So, does everyone have a leaking rear main seal

[jbickhart]

I'm on my 2nd attempt with a new 2-piece seal. I spent at least an hour cleaning everything, sealing the seal ends with silicone, sealing around the cap with silicone and a new 1 piece oil pan gasket. The crank sealing land is in perfect condition. I'm getting really sick of the hot fresh oil smell!

 

[siderbox]

Went to the doc a few months ago. All good now.

Oh wait...

 

[Ovalis]

Do you line up the seal flush with the block?
I rotate the seal so part of it is sticking up out the block and the otherside is inside the block. Do the same with the other side inside the cap.

 

[jbickhart]

I offset each half of the seal about a half-inch from the plane where the cap meets the block and added a small shot of silicone at the joints.

What else is there other than RTV silicone with adhesive.... that's what I used?
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[Revelation]

Been driving mine for over 2 years, 16,000 miles, still park it in the garage, and not a drop has ever been left from anything.

 

[half cab]

I get worried when mind don't drip something

Oh and that hot oil smell...I been smellin that for 25yrs....I don't leave home without it;D

 

[blubuckaroo]

http://jeep-xj.info/HowtoRearMain.htm
This is probably the best write-up I've seen on the subject even though it's foe a Jeep. I have always used an anaerobic sealant rather than RTV for the main cap sealant. Cleanliness it of the utmost importance!

 

[ENDLIFE]

I just did mine for a second time, and not a drip on my driveway. I pulled my engine to rebuild it after an awesome hydro lock during a trip, during my break-in I got a little happy with the throttle, and cooked my seal. I borrowed a friends sneaky Pete, and went to town on my rear main seal. However, it was next to impossible to offset the seal without dropping the crank, but Jeep seals aren't offset so I figured I would be okay. Not a leak yet.

 

[Nobody]

Make sure the pcv system is hooked up properly and working! On a healthy engine there should be negative pressure in the crankcase. There should be slight suction on the clean air side of the pcv system. A lot of people screw up the pcv system with aftermarket parts. You can change rear mains all day long, and it won't help if you're building pressure in the crankcase.

Also make sure it's not oil running down from the rear intake manifold gasket.

 

[redtail]

I did mine in the rig and offsetting it made it worse, or I may have scraped the gasket as it was offset going in (the main cap part had a little tab up and I think it may have scraped off some gasket there. I also had little peg in the bottom of the main cap that I think may have been left over from an older style rear mail seal? It leaks a quarter sized spot overnight, but that's the only engine oil leak as of now... aside from the dist gasket not being installed %)

 

[jbickhart]

Nobody,

Ill double check my pcv system. Im using some of the stock mustang system but I plugged the pcv port in the manifold and added a pcv valve to the valve cover. Ill run a breather in the other V/C for a while and check the leakage. I leak from the front crank seal which is also new.....


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[Mikey]

Make sure the pcv system is hooked up properly and working! On a healthy engine there should be negative pressure in the crankcase. There should be slight suction on the clean air side of the pcv system. A lot of people screw up the pcv system with aftermarket parts. You can change rear mains all day long, and it won't help if you're building pressure in the crankcase.

Also make sure it's not oil running down from the rear intake manifold gasket.

...or the back of the valve covers.

I believe there are two different PCV valves...one for the old open system (PCV side into base of carb, other to open filtered push-cap in valve cover) other for newer closed system (PCV side to base of carb, other side to air cleaner). The old system is easily identified with an open element air cleaner and the newer by the enclosed snorkel air cleaner.

Many pull off the snorkel set up and replace with open element/vented oil cap set up without changing the PCV....sometimes causes some problems.

 

[707Bronk]

Do you line up the seal flush with the block?
I rotate the seal so part of it is sticking up out the block and the otherside is inside the block. Do the same with the other side inside the cap.

X2 on that.

 

[rcmbronc]

Are you sure it is the rear main seal. I changed mine three times until I figured out it was the rear cam bearing plug leaking. Aslo I think some Ford crank flywheel holes see oil.

 

[jbickhart]

I didn't build my short-block, but if I remember right, someone used threaded plugs for the cam oil holes. This is my 1st Ford.... are the cam oil plugs threaded or press-in from the factory?