Front main seal replacement

SBSerpent · #1 (**permalink**) 02-17-2023, 06:33 PM

This would be on a stroked 392 (351W block). Ford Racing Motor. Need to replace the front main seal. Can this seal be replaced from the front of the timing chain cover or does the cover need to be removed (replaced from the rear of the cover)?

This is the stock motor on a 2011 build.

Any other nuggets of information regarding the replacement would also be greatly appreciated.

SBSerpent · #2 (**permalink**) 02-17-2023, 06:41 PM

I'm also a little surprised that I need to replace the seal with only 10k on the motor.

blykins · #3 (**permalink**) 02-18-2023, 03:53 AM

It can be replaced by just removing the harmonic balancer. Get a seal puller to get the old one out. Drive new one in, make sure it's lubricated well on the ID before you put the balancer back on.

Also, there are centering tools that are available to make sure the timing cover is centered on the crankshaft. If your timing cover doesn't use dowel pins to locate it, it could be that it's off-center a little bit.

SBSerpent · #4 (**permalink**) 02-18-2023, 11:27 AM

Could the leak be caused by crankcase pressure issues? I do have a PCV on one valve cover and a breather on the other so the crankcase is being vented. The only thing that I did (about 1000 miles ago) was to swap the locations of the PCV/breather (i.e. I moved the PCV from DS cover to PS cover and vice verse for the breather). I can't imagine that being an issue and creating the oil leak.

I have also seen products where you put an additive in the oil and it resolves main seal leaks. Blue Devil Rear Main Sealer. Bad idea? How does something like that work for the rear seal and not the front (since it isn't advertised for the front seal)?

blykins · #5 (**permalink**) 02-18-2023, 11:50 AM

It could be.

I'm not a fan of PCV valves. Never run them, don't suggest running them.

Maybe try a breather on both sides and see if the leak stops.

Otherwise, you can change that seal in under an hour.

twobjshelbys · #6 (**permalink**) 02-18-2023, 11:55 AM

Quote:

Originally Posted by SBSerpent

Could the leak be caused by crankcase pressure issues? I do have a PCV on one valve cover and a breather on the other so the crankcase is being vented. The only thing that I did (about 1000 miles ago) was to swap the locations of the PCV/breather (i.e. I moved the PCV from DS cover to PS cover and vice verse for the breather). I can't imagine that being an issue and creating the oil leak.

I have also seen products where you put an additive in the oil and it resolves main seal leaks. Blue Devil Rear Main Sealer. Bad idea? How does something like that work for the rear seal and not the front (since it isn't advertised for the front seal)?

The PCV and breather are not interchangeable. One side is intake, the other exhaust. So now you've got your intake side pulling air in backwards through the PCV (which is probably check-valved...)

SBSerpent · #7 (**permalink**) 02-18-2023, 04:18 PM

Quote:

Originally Posted by twobjshelbys

The PCV and breather are not interchangeable. One side is intake, the other exhaust. So now you've got your intake side pulling air in backwards through the PCV (which is probably check-valved...)

I've always wondered about this. I've seen 351W motors with the PCV on either side so I'm trying to understand why one side of the motor would be more appropriate than the other.

twobjshelbys · #8 (**permalink**) 02-18-2023, 06:58 PM

This basic is the reason that the "oil catchers" on the PCV side may collect small amounts of oil (that are insignificant (note 1, 2) ) and why the other side rarely has any in it (note 3)

Note 1: Oil catchers can gather more blow by in boosted applications which is why some blower manufacturers might include one in their kit. The legend is that this oil reduces octane and HP. The reality is that it amounts to a drop or two per tank full if that much and is in fact precisely what the PCV system is designed for.

Note 2: The presence of significant amounts of oil in the catcher under anything but redline track operation is not a solution - it is an indicator of a much bigger problem.

Note 3: Similar to #2: Some people insist on putting oil catchers on both sides. The fact is that the non-PCV side rarely shows any collection is because is is INTAKE (air flows in the vent). So, if you have oil coming out the intake side, you've got one big whoppin problem and are probably using oil measured in quarts per mile.

SBSerpent · #9 (**permalink**) 02-27-2023, 05:04 PM

I imagine that the seal is a standard replacement seal for a 351W. Anyone have a part number for the seal?

Sydney · #10 (**permalink**) 02-27-2023, 06:35 PM

I just did this job a couple of months ago. I used a Timken 2692. It appeared to be of better quality than the one that I removed.

Sydney

SBSerpent · #11 (**permalink**) 02-28-2023, 04:34 PM

The oil leak is a little confusing to me. A day after driving the car, I noticed an oil puddle on the garage floor directly under the harmonic balancer, about the size of a quarter. I wiped up the oil spot and noticed a film of oil on the oil pan flange at the location where the flange is curved to accommodate the crank. I wiped the oil pan flange to remove the film of oil and then placed a sheet of white paper on the garage floor to see if any more oil would leak. The next day, there was again a spot of oil, albeit somewhat less than the size of a quarter. A film of oil once again on the oil pan flange. Wiped the flange clean and moved the sheet of white paper over a bit to see if any more oil would leak. Lo and behold, the next day (3rd day of leaking oil) there was once again a spot of oil. A smaller amount than the previous 2 days but still there.

Here's where the confusion lies. I can understand the oil leak over the course of 24 hours after parking the car. The oil all flows down back into the pan after the motor is turned off and thus the leak. But after 24 hours, you would figure that all the oil is now in the pan. Why am I still seeing a leak appear 48 and 72 hours after I had parked the car? It's not like the front main seal has an oil reservoir behind it where it keeps leaking from (i.e. like a loose oil temp sensor that leaks oil due to the pressure of the standing oil in the oil pan).

Thoughts?

Sydney · #12 (**permalink**) 02-28-2023, 06:22 PM

I had similar experiences for years before i was convinced it was the seal. I'm guessing that the crankcase pressure shoots it out of the seal on the back of the balancer and the balancer slings it around all over the front of the engine. Most of it you can't see until you pull the balancer.

When I did this job a while back, most of the time spent was cleaning the front of the engine from all the grime that I couldn't see until the pulleys came off.

Sydney

BDR0572 · #13 (**permalink**) 03-28-2023, 03:07 PM

Quote:

Originally Posted by SBSerpent

This would be on a stroked 392 (351W block). Ford Racing Motor. Need to replace the front main seal. Can this seal be replaced from the front of the timing chain cover or does the cover need to be removed (replaced from the rear of the cover)?

This is the stock motor on a 2011 build.

Any other nuggets of information regarding the replacement would also be greatly appreciated.

Also inspect the balancer shaft for wear, they make a seal runner to go over the shank to fix it if damaged

hauss · #14 (**permalink**) 03-31-2023, 07:45 AM

Wait a minute, I have been reading post after post and I was told oil leaks on cobras, are normal. Are you guys saying their not anymore?

6t8stang · #15 (**permalink**) 04-03-2023, 11:50 AM

Quote:

Originally Posted by hauss

Wait a minute, I have been reading post after post and I was told oil leaks on cobras, are normal. Are you guys saying their not anymore?

You're confusing cobras with harleys....