Best Rear Main Seal Type

I have had (what I think) are chronic issues with the rear main seal on my 500 stroker. Crank is a 440soruce 400>>500ci 4.15 stroke. I have had leaks with:

- stock retainer + regular rubber seal (2 different seals)
- 440 source billet retainer + viton seal (currently installed)

I am going to try and pull the oil pan in the coming weeks and inspect the seal to confirm. In the meantime, I feel like I should go ahead an get a new seal so I am ready if it does appear to be leaky when I pull the pan.

I see 440source has two seals (above the standard rubber) - the Viton seal and the old school rope seal: here

With my history in mind, should I do another go round with the Viton seal or try the rope seal? Before anybody asks, I did ensure the two seal halves were not lined up with the retainer/block joint and used a dab of RTV around each joint of the retainer/block.

Also, I purchased the windage tray that has the silicone seals integrated from Summit. Any experience with these? Seems like such a great alternative to the PITA gasket sandwich.

Any help is greatly appreciated! Thanks!

Have you verified that it is the main seal leaking and not the side seals leaking? If not do that first before trying again. If it is the main seal it will leak out onto the crankshaft flange and the oil will be slung out onto the flex plate and outwards from their If it is leaking out of the side seals it won't be on the crank flange
I haven't had a rear seal leak in a lot of years, 100s of BB built.
Let us know what you find out, maybe I can help you stop this

Hey cab, Did you put any oil in them ??? LMAO Sorry couldn't resist

Agree here. It’s not the type of seal or the caps fault, it’s how you install it.

that likely won't seal properly on a stock style pan rail due to the stiffening beads. Mr gasket says its made for a flat pan rail. See their note below.


Pics below show the problem

Yep, leaked with our dimpled pan.
I was sure excited about the idea though.....

What brand pan is that??
I like the baffling.

Joe

My pan is a Moroso and it has flat rails (no beads). I am assuming you would use no RTV on this tray save for a dab at any joints?



I am open to any tips on installation. Which orientation to install, where to use RTV, etc.

Milodon

I had (thought I did) same issue on my 1st Gen 392 Hemi. Replaced rear main seal several times. Still had "the" leak. Finally found out rear of valve cover leaking, not the rear main seal. Just something else to check out.

there is also the rear cam soft plug. that is somewhat uncommon, but it bit me one time long ago. i can't remember what engine it was though.

Please confirm this is the correct orientation for the crank seal and side seals.

Looks good to me.
Seal the sides up after it is installed correctly and make sure the bottom seals slide all the way in to the touch the block on the bottoms of both of them before sealing the sides up
Let us know how that works out

Look leaky?

While I am having a little bit of a problem figuring out exactly what I am seeing there it kinda looks like the crank has knurling?

It was pretty much the standard for the factory to knurl the seal surface on the cranks back in the day, BUT they ran rope seals.

If that is a knurl you need a rope seal. The lip seal needs a flat surface.

Most old used cranks have the knurling worn down by the time we get to them so if the surface is smooth where the seal rides, then a lip seal is OK.

At least that has been my experience

Never heard this before. True or not?

Had a customer several years back that had changed the rear main, pan gasket and even the oil pan several times. first question I asked was who put the oil galley plugs in. He said he hid and SWORE the were sealed and tight. OK.
We proceeded to do the rear main and pan gasket 1 more time. Still leaking. After thoroughly brake cleaning the back of the motor and letting it dry, we started it and let it run for several minutes. We shout it off and using mechanical fingers with a small paper tower wadded up, I carefully snuck it up in bellhousing avoiding the bottom and rear main area.
When I removed we had oil. I said oil does not run uphill. We pulled the trans and flywheel while he watched. The RR galley plug was only finger tight with no sealant.
he left a pan gasket here so i had a sign maker buddy mount the gasket with "THINK OUTSIDE THE PAN JON" LOL

Poor guy he said his driveway looked like the EXXON Vladez had been docked there LMAO

My cam plug looks dry. Can anyone confirm that the crank knurling requires a rope seal? It would seem 440source would note that on thoer website since they sell so many cranks..

I don't believe that's true. All the BB cranks that I've seen have the knurling. The knurling helps keep the oil from getting past the seal as long as the knurling was done properly and not backwards, where it would direct the oil past the seal.

There are 2 ways to knurl a sealing surface. Crosshatch and diagonal. Some new cranks use a diagonal pattern that is supposed to draw the oil away from the seal while it is rotating. This is not a problem with PTFE seals that actually seal fine in a dry or low lubricant environment. This is why many new engine have their seals installed dry.

The crosshatch pattern mopar used back in the old days would draw oil to and away at the same time. Worked good for the rope seal and it's wide surface area, but lip seals slide across the grooves letting the oil pass by underneath.

Your crank looks like a diagonal pattern.

I went a round on a GM that had the seal replaced and it still leaked before I got a hold of it. I read more than any human should about seals when it came my way and the one thing I learned is there is a lot of debate on sealing technology. That's when I discovered some seals are installed dry.

Any idea on who made the crank? What are their opinions? Is the current seal a PTFE or traditional seal?

I am open to differing opinions. I hate rear main leaks and love to hear what works for others.

To clear some technical confusion, the purpose of any rubber seal having helix grooves is to physically throw the oil back in towards the engine... if the seal is installed reverse (with the grooves facing the transmission, it will physically pump oil out of the engine.

