1st time questions on replacing the rear main seal.

FastSVO · Jun 23, 2007

Hey guys,

I've been reading past posts and the FAQ page on this job, but still wanted to go over the process in detail.

I have purchased the Fel Pro 2 piece racing (VITON) rear main seal and the one piece rubber oil pan gasket designed for early 289/302 pans.

NOTE: My existing rear main seal is about 11 years old.

Now, do I really have to loosen all the main caps or can I just get away with removing the rear main cap by itself?

I am assuming I can easily pull the upper half of the old seal off?

The installation methods that I have read seem to go back and forth on wether to install the seals dry or with oil and the possibility of damaging the seal during installation. This is where I am most concerned about doing this job. Any advice in this area would be greatly appreciated.

Now about using RTV...I understand that I will put a small glob on the corner of the cap (right behind where the seal protrudes from -facing the tranny). What about adding RTV behind the lower lip of the seal facing the tranny as well?

When retorqing the main cap, which torqing procedure is recommended?

Now over to the 1 piece rubber pan gasket....just goes on dry?

As you can see I am a little confused and need some direction on the job! Thanks in advance.

-Eric

D.Hearne · Jun 23, 2007

I have never done a rear main seal in the car, but you may need to loosen all the main caps, depends on how difficult the old seal is in coming out. Chances are it's not a rope seal being only 11 years old. A dab of sealer under the rear main cap won't hurt . Retorque the caps from the middle cap outward. The one piece gasket goes on dry. There should be some plastic installation studs to hold it in place while you install the pan. If you can, locate a set of late model pan rail stiffeners from a 80's-up 5.0, these help to eliminate the pan rail warpage. You'll need the longer bolts that go with it as well if you go that route. Also make certain the lip of the seal faces toward the inside of the motor when you install it.

pabear89 · Jun 24, 2007

You can replace the seal by just removing the rear main cap.
the cap has half and the block holds the other.
take a small rod and push the seal at one end,
it will roll around the crank and stick out enough to get ahold of it.

When removing it do not try and pull straight down but work it around the crank.
Install it with a small amount of oil to lube the seal and slide it around the crank and seat it flush with the block.
A dab of sealent on both ends of seal and reinstall the cap and tork.

Dh has covered the oil pan.

PB

Rusty67 · Jun 24, 2007

I suppose if you wanted to, you could yank the crank and have it machines for a 1 piece rear main seal then put it all back together and stick one of the new felpro seals in that have a teflon seal. I'm running late model 5.0s so I already have a 1 piece seal (lucky me).

Altho it is more work, you may want the 1 piece seal. If not, you are already covered with how to do it so good luck.

FastSVO · Jun 24, 2007

Thanks for the responses guys!

D.Hearne · Jun 24, 2007

Rusty67 said:
I suppose if you wanted to, you could yank the crank and have it machines for a 1 piece rear main seal then put it all back together and stick one of the new felpro seals in that have a teflon seal. I'm running late model 5.0s so I already have a 1 piece seal (lucky me).

Altho it is more work, you may want the 1 piece seal. If not, you are already covered with how to do it so good luck.

Ain't gonna happen with a 2 pc seal block.

Rusty67 · Jun 24, 2007

I heard you can just machine the crank, is the block different too ?

D.Hearne · Jun 24, 2007

Yea, the block is cast and machined differently at the rear to accomodate the 1 pc seal. Ditto for the cap too. One drawback to this is it makes the part of the cap that encases the seal fragile. I've broken two rear main caps in that area. My machinist welded one back, the other will be as well if and when I ever use it. The break and repair isn't a biggie as the oil pan keeps everything in place and there's no stress on the cap from the seal.

