I just bought a rig with a 327/350 w/ th350 in it... I noticed a slow but steady leak of oil coming out of the back of the motor when it is on, and right after shutting down... I assume it is the rear main seal (its not the heads or valve covers... I crawled under and checked it out and it comes from right in between the block and flywheel...

I have never replaced a main seal but am replacing my tranny this weekend; Should I do the main seal myself or pay someone? I will already have the tranny out - is it just a matter of dropping the pan and pulling the flywheel???

Is the rear seal 2 piece or 1 piece? How does it go on???


Thanks in advance for any help!

This is usally easy,
the seal is a two piece, and the only things to be removed are the oil pan ,oil pump & # 5 main cap. once you have the engine up & the pan off, remove the oil pump & drive shaft, then remove the cap from the block.
once you have the cap in your hand look at how the seal in sitting in it. it should be facing inward towards the bearing insert. the upper half will roll out when you push on it,don't use anything sharp, I have screw driver cut off and sanded so it won't mark the crank. sometimes you have to really push to get it loose depending how it was installed. once its sticking out about an 1" then grab it with pliers and rotate it out the rest of the way. it should have been facing inward also.
clean all the bearing cap & seal mountings good with brake cleaner & an old tooth brush. the new seal will sit snug, so spray a little oil on it so it can settle in without binding. rotote the upper half in by hand and use as much oil as you like to get it in(seal lip facing forward). once its up and in place let it hang out on one side so it can overlap into the cap(about 1/4 ") the same goes for the one in the cap. it should stick up on the opposite side. add some thin sealer like form a gasket or high tack to the steel surface on the cap and install. then tighten the bolts to 80ft.lbs in 15lb increments. then reinstall the oil pump and tighten to 65 ft.lbs .
I will say this, if you bust the plastic retainer on the oil pump drive shaft, go buy a new one! don't try and install it without a retainer.

once you have the bottom back together you can reinstall the oil pan. I use spray trim adhesive to hold the gasket to the block and then rtv the ends of the rubbers to hold them up. the pan should be free of any debris and the rails flat & clean.
have fun

Awesome writeup, yetti.

Couldn't have said it better myself.

MANY THANKS TO YOU YETTI!!!

This sounds like something I can do this weekend when I swap my tranny!!!

I AM SO STOKED!


Quick question though; I am a total newb... Will the oil pump and shaft be an easy removal? I mean I see how to pull the pan (20 or so bolts around the edge) but never pulled an oil pump? I assume it is probably just 2 or 4 bolts holding it in, and the shaft is probably a hex or square shaft that just pulls out freely once the pump is out???

Oh and when installing the #5 cap, What kind of pressure do I torque it back down to? I assume this is a critical piece of information? Is there a certain procedure (order of bolts etc...) that it needs to be cranked down on? I think it is just a 2 bolt main so I assume it doesn't matter???


THANKS AGAIN -- YOU WROTE THAT SO WELL I AM SURE I CAN DO THIS!!!

~Chad

then tighten the bolts to 80ft.lbs in 15lb increments. then reinstall the oil pump and tighten to 65 ft.lbs .

This is in there , I was discribing how to reistall the #5 cap.

as for the oil pump its a single bolt and the pump has a guide pin to dowel it into position. the oil pump drive shaft has one slot to engage the distributor shaft(and its round), so you might have to turn it a bit to get it in. the single bolt screws into the #5 cap in the center. the shaft slides through a hole on its edge. the pump can lose its prime if washed so pour some oil in it and turn the shaft by hand to get it in the gears.

Just a funny bit of info, I had a engine get brought in one time as a basket case. It wouldn't turn over after it was assembled and torqued. the guy put a short "head" bolt in the oil pump bolt hole(1/8" difference) it stuck the crank bearing to the crank and wouldn't budge. so think about every step and keep your parts in order.