Rear main seal lesson

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pentastarpro

pentastarpro

speed trials
Joined
Oct 25, 2009
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Location
Apple Valley,CA
Never had a problem with rear main seal leaks until new 512ci stroker build. Everything went per "text book" during break-in except minor but anoying oil leaks. Cometics valve cover gaskets solved half the problem but two tries at rear seal area didn't help.
Finally decided to bite the bullet, put it back on engine stand and start disassembly.
Low & behold, a slight too much Ultra Black behind the seal in cap came out & fouled the seal area. (see pic)
100_2911.JPG

As they say, a little is good but a lot isn't always better.
 
I only use a small dab on the seal ends where the 2 halves meet. 65'
 
I never use any goop down there. Bare seal halves
Just 4 pea sized dabs of Right stuff where the pan gaskets join, dozens and dozens of engines.
No drama.
 
Glad you nailed that.
My fresh 383 build has leaked since day one. Also chased and stopped valve cover leaks, but the rear main continued to leak.
Recently had the rear main changed to the Vitton, with the engine in the car. Still leaked.
Tried again with the billett cap and new Vitton, still leaks.
 
Joey4speed said:
Glad you nailed that.
My fresh 383 build has leaked since day one. Also chased and stopped valve cover leaks, but the rear main continued to leak.
Recently had the rear main changed to the Vitton, with the engine in the car. Still leaked.
Tried again with the billett cap and new Vitton, still leaks.
Click to expand...
It is real easy when working with the engine in the car to put the seal in backwards. I’ve done it.
 
Tks for your replies guys.
As I said, many engines built over the yrs with both rope & rubber seals without problems. As ply65 said I usually only put a small dab on ends of seal but must have been overindulging that nite or simply distracted to put that much sealant in there.
At least it doesn't appear I have to pull the crank to get it back together.
Right, no drama here. just need to pay attention. Hi Hi
BTW, real happy with 1150cfm Dominator through Holley Refurbish program. Dyno test yet to be run.
 
I always use a small amount of silicon on the seal halves. I use a cartridge gun with a small nozzle so that I can control the amount of silicon. I never use the small tubes of silicon because I find it difficult to control the amount of sil deposited.

I also leave out the side seals & just use silicon. These can get displaced during installation & be a future leak source. Never had a problem doing this.
 
I put a small dab on the end of each seal half and then run a small bead where the seal retainer meets the block. On engines where the seal installs into the rear cap, I do the same, but run a small bead along the block surface to where the machined ledge is next to the ends of the oil pan gasket. This effectively seals the seal ends along with the entire joint where the main cap meets the block. Been doin it that way over forty years and never had a leak on a newly assembled engine. So far.
 
Good info above this post. I'll add that I clock the seal haves by maybe an 1/8" so the seal halves do not line up exactly with the cap parting line.

I also clean the metal surfaces thoroughly with brake cleaner prior to massaging the sealant into the metal to insure good adhesion between the sealant and the metal surface.

I also use a small bead of sealant along the sides of the seal retainer and block parting lines on the outside of the two parts.

On a somewhat related issue, make sure to use the correct length oil pan bolts in the seal retainer, they are shallower, as they are not drilled and tapped as deep as the rest of the oil pan bolt holes on the block. A buddy found this out the hard way when trying to chase down what he though was a rear main leak.
 
jbc426 said:
Good info above this post. I'll add that I clock the seal haves by maybe an 1/8" so the seal halves do not line up exactly with the cap parting line.

I also clean the metal surfaces thoroughly with brake cleaner prior to massaging the sealant into the metal to insure good adhesion between the sealant and the metal surface.

I also use a small bead of sealant along the sides of the seal retainer and block parting lines on the outside of the two parts.

On a somewhat related issue, make sure to use the correct length oil pan bolts in the seal retainer, they are shallower, as they are not drilled and tapped as deep as the rest of the oil pan bolt holes on the block. A buddy found this out the hard way when trying to chase down what he though was a rear main leak.
Click to expand...
I have for many years ran a bead of RTV after the seal retainer is installed on the outside. I have a few seal retainers with the bottoms knocked out from someone using to long of bolts. You can still save from having to replace it. If you clean the hole good with brake Kleen and the bolt and install it with RTV on the bolt.
 
Joey4speed said:
Glad you nailed that.
My fresh 383 build has leaked since day one. Also chased and stopped valve cover leaks, but the rear main continued to leak.
Recently had the rear main changed to the Vitton, with the engine in the car. Still leaked.
Tried again with the billett cap and new Vitton, still leaks.
Click to expand...

put u some vacuum in the crankcase , it will help !
 
jbc426 said:
On a somewhat related issue, make sure to use the correct length oil pan bolts in the seal retainer, they are shallower, as they are not drilled and tapped as deep as the rest of the oil pan bolt holes on the block. A buddy found this out the hard way when trying to chase down what he though was a rear main leak.
Click to expand...
Well ****. Looks like I'm about to pull all my oil pan bolts and have a look-see. I never knew this, and I've been trying to hunt down an oil leak.
 
Righty Tighty said:
Well ****. Looks like I'm about to pull all my oil pan bolts and have a look-see. I never knew this, and I've been trying to hunt down an oil leak.
Click to expand...

You only really need to check the 2 bolts that go into the rear seal retaining bulkhead. Pull them and use a small wire to check and compare the depth of the holes vs the length of the bolts.

Also, we both started using oil pan rail reinforcing plates as part of an effort to avoid distorting the pan rail. I sourced mine from Hughes Engines, while my buddy made his. It virtually eliminated the dimpling that pan bolts can cause in the pan rail, especially when using 2 gaskets and a windage tray.

Hughes Engines
 
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