Rear main seal 5.7

[78 Thompson]

I recently installed a rebuilt engine, a 96 mercruiser 5.7
I installed a Felpro rear seal,
after reading more threads on rear seals, it sounds like maybe I wasn't suppose to put oil on the seal, so it appears to be leaking after running engine for a couple hours. I also had a hard time getting the seal in, over the crank, with the engine on the stand, so I could have possibly damaged the seal getting it over the crank. Another thing I've seen is an installation sleeve, to make install easier, I'm guessing I should have had one of them?
I am in the process of pulling engine back out, to most likely change the rear seal again, one of my questions is should I buy an OEM seal, looks like they are around $100 or go with the Felpro again $25
Is the OEM really that much better, that its $75 more? The part numbers are kinda confusing for the OEM, the original is 26-14240, If I'm not mistaken the new number is 26-8M0077606? Seems like the dealers don"t really know what the part number is either. lol
So do I oil seal or not, with Felpro or OEM? where do I get the sleeve?
Any help with this will be greatly appreciated,
Thank You

 

[78 Thompson]

I recently installed a rebuilt engine, a 96 mercruiser 5.7
I installed a Felpro rear seal,
after reading more threads on rear seals, it sounds like maybe I wasn't suppose to put oil on the seal, so it appears to be leaking after running engine for a couple hours. I also had a hard time getting the seal in, over the crank, with the engine on the stand, so I could have possibly damaged the seal getting it over the crank. Another thing I've seen is an installation sleeve, to make install easier, I'm guessing I should have had one of them?
I am in the process of pulling engine back out, to most likely change the rear seal again, one of my questions is should I buy an OEM seal, looks like they are around $100 or go with the Felpro again $25
Is the OEM really that much better, that its $75 more? The part numbers are kinda confusing for the OEM, the original is 26-14240, If I'm not mistaken the new number is 26-8M0077606? Seems like the dealers don"t really know what the part number is either. lol
So do I oil seal or not, with Felpro or OEM? where do I get the sleeve?
Any help with this will be greatly appreciated,
Thank You

This is my serial number OK012416

 

[kd4pbs]

Felpro is every bit as good as OEM. The lip is supposed to be oiled. The seal housing needs a gasket, and a bit of RTV should be put on the cap parting line. I usually dab a thin coat on non-hardening sealant (permatex no. 2) on the seal outer surface where it goes into the holder as well as the holder gasket. I have never used a sleeve to install but carefully ensure the lips are where they should be while installing and never had one leak.
Did you put sealant in the crotches where the oil pan seal contacts the corner between rear main cap and block?

 

[78 Thompson]

Felpro is every bit as good as OEM. The lip is supposed to be oiled. The seal housing needs a gasket, and a bit of RTV should be put on the cap parting line. I usually dab a thin coat on non-hardening sealant (permatex no. 2) on the seal outer surface where it goes into the holder as well as the holder gasket. I have never used a sleeve to install but carefully ensure the lips are where they should be while installing and never had one leak.
Did you put sealant in the crotches where the oil pan seal contacts the corner between rear main cap and block?

I'm pretty sure I put sealant in them crotches, I went by the book, the Mercruiser manual, so if it said to do it, I did it. I did have a hell of a time getting my fingers in there because of the stand, so on 1st attempt the seal folded over. I guess I should have just bought a new seal at that point, and took the engine off the stand.

 

[kd4pbs]

Yeah… the oil seal is lots easier if you do it after taking off the stand but before bolting on the flywheel. I put the seal housing on while on the stand but wait to install the seal. Ye olde 2-piece seals definitely held the advantage here.

 

[Scott Danforth]

if you lost the spring on the seal, it will leak. did you use the installing cup?

the part number

s26-8M0077606?

is a mercruiser number. that is NOT the engine OEM, however the engine marinizer. so you are paying for a $20 seal, that they put in an $2 box with a mercruiser part number to sell you for $100

OEM seal from GM is $33 https://www.rockauto.com/en/moreinfo.php?pk=7223932&cc=1303366&pt=5604&jsn=949 or $29 from Bezos's mega warehouse. https://www.amazon.com/GM-Genuine-Parts-12554314-Crankshaft/dp/B09CVYV71M/

Felpro is $22 and comes with an extra gasket when you pull the adapter off as well as the installing cup. https://www.rockauto.com/en/moreinfo.php?pk=447422&cc=1303366&pt=5604&jsn=945

 

[78 Thompson]

if you lost the spring on the seal, it will leak. did you use the installing cup?

the part number

is a mercruiser number. that is NOT the engine OEM, however the engine marinizer. so you are paying for a $20 seal, that they put in an $2 box with a mercruiser part number to sell you for $100

OEM seal from GM is $33 https://www.rockauto.com/en/moreinfo.php?pk=7223932&cc=1303366&pt=5604&jsn=949 or $29 from Bezos's mega warehouse. https://www.amazon.com/GM-Genuine-Parts-12554314-Crankshaft/dp/B09CVYV71M/

Felpro is $22 and comes with an extra gasket when you pull the adapter off as well as the installing cup. https://www.rockauto.com/en/moreinfo.php?pk=447422&cc=1303366&pt=5604&jsn=945

I bought a Felpro gasket set and it didn’t come with that install sleeve, I’m thinking this wasn’t the PTFE seal. So the Felpro Bs40656 is supposed to be installed dry right, are these as good as GM?
Is the GM 12554314 the same material, PTFE, it says Teflon? Do I install the GM dry?
I don’t know if I understood about, it’s not the OEM seal, do you mean it was a GM part, not a Merc part? Not that I want to pay for Merc mark up, just wasn’t sure if that’s what you meant.
Thanks for the great info

 

[Scott06]

I don’t know if I understood about, it’s not the OEM seal, do you mean it was a GM part, not a Merc part? Not that I want to pay for Merc mark up, just wasn’t sure if that’s what you meant.
Thanks for the great info

GM supplied the base engine to Mercruiser (tinned longblock), so the rear main seal is not made by mercruiser its made by GM (or for GM by a parts supplier).