FastSVO · Jul 3, 2007

UPDATE:

I replaced the seal over the weekend and it wasn't as scary as first perceived, but only time will tell if I did a good job. As a note, I torqued the main cap to 70 ftlbs....I first set the Autozone rented torque wrench to 30# and it kept going and didn't click...it just got harder to torque down...so I backed off...set it to 60# and immediately got the clicking noise...so I decided to back off the bolts and start again...eventually torquing the main cap to something that felt like 30# and then to 60# and finally to 70#. I let it sit for a awhile and then I again attempted it with the torque wrench set to 70# and immediately got the clicking noise (just in case if that bolts had stretched). BTW, I dipped the main cap bolts in 20-50W before I reinstalled them.

Does it sound like I did it correctly?

Thanks,

65ShelbyClone · Jul 3, 2007

Do you have a repair manual? Even a Haynes(which is often more useful as toilet paper than a manual) actually has the specs and sequences for working on smallblocks. I would also be leary of that rented torque wrench. You can get a Craftsman beam type for about $30.

But yes, you used the correct torqing method.

SCHOONER · Jan 4, 2008

I was told it a little bit differently

pabear89 said:
You can replace the seal by just removing the rear main cap.
the cap has half and the block holds the other.
take a small rod and push the seal at one end,
it will roll around the crank and stick out enough to get ahold of it.

When removing it do not try and pull straight down but work it around the crank.
Install it with a small amount of oil to lube the seal and slide it around the crank and seat it flush with the block.
A dab of sealent on both ends of seal and reinstall the cap and tork.

Dh has covered the oil pan.

PB

Hi Pabear89

I liked what you said and it makes good sense to install the rear main seal the way described it.
However, I was told that with a 2 PIECE SEAL. You should make sure you push the seal about 1/4 to 3/8's of an in. up pass the crank.
This way the seam and the both engine part are not in one line with each other, making it more of a LEAK proof seal.

I haven't install mine YET. But that little trick sure makes sense to me.

Thanks for you imput
GOD BLESS

Schooner

FastSVO · Oct 1, 2008

Resurrecting this thread....

I installed the seal as described above (not flush) and did add a dab of sealant on the end caps (not on the ends of the seal itself).....fired up the motor and a couple of hours later, noticed that it's leaking from the RMS.

Hmm...I am going to get this right eventually! Should I just pull the cap and try adding sealant to the correct places and see if that will work? Or go ahead and buy a new RMS and replace that as well?

Thanks,

Eric

Rusty67 · Oct 1, 2008

First off, are you working on a motor with a 2 piece or 1 piece rear main seal ? Second, are you sure it is actually leaking from the seal ? Third, did you check the crank snout for burrs ?

Edit:
Just realized you have a 2 piece seal.... DUH.

D.Hearne · Oct 2, 2008

You may have installed the seals backwards. There's a lip on the seal that rides against the crank surface, that seal lip faces towards the inside of the motor.

FastSVO · Oct 3, 2008

I am pretty sure I installed it the correct way. Are there any pics online that show how and where to apply the RTV on the seal?

Thanks,

Eric

BarnStang · Oct 3, 2008

Don't forget the flywheel bolts. THey need to have sealer on the threads. The backside of the flywheel bolts are exposed to the crankcase oil. x2 on setting the seal in offset-keeps the seam away from the main cap seam.

D.Hearne · Oct 3, 2008

BarnStang said:
Don't forget the flywheel bolts. THey need to have sealer on the threads. The backside of the flywheel bolts are exposed to the crankcase oil. x2 on setting the seal in offset-keeps the seam away from the main cap seam.

The flywheel bolt holes only go thru to the crankcase with the 50 oz/in cranks, the 28's need no thread sealer.

TOM B · Oct 3, 2008

D.Hearne said:
The flywheel bolt holes only go thru to the crankcase with the 50 oz/in cranks, the 28's need no thread sealer.

AH, thats wrong. I have several 65 cranks with 28 oz and all of them have the holes open to the oil.

D.Hearne · Oct 4, 2008

TOM B said:
AH, thats wrong. I have several 65 cranks with 28 oz and all of them have the holes open to the oil.

Those are the first I've heard of then.

TOM B · Oct 4, 2008

Here is a SB Ford Boss 302 1969.
Open holes.

1st time questions on replacing the rear main seal.

FastSVO

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