Who makes the best replacement real main seal for a 528 hemi? I'm hoping to never have to do this again so I want to get the right one the first time.

I’ve recently used the FelPro seal with blue side seals.

Nice kit.

Most of the time it’s the installation that causes the leak, not the seal.

Crank out, make sure the rear retainer is flat where it meets the block. Hand file the two mating surfaces until flat.
Use a light on inside of engine while viewing from rear of engine.

Lay the top seal in the block then the bottom in the retainer.

(Lay the crank in the block and make sure the rear seal lip touchs the crank seal journal).
(Remove the crank).

Install the retainer (mock up) and snug up the bolts then back off one half turn.
See if the retainer moves back and forth - if it does you have to align the lips of the top and bottom seal then snug up the retainer.

Once you have done that - scribe a line from the retainer to the block. This is your reference mark for final assembly.

Remove the seals and retainer - light coat of RTV (light) on back side of seal and install the seal in block.
Do the same thing for the bottom seal.

Install the crank, place a dab of RTV at the bottom of the block in the corner on each side - a light coating on both left and right side of the retainer ends, place the side seals in the retainer grooves so they stick out an 1/8” past the retainer ends. Slide the retainer in to the block - as you get close to being almost all the way in those side seals will become flush with the pan rail.

Align the retainer to that scribed reference point on the block done earlier.

Tighten up the bolts and let it set overnight before running engine.

I have never had a leaking seal using this procedure.

Make sure you don’t use a cracked retainer,

Ok thanks for the help, I appreciate it. It is possible to change the seals without moving the crankshaft, correct? The motor is still installed in the car and I was hoping to not have to pull it out if possible.

Yes, what normally works best is to have someone turn the crank as you rotate the seal out - turning them both at the same time and in the same direction.

Then do the reverse - turn the crank as you install the seal. Make sure to use a real thin shim between the block and the seal so you don’t shave any rubber off.

Once in follow the rest of what I mention, RTV in the corners, etc.

While I have never used the method - some people advocate pushing the seal in so one end is underflush of the block and then do the same on the retainer. This should make the lips align each other.

Ok, I'm finally in the middle of trying to install the new rear main seal kit. The two halves actually slide in very easy with the crank still in the motor and the mains are still tight, which kind of worries me. The other problem that I'm having is with the side seals. Is there any trick to get these to stay in? Every time I go to slide the retainer into the block it pushes the seals right out. I've tried using a high tack gasket sealer on them and letting them set up first to try and help hold them, but they still just push right out. Am I better off just eliminating them and using a gasket maker in their place?

lots of guys just fill up the side seal area with black[?] RTV.
i haven't done one for a while now, so take this advice for what you paid for it.

This job is always harder upside down but here’s is what I do.

I let the side seals stick past the retainer about an 1/8” and once the seals and retainer are started in the block I pinch the retainer and seals with my fingers and slowly slide the retainer down in to the block - the seals will stop once they hit the block - just keep pushing the retainer until it’s flush with the pan rail.

I finished installing the new rear main seal kit, followed all instructions from everywhere exactly, and the motor still has a terrible leak from the rear main. I'm at a loss at this point. Brand new motor in the car that isn't even drivable.

You did install the seal with the lip forward correct ?

correct. After about two or three minutes of the engine running, there is a steady drip of oil coming off the the rear main .

Which brand seal did you use this time?
I've had several defective seals that wouldn't touch crankshaft surface at all, no sign of contact from the seal lip on the crankshaft after removing the seal holder
I ended buying the newer more expensive ones made from a softer material and they will leave a mark in the grease I use to lube the crank seal area on the cranks, no leaks so far on two that I had to fix
The oil can leak from the side seals, the main seal or from under the cap to the block also To fix it properly you need to figure out exactly where it is leaking first
Good luck, let us know what you find out to fix it , that will help others on here later

I used the fel-pro viton seal kit. What concerned me originally, was how easy the old seal came out and how easy the new seal went in. The crank was still in the motor and all of the main caps were tight. I was able to grab the old seal and pull it out fairly easily without even having somebody rotate the crank. I put rtv on the back side of the seal and oil on the crankshaft side and I was able to push the new one right in by hand. It also bothers me that a brand new motor with 100 miles on it is already on its second seal and they both leak. Hopefully there isn't something defective with the motor that's not allowing it to seal up. The block is a world aluminum model. I can't find any info on it or if it requires a different seal that a stock hemi version, but I compared the original seal that came out of it with the new fel-pro one that I bought and they were the same.

Is there any chance that this could be caused by too high oil pressure or crankcase pressure issues? I had all of my gauges recalibrated ( still unsure of how accurate they are), but when the engine is running at idle, the oil pressure gauge is all the way into the H and when it warms up, it is just touching the H at idle. I haven't been able to drive it since I hooked it up to see where it's at with higher RPM's. The engine builder told me to run no less than 20w/50 oil, so I know that is definitely contributing to the high oil pressure. The parts list for the engine said it has a high volume oil pump, but maybe they put a high pressure in it instead. I have the Milodon billet posi-lock breathers on it, with one of the breathers running to the vacuum port on the one carburetor and the other venting to the open air. Is there a way to measure for too much crankcase pressure? I just find it funny that a brand new motor, from who many consider the top hemi guy, leaked from day one and then I put another new seal kit in and it still leaks terribly.

Silly question

Are you absolutely sure the leak is from the rear main and not a galley or cam plug ? Had a customer several years back in a similar situation. he had done 4 or 5 pan gaskets, a new pan, and 3 rear main seals.
He brought it in to us totally frustrated.
It turned out to be the LR block plug (galley access) was loose and dripping down making him think it was the rear main.
We thoroughly brake cleaned the back of the block through the inspection cover, let it dry, fired the motor up and within a short period the leak appeared. We shut the motor off. Using a pair of mechanical fingers with a small paper towel I snaked it up into the bell housing staying away from the rear main. When we removed it it was wet with oil. HMMM, Oil doesn't run uphill
We dropped the trans, sealed and tightened the plug and it has never leaked a drop since. (12 years ago)

Keep us posted

I knew a guy too that thought his rear main seal was leaking but was a galley plug

If I look behind the flywheel I can see two larger plugs on the right and left side of the rear of the block and there is another smaller one that is slightly offest to the right, and those three are not leaking. Are there any other plugs that aren't visible with the flywheel installed? If I watch from underneath the car with the engine running, once it warms up, I can see oil dripping from the bottom center of the lower crankshaft seal. Then the oil is slung over the entire bottom of the car, all over my headers, rotors, tires and all the way back to the rear axle. I will try to look up behind the flywheel with a small mirror to look for any other possible leaking plugs, but the ones that are visible are dry.

Me to, a friend of mine went through that after the engine dyno operator forgot to tighten up the oil galley plug that he had removed to use a oil pressure fitting in that hole for the dyno testing

I am not 100% sure about the location of other plugs. Maybe some one else will chime in. But the cam plug is directly above the crank and is also a possibility Kind of a long shot but maybe not .

I am ASSUMING at this point that you have absolutely verified that the back of the intake, oil pressure ports and valve covers are all 100% dry.

Keep us posted

Yes, the back of the intake, both oil pressure ports and both valve covers are dry and don't have any leaks. I bought a uv oil dye kit that I will try next to help pinpoint the leak after I check the back of the block one more time.

Probably already checked but most of the aftermarket oil pan bolts are a touch longer than factory and will bottom out and not compress the gasket. Found this out my hemi. I thought it was rear main also. My easy solution was to add 1 grade 8 flat washer to each bolt.