It make no difference if the crankshaft has knurls or not... they are there to keep a small amount of oil on the shaft where the seal makes contact.

Rope seals were simple, back in the day, to install and low cost to manufacture... as well as the casting grooves for the seals were not dimensionally held at tight tolerances... where as rubber seals more commonly need a tight fit into their retaining grooves.

I'm a former gasket engineer from a major company... these are common questions being asked.

Thanks for the clarification. I had a feeling the rope seal statement needed fact checking.

I know this subject is beat to death on here but I have found so much conflicting information, I am beginning to feel like I know absolutely nothing.

One last thing - good idea to cut the retainer down .010 or not? I know that will create a bit more "squish" on the seal but will the non-concentricity become an issue?

This post has some good info in it:
https://board.moparts.org/ubbthread...r-main-seal-replacement.html#Post2686329

You mentioned you had both OEM and Billet retainers to choose from. If you use the billet one, watch that it has proper clearance so it wont hit the cap as in the post above. I had one that would hit.Ordered a different one and it was fine.
When I re-did my rear seal, I did not use side seals and instead filled them with RTV. This worked out for my situation - no leaks. I was doing the job with the engine in the car and with trans attached. I mention this because if the engine is on a stand and your doing it there, I think you can see if the side seals are sliding in correctly and bottoming out. Plus you can then seal the sides again from outside because trans is not there. But while engine is in the car, you loose that ability.

and Thank you sir, I get tired of trying to help and usually being ignored.

http://www.hughesengines.com/Upload...al_Installation_InstructionsJune2006.pdf
This may help.

CJ -- DO NOT cut the retainer.. it will cause excessive pressure against the seal halves and premature wear.

Regarding the side seals, IF you only inject RTV silicone into those side vertical grooves, you need to add some kind of small wet (watered) felt strip into the side grooves.. because RTV .. with that type of thickness.. must have humidity to fully cure.

Otherwise, using the fiber strips often found in seal kits simply requires the strips to be pre-soaked in mineral spirits so that it will properly swell into the side groove.

Pre-molded rubber side strips may not fill the variable side seal gaps... the gaps vary per various production builds.

That looks right. Getting those side seals all the way down is the hard part. I leave the side seals longer than the cap and work the cap up-and-down so they sit all the way down in the block.
Also use a smear (not much) rtv between block and retainer ends. Make sure crank/seal have lube so the seal does not tear on startup.

That Summit windage tray looks a bit different than the Jegs version? The Jegs version has slips on the side, and that Summit version looks like it has holes?
I used the Jegs version of the windage tray on my 4.25" stroke 440 using an old Mopar Performance Street Hemi oil pan (and the viton rear seal like in the photo), and it sealed great!
Really happy with the results. no drips at all.

On the other hand, the 4.15" stroke low deck stroker was built with the standard rubber rear seal, and sandwitched factory type windage tray, and it is leaking pretty bad, but the milodon oil pan has taken some damage too.
Fixing that oil leak is just another project to get done. I already bought a replacement oil pan, and the Jegs molded windage tray.

Thanks for the feedback

Did you use any RTV or any other type of sealant on the tray/pan? I am picturing a dab of RTV on the joints between the block and retainer/timing cover? Anything else or just install "virgin"?

on the molded windage tray sealing, the seal material will stick to RTV,
If you are going to run the engine on a break-in stand or dyno, I would try installing the tray/gasket dry and then check for leaks. Tray and crankshaft seals.
You can RTV the gasket and depending on the oil pan rail, you might have to, it just makes the tray gasket material like a one-time use.
Once you use RTV with the tray, you will have to use rtv everytime you have the tray and oil pan apart.
Not really an issue if the crank seals (front and rear main) and you don't plan to take the engine apart again for a long time.

It is a good question. I had a 505" stroker that a friend and I build with his kid. Somehow, a piston was installed without the compression rings.
We had put some rtv at the timing chain cover and rear main seal retainer, so that is when I noticed how the rtv bonds with the trays gasket bead material, when going back into the engine.
I need to keep reminding myself to not get distracted when assembling engines, and double check what other people are doing if they are helping.
FWIW, I was filing the rings at the time, not installing the pistons.

I got the rear main, tray, and oil pan put back together around two weeks ago. Here is what I ended up doing:

- offset the two seal halves by 1/16" from the block, glued together with Lock-Tite 518 (Hughes's instructions mentioned this)
- two seal halves were slathered in bearing assembly lube (like maple syrup)
- very light black RTV where the retainer sits on the block (around bolts) and the retainer/block joint for the oil pan
- very light dab of black RTV on each block/timing cover joint
- tray and pan went on dry besides that

I was very positive about this as I went through 5-6 heat cycles and around 2 hours of run time with not a drop of oil. However, I took the Charger for a drive this morning and it was quite cold - right around freezing. When I got home and took a peek, I saw the dreaded drip on the bell housing.

I pulled the inspection cover and looked at it with the borescope. The crank knurling looks every so slightly "wet" like the most minor of leaks. I am wondering if this had anything to do with the super cold drive...

Anyways, I think I am going to put half a container of the Bars Rear Main Seal treatment as an insurance policy. I'm pretty sure I did this "right" or as right as I am going to get it. My oil filter (second new one) is slightly weepy as well (like one drop per drive) so hoping this will seal up these tiny little leaks.