Rear main seal

[Tazman100]

I just replaced my rear main seal while I was swapping the transmission a couple months ago but it appears to be leaking already. Is there anything else that could leak that might look like a rear main leak? I can definitely see a stream of oil comin down behind the flex plate. I'm pretty sure I got a good look at the oil pressure sensor and it doesn't appear to be leaking. Kinda really annoyed about this. Was a Felpro seal set with cover gasket and I followed the instructions. 2005 GMC Yukon 5.3L

Hi, just saw a video about a small (maybe) block off plate near the starter that leaks at times and looks like the rear seal.

 

[West 1]

The only thing close to the starter is the rear main seal mounting plate. It has a gasket that does leak more commonly than the rear main seal leaking but the repair is the same. Pull the tranny for access and replace it. Dorman supplies a replacement rear main seal with the plate. Very common and not expensive it is just the labor to remove the tranny for access that is trouble.

 

[justirv]

Hi, just saw a video about a small (maybe) block off plate near the starter that leaks at times and looks like the rear seal.

That's on driver's side rear and is a block-off (oil cooler) plate that notoriously leaks due to warpage. Replