Rear Main seal procedure

[Alexander]

Hi Folks,

I am getting ready to replace the rear main seal on my 51 Dodge coronet (with fluid Drive).  Was wondering if anyone can spell out a high level procure and or in what sequence to attack the job.  I will have borrowed time on someones lift and want to be as efficient as possible with my approach.  Also any thoughts on how much time should it take?   -Thanks!

Edited November 2, 2016 by Alexander

[Don Coatney]

The procedure is explained very well in the service manual.

[Alexander]

Don-  Thanks for the post!  Glad to hear the fluid drive and or transmission don't need to come out.  How much time would you think it would take the average DIYer to do the job(very mechanical)?  Perhaps 2 hours? 

[sser2]

2 hours ago, Alexander said:

Don-  Thanks for the post!  Glad to hear the fluid drive and or transmission don't need to come out.  How much time would you think it would take the average DIYer to do the job(very mechanical)?  Perhaps 2 hours? 

Because you will need to remove the flywheel, transmission and clutch have to come out.

[Dartgame]

If your engine has the outside seal that bolts on to the back of the engine as shown in Don's attachment, you will need to pull the trans and flywheel unless I am mistaken.

I just did the same job on my 52 plymouth - it has a manual trans. I wanted to replace the 3 spd with a 3 spd overdrive and decided that while in there - the clutch, T.O., and pilot bearing should all be changed and the flywheel resurfaced . Once that far in I realized what a mess it would be to replace the leaking rear main seal if I did not do it at the same time. The flywheel covers up the upper half of the external seal and you cannot get it out otherwise. I chose to use one of the best gasket seal products- #3675 which is actually a conversion from the external seal to an internal style. Remove the oil pan, and loosen the # 2 & 3 rear main bearings (and remove the rear main bearing cap) to get some wiggle room and turn the crank to move the upper seal into place. Put some gasket dope on the groove of the seals before installing - install the rest of the rubber pieces dry and torque to spec. My motor has not been back together for long and only run for about 30 minutes, but no leaks so far, fingers crossed....oh and by the way, my main cap had a hole that would normally be covered with the external seal and would leak with out it being plugged. I plugged it solid with JB weld. Be sure to clean the main cap very well if you have to do this. I understand that not all motors have these holes drilled so you may get lucky.

Edited November 2, 2016 by Dartgame

[Alexander]

Gents Thank you all for your feedback.  I think I have been armored to try this next weekend.  Thanks again!

 

Alex

[C Michigan]

I'm trying to do the same thing with my Plymouth P15.  As usual I get to do it twice, once to learn, and once correctly.

Here is what I've learned:  Once you have removed the drive shaft (easy, 8 bolts) in order to remove the transmission ( a transmission jack is really necessary), in order to remove the clutch and flywheel, you are ready to tackle the seals.  Note that there is not enough clearance to remove the flywheel unless you tap the bolts in until they bottom out (you will gain the magic half inch that you need in order to remove the flywheel).

With your dominant arm through the hole that the transmission used to occupy, and the other arm up through the bottom of the bell housing, you can get a wrench on the three bolts holding the top half of the seal in place.  There is minimal clearance because there is a flange on the crankshaft that obscures the bolts, but by dicking around, you can do it.  the bottom half is simpler.

The stinker is replacing the top half !!  Here is what I have done.  First saw your wrench in half so that you have room to move it around in the close quarters. (The bolts are only torqued to 10  ft lbs so they are not tight.).  Next, take a small dowel (3/4 inch) and sand it into an oval.  You are going to use this as a cam to hold the seal in place while you use your hands to start the bolts.  Count on taking a lot of time to line up the holes because you cannot see up there. 

So...looking at the upper seal there are three bolt holes, one east, one west, and one north. Start either the east or west first.  line up the hole, put in your dowel cam and twist it to hold the seal in place.  Now get the bolt roughly in place.  use one of your stiffer feeler gauges against the cap of the bolt to push it against the receiving threads and carefully use your cut-off wrench to turn the bolt and catch the threads.  Next, do the same to the other east/west bolt.  this is complicated because the seal is springy and has to be held down against the crankshaft (but you have one pivot bolt in place already).  Compress it with one hand and use your cam to hold it in place while you start the bolt.  With two in  place, the third (north, is possible)

Now the Lower Seal.  Take the pan off and remove the rear bearing journal (yes, you have to because the seal is slightly egg shaped and the bottom must be slid up and compressed against the upper.  The only way to do it is to attach it to the lower journal and use the act of tightening the journal to slide the lower seal up to and against the upper seal.

patience