no need to drop the trans , drop the steering link , remove the pan & the seal plate will unbolt with a 3/8" 12 point socket , I used to use the Fel Pro seal but they replaced the side strips with pipe cleaners not sure how that si supposed to work , you may be able to use the old side seals though .
 I use right stuff sealant & run a bead in the corner between the seal plate & block , you will need a long small screwdriver to get the bead in there but it works , offset the seal 1/2s so the ends are not even with the block , a small amount of sealer between the plate & block & on the seal ends , take your time & it will seal .