Hemi rear main seal replacement

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.

My block has studs for the oil pan, so my pans tightened right up against the block. Thanks for the heads up though.

Does your motor have main studs also?
If so look at the rear of the oil pan and the oil pan gasket under the rear main seal and see if the #5 main studs are touching them
If so you may have found your oil leak before removing the rear main seal holder again

My son just built a 383, we combined the rope seal kit with the blue side seal kit and so far, really good.

does your crank have the knurling in the seal area to accommodate the rope seal?

Yes, the motor does have main studs. Do you mean check to see if the studs are hitting the oil pan itself or the rear main seal retainer?

The crank doesn't have any knurling.

https://board.moparts.org/ubbthreads/ubbthreads.php/topics/1856815/1.html


Install seal 6 and 12, fill sides with rtv not using the gaskets

Check the oil pan for contact

I've got the motor torn back apart again. There are no contact marks on the oil pan. There are very slight signs of contact from the nuts on the main cap touching the windage tray. The replacement oil pan gaskets that I installed are slightly thicker, so there isn't anymore interference. The problem that I'm having now is trying to get the upper half of the rear main seal out from the block. I think it's from the rtv on the back of it holding it in. Are there any tips on getting this out without it breaking or ruining anything with the block or crank. I'm afraid of it tearing and still being stuck in there and then I'll be screwed.

You will need to push the top of the seal out with self made tool (heat and bend a thin cheap screwdriver, cut or grind the head off it and polish it up) or similar
while turning the crankshaft at the same time in the same direction you're pushing it.

One you get the top part of the seal out, how will you clean all that nasty rtv out of the seal groove, though?

For many years I've read the advice here to use rtv and other products on the back side of the dynamic seal (dynamic meaning the part the crankshaft rotates against),
I feel it is not needed and disagree.

RTV as a substitute for the side seals is okay. The old white asbestos side seals have always worked fine for me but I usually injected rtv after they
were installed. And since they stopped making them, it's been straight rtv after that.

they sell a seal puller kit that may work for you. Its cheap enough.

https://www.summitracing.com/parts/...I5MXY4wIVD77ACh0H5gZwEAQYBSABEgKxnPD_BwE

All the seal pullers I have seen are for rope seals. Has a screw type deal on the end.
The lip seal has a metal core I think so I don’t think you can screw in to it.

I might be wrong on this.

I always get raked over the coals for suggesting to loosen the rear main to get the upper seal out but if you do this the seal comes right out with no turning of the crank.

With an auto trans - remove the converter bolts and push the converter back to disengage it from the crank.

Then loosen up the main caps - more at the rear and less at the front of the engine.

That may make things easier for you.

What I would do then is remove each cap one at a time and make sure the bearing shell tang is in place then install that cap and tighten.
Since you are turning the crank you don’t want to take a change that a shell rotated out of alignment.

The car is a 4 speed. I'm going to try a windshield seal install tool first before loosening anything first. The problem is the rtv that's holding it in. When I took the original seal out, I was able to pull it out easily without loosening anything or even turning the crank. This is what worries me that something is machined wrong and the motor will always leak.

[s][/s]

Well, I got everything back together on the motor and I ended up installing the seal at the 12 and 6 o'clock positions. I started the car up and let it idle for probably about 15 minutes without a drop of oil coming out. However, as soon as I sat in the car and gave it some gas, it started leaking like a sieve again. Let off of the gas, and it will continue to idle without leaking. I just don't get it. I at least have it where it will idle at operating temperatures without leaking, but still has a terrible leak under even slight throttle. It's looking like another summer with no driving time at all at this point.

Which way is the upper sealing edge of the seal pointing, towards the front or rear of the engine?

Towards the front.

Are there any ideas as to what would cause the leak only to happen while the motor is being reved? If the seal was damaged and or installed incorrectly, shouldn't it leak at all times? Is it possible that it's a crankcase pressure issue that is building up pressure during higher rpm's?

It sounds like to me that it isn't the main seal leaking, it might be the oil pan gasket or maybe even the side seals on the main seal holder leaking when the revs go up
If it is the side seals or a pan gasket it won't leak oil onto the engine side of the flywheel, it will leak down around and over the edge of the oil pan instead
Take your time with car up on jack stands and have someone run the throttle while you look at the oil leak to see if you can make sure EXACTLY where it Is leaking from Good luck

Leaking head gasket might do it - might as well check & compare cylinder compression

Is the retainer a stock one or is it a CNC aftermarket? If its a CNC one check that it doesn't hit the main cap as in photo. May need to add clearance there.

I had had to redo same on my 440. My suggestion is to install retainer without side seals. Retainer channel in the block must be cleaned of any oil residue. Without side seals lets the retainer find its neutral position in relation to the seal so in other words the seal is aligning the retainer front to back position. Then Fill the side seals with RTV. But you may say "how to do that with engine in car and clutch in place. Use a 10ml Syringe with a small gauge luer lock blunt needle or a meat marinade injector needle. Don't use the big marinade syringe, keep with the 5ml or 10ml size one. You can get these items from amazon.

https://www.amazon.com/gp/product/B07L2TXW1C/ref=ox_sc_saved_title_6?smid=A1IYIADSPFVZEE&psc=1

My picture in prior post you can see the gray RTV filling the gap between block and retainer.

Also, I used lock-tight 518 on the 2 ends of the main seal and put it at 12 and 6 oclock.

I believe that it is a cnc aftermarket retainer. The car has a world aluminum block and thats what came with the motor when I bought it. I didn't use any side seals, just rtv in the channels.