Rear Main Seal Advice

jrstock · 05-27-2019, 08:08 PM

I have observed a leak from my rear main seal. The leak is occurring ,not at the seal split line, but at the bottom 6 o'clock position. Currently using a Fel Pro 2090 seal.

I've pulled the seal and it does not look worn or damaged.

Is there a way to shim between the seal to tighten the clearance to the crank? Is there a better SBC main seal to use?

Is there a tool to locate the 2pc rear main seal adaptor on the crank that I should be using?

Any other tricks to stop the leak?

Thanks in advance for the advice.

FED 387 · 05-27-2019, 09:02 PM

Put a thin film of rtv between the block and cap before installing the 2 halfs also rotate the seal splits about a 1/4 from horizontal and put a little dab there too--make sure the oil pan rail is FLAT so it's not pinching the seal and is making proper contact with the seal.maybe wipe a light film of oil on the seal to help on start up

ss3011 · 05-27-2019, 09:48 PM

What is the year of the block ? Is it a 2 pc or a 1 pc seal . Has the block been line honed ?

jrstock · 05-27-2019, 09:50 PM

The block is a late model bowtie block with an adaptor to run 2 piece seal. It has been line honed.

Alan Nyhus · 05-27-2019, 10:13 PM

One block I used had been line bored and the rear seal was leakage prone. Shortened the half of the seal that fits in the block until it fit normally. No offset and a dab of Valco aluminum silicone on the back of the seal and the parting lines.

We've seen a rash of rear main seal leaks lately with both the brown and blue seals.

SSDiv6 · 05-27-2019, 11:44 PM

Quote:

Originally Posted by jrstock

The block is a late model bowtie block with an adaptor to run 2 piece seal. It has been line honed.

I have seen this happen a few times with the Bowtie block using the adapter. If the block has been align bored or honed, I remove the locating dowel and use the Allstar Performance rear seal adapter alignment tool P/N ALL26127.

https://allstarperformance.com/align...pter-all26127/

carl hinkson · 05-28-2019, 07:12 AM

Quote:

Originally Posted by jrstock

I have observed a leak from my rear main seal. The leak is occurring ,not at the seal split line, but at the bottom 6 o'clock position. Currently using a Fel Pro 2090 seal.

I've pulled the seal and it does not look worn or damaged.

Is there a way to shim between the seal to tighten the clearance to the crank? Is there a better SBC main seal to use?

Is there a tool to locate the 2pc rear main seal adaptor on the crank that I should be using?

Any other tricks to stop the leak?

Thanks in advance for the advice.

2090 seal is not a good number

Nmbr1GMfan · 05-28-2019, 08:39 AM

My issue was the crankshaft wasn't perfect where the seal would normally ride, this seal fixed it. Fel-Pro BS 11829-1 Rubber 2 piece offset double lip seal

FED 387 · 05-28-2019, 10:39 AM

I think he means 2909

carl hinkson · 05-28-2019, 11:46 AM

Quote:

Originally Posted by SSDiv6

I have seen this happen a few times with the Bowtie block using the adapter. If the block has been align bored or honed, I remove the locating dowel and use the Allstar Performance rear seal adapter alignment tool P/N ALL26127.

https://allstarperformance.com/align...pter-all26127/

That does not work with a 400 main

05-27-2019, 08:08 PM	#1
jrstock Junior Member Join Date: Feb 2015 Posts: 16 Likes: 0 Liked 0 Times in 0 Posts	Rear Main Seal Advice I have observed a leak from my rear main seal. The leak is occurring ,not at the seal split line, but at the bottom 6 o'clock position. Currently using a Fel Pro 2090 seal. I've pulled the seal and it does not look worn or damaged. Is there a way to shim between the seal to tighten the clearance to the crank? Is there a better SBC main seal to use? Is there a tool to locate the 2pc rear main seal adaptor on the crank that I should be using? Any other tricks to stop the leak? Thanks in advance for the advice. Last edited by jrstock; 05-27-2019 at 08:13 PM.

05-27-2019, 09:02 PM	#2
FED 387 VIP Member Join Date: Jun 2006 Posts: 3,349 Likes: 325 Liked 280 Times in 150 Posts	Re: Rear Main Seal Advice Put a thin film of rtv between the block and cap before installing the 2 halfs also rotate the seal splits about a 1/4 from horizontal and put a little dab there too--make sure the oil pan rail is FLAT so it's not pinching the seal and is making proper contact with the seal.maybe wipe a light film of oil on the seal to help on start up

05-27-2019, 09:48 PM	#3
ss3011 Senior Member Join Date: Feb 2002 Location: Southeast Michigan Posts: 885 Likes: 63 Liked 221 Times in 102 Posts	Re: Rear Main Seal Advice What is the year of the block ? Is it a 2 pc or a 1 pc seal . Has the block been line honed ?

05-27-2019, 09:50 PM	#4
jrstock Junior Member Join Date: Feb 2015 Posts: 16 Likes: 0 Liked 0 Times in 0 Posts	Re: Rear Main Seal Advice The block is a late model bowtie block with an adaptor to run 2 piece seal. It has been line honed.

05-27-2019, 10:13 PM	#5
Alan Nyhus VIP Member Join Date: Dec 2002 Location: Lower Dakota territory Posts: 1,164 Likes: 1,013 Liked 761 Times in 225 Posts	Re: Rear Main Seal Advice One block I used had been line bored and the rear seal was leakage prone. Shortened the half of the seal that fits in the block until it fit normally. No offset and a dab of Valco aluminum silicone on the back of the seal and the parting lines. We've seen a rash of rear main seal leaks lately with both the brown and blue seals. __________________ "That'll never work....."

05-28-2019, 08:39 AM	#8
Nmbr1GMfan VIP Member Join Date: Aug 2013 Posts: 1,766 Likes: 1,197 Liked 1,957 Times in 492 Posts	Re: Rear Main Seal Advice My issue was the crankshaft wasn't perfect where the seal would normally ride, this seal fixed it. Fel-Pro BS 11829-1 Rubber 2 piece offset double lip seal __________________ Todd Greene

05-28-2019, 10:39 AM	#9
FED 387 VIP Member Join Date: Jun 2006 Posts: 3,349 Likes: 325 Liked 280 Times in 150 Posts	Re: Rear Main Seal Advice I think he means 2909