Felpro is generally considered high quality stuff. Most likely it go buggered going around the engine stand. When you get the engine back out put it on a cradle or pallet and you can run it on the ground after the seal is replaced.

the flywheel cover has feet on it and you can build up 2x wood for the side engine mounts. Hook a garden hose to the water supply hose up from drive, fuel line in a gallon jug, hook a battery up and you can hot wire it at the cannon plug with two short wires.

 

[78 Thompson]

if you lost the spring on the seal, it will leak. did you use the installing cup?

the part number

is a mercruiser number. that is NOT the engine OEM, however the engine marinizer. so you are paying for a $20 seal, that they put in an $2 box with a mercruiser part number to sell you for $100

OEM seal from GM is $33 https://www.rockauto.com/en/moreinfo.php?pk=7223932&cc=1303366&pt=5604&jsn=949 or $29 from Bezos's mega warehouse. https://www.amazon.com/GM-Genuine-Parts-12554314-Crankshaft/dp/B09CVYV71M/

Felpro is $22 and comes with an extra gasket when you pull the adapter off as well as the installing cup. https://www.rockauto.com/en/moreinfo.php?pk=447422&cc=1303366&pt=5604&jsn=945

Just for future reference, how did you find the GM part number? Is there a site to search that or do you search a certain year Chevy car or truck?

 

[Scott Danforth]

Just for future reference, how did you find the GM part number? Is there a site to search that or do you search a certain year Chevy car or truck?

Rock Auto or GM parts direct are my two go-tos. the motor that mercruiser used is basically a truck motor with different head gaskets and induction. so I looked up a 1996-2000 Chev truck. (NEVER a car).

 

[78 Thompson]

Rock Auto or GM parts direct are my two go-tos. the motor that mercruiser used is basically a truck motor with different head gaskets and induction. so I looked up a 1996-2000 Chev truck. (NEVER a car).

I’m getting some confusing information searching for this seal.
When I search 96 Chevy k1500 , I get GM 10088158 which has an ID. Of 3.78 inch and thickness of .510
the 12554314 has an ID. of 3.58 and thickness of 1.18
Is this something to do with the Vortec change over, my engine isn’t a vortec, I guess I don’t know if the rear seal changed on the Vortec engine?

 

[Scott Danforth]

1996 was a cross over year for heads and block, however the 1-piece RMS was around since 1986

 

[78 Thompson]

1996 was a cross over year for heads and block, however the 1-piece RMS was around since 1986

Felpro has a different number too, Bs40626 looks like for 95 and older maybe.
Guess I will have to contact Felpro see if I can get this figured out.
Holy crap who knows if I even put the right seal on to begin with. Lol

 

[kd4pbs]

As far as I knew, the one piece seal is the same size between all of the small blocks, including the LT1/LT4. Now I’m going to have to measure the crank I have that came from the donor block I used.

 

[Grub54891]

When you get the old seal out be sure to check if the spring got left behind.

 

[78 Thompson]

As far as I knew, the one piece seal is the same size between all of the small blocks, including the LT1/LT4. Now I’m going to have to measure the crank I have that came from the donor block I used.

So I talked to Fel-Pro and he said the correct one was BS-40520, standard nitrile and the BS40626 is the correct PTFE, for I believe 1986-1995, I ended up getting the GM 10088158 which is a FluoroElastomer not the PTFE, I wasn’t quite sold on that PTFE stuff. Lol
Apparently in 1996 or later the crankshaft diameter is different, I was seeing that it’s smaller diameter, so that seal is BS40656, and I believe the GM 12554314 is the equivalent.

 

[Scott Danforth]

PTFE is Polytetrafluoroethylene which is a fluoro elastomer

 

[78 Thompson]

PTFE is Polytetrafluoroethylene which is a fluoro elastomer

My understanding by googling it, is that they are not the same. Fluoroelastomer is synthetic rubber, like Viton.
PTFE is Teflon, I don't know if its just a coating or what, but you are not supposed to use grease on the seal lips.
The GM seal has dabs of Grease all around the inside of the seal from the factory.

 

[78 Thompson]

Not trying to be a smart Azz, but this is the article I was looking at, I'm no scientist, so maybe I'm misunderstanding it. check it out pretty good info.

Fluoroelastomer (FKM) rubber is a thermoset elastomer while Polytetrafluoroethylene (PTFE) is a thermoplastic. Both are fluorinated materials comprising of carbon atoms surrounded by fluorine atoms, which gives them incredible chemical resistance. In this article, TRP Polymer Solutions pitches both materials against each other in an FKM vs PTFE comparison to see which is the ultimate fluorinated material.