FYI FORD MustangSteve's Ford Mustang Forum / Rear main seal?

**Posted by Rudi** 7/02/2024 7:03 PM

I have developed a small seepage at the rear of the oil pan and from the best I can determine it’s the rear seal. I am using 5w-40 synthetic and have 55 # oil pressure cold, 45 # hot.
I hate any kind of leak and usually try to correct them toot sweet.
Now the leak is not all that bad and at this time there is no way I am replacing it, it’s an 86 5.0 block and quite sure a one piece seal.
My question is should I use some Blue Devil seal repair in the oil or just live with it till winter shut down.

Last edited by Rudi (7/02/2024 8:17 PM)

**Posted by Ron68** 7/02/2024 11:54 PM

Got a rear main seal leak on a Jeep Grand Cherokee 4.7L that was a long block rebuild. Put in a bottle of Blue Devil. That was seven years and 24K miles ago and no leaks. Sealed up within just a couple of days and been good ever since.

**Posted by TKOPerformance** 7/03/2024 5:32 AM

A buddy of mine has a truck he bought used and it had a RMS leak. He put some Blue Devil in it and the leak went away. He was telling me about it when he was over at my house. When he left I noticed a decent sized oil spot on my driveway. The next day I told him about it. It was leaking again. No idea how long it worked for, but IMO those types of fixes are designed for the guy selling his vehicle. They generally work for a while, but eventually fail.

**Posted by BobE** 7/03/2024 6:37 AM

Suggest verifying the leak is not from the valve covers, the intake manifold to china wall area, or a oil pan bolt before changed the rear main seal.

**Posted by Toploader** 7/03/2024 7:17 AM

For a few years, I was convinced that I had a rear main seal leak and just lived with it, as much as I hated it.
I recently changed my sump plug and washer and discovered there was no more leaking.
I no longer have any drops of oil.

**Posted by Steve69** 7/03/2024 7:58 AM

Check your oil pan bolts too. Maybe they have loosened a bit causing the leak.

**Posted by Rudi** 7/03/2024 9:23 AM

Other than the sump plug I checked all the usual suspects before I posted.
The engine has about 30,000 miles on it.
I wonder how the rest of the seals in the engine would react to the Blue Devil elixir?

Last edited by Rudi (7/03/2024 9:25 AM)

**Posted by 6sally6** 7/03/2024 9:58 AM

I'm sorta hesitant to use the "mechanic-in-a-can" stuff......I've used it butt.
Rudi...after all it IS A FORD and like Harleys they like to mark their territory !
Cat litter is your friend until winter and then........if you haven't accepted the fact...pull the engine...replace the seals...install a radical roller cam (you only live once!)...a set of AFR heads (to take advantage of the superior breathing!)...make plans to drive it to MB to cruise it...come give me a ride....park it in my driveway...and vidit and enjoy life this winter !
NOW THERE'S A PLAN !!!
6sally6

**Posted by Rudi** 7/03/2024 10:27 AM

Sounds like a great idea Mike, if only I was up to the task.

**Posted by MS** **Online!** 7/03/2024 10:37 AM

I used that stuff on my 427 a long time ago. Seemed to help for a while but eventually put a new seal and crankshaft sleeve in it.

I highly recommend the FelPro crankshaft repair sleeves, even if there is no apparent damage to the crank. Never had any seepage after installing a sleeve. I even put one in my brand new 331 crank for the 65.

**Posted by Rudi** 7/04/2024 8:40 AM

Other than dropping the transmission can a one piece seal be r&r , oil pan in place?
How about the Fel Pro sleeve at the same time?

**Posted by MS** **Online!** 7/04/2024 2:40 PM

That is the beauty of the one piece seal. Remove flywheel and block plate.
Drive a #6 nail into the seal body. Remove nail and put a 1” long sheet metal screw in the hole. Grab screw with vise-grips. Pry out the old seal.

The FelPro sleeve requires a special tool, about $30, made of plastic. If you know a good machinist (!!!), they could probably make one. I can send you the dimensions.

Use red loctite on ID of sleeve.

Lube the new seal and push it into the block, being careful to not shave off any of the OD. A PVC fitting, 4” pipe plug works great as an install tool. Or, whip out your lathe again…

The block plate keeps it from coming out of the bore, along with the tight fit of the external rubber ribs.

You know the rest of the drill.

**Posted by Rudi** 7/04/2024 7:46 PM

Thanks for that great write up,I would like the installation tool dimensions please..
Any way to make that info a sticky?

**Posted by Rudi** 7/06/2024 8:33 AM

Excellent, you da man Stevo!

**Posted by MS** **Online!** 7/09/2024 1:14 PM

This drawing has all the needed dimensions to make the #16300 installation tool for the Fel-Pro 289/302/5.0 crankshaft repair sleeve #16250 or #21-2100

**Posted by Greg B** 7/09/2024 6:39 PM

We need a dedicated spot for popular part numbers for seals and gaskets and such. Googling anymore seems to bring up answers that are completely for different engines.

I know the tool for 351 sleeves is discontinued. I was trying to find the part numbers for the 351 sleeve and tool and seal. Just to keep them all in a handy location.

I remember Felpro recommended the regular seal line with repair sleeves and not the premium material.

**Posted by BobE** 7/10/2024 6:37 AM

Greg B wrote:
We need a dedicated spot for popular part numbers for seals and gaskets and such. Googling anymore seems to bring up answers that are completely for different engines.

I know the tool for 351 sleeves is discontinued. I was trying to find the part numbers for the 351 sleeve and tool and seal. Just to keep them all in a handy location.

I remember Felpro recommended the regular seal line with repair sleeves and not the premium material.

I installed a rear main seal & sleeve on my 351W in 2014, still no leaks. To my knowledge the below parts are still available.
Sleeve: Victor Reinz # A332
Installation Tool: Fel-Pro #16301

**Posted by 6sally6** 7/10/2024 11:06 AM

With Rudi's unlimited talents in machining... why don't we ask him to machine these parts that are no longer available ?!
He would be compensated for his talents and we would be able to receive custom pieces that may not be available on the open market !
(I love to "volunteer" other peeps talents !!!)
6sal6
This^^^ is my way of forcing Rudi and Lyn to come to Myrtle Beach this winter. He will gladly come just to punch my in the nose for my volunteering antics !! 6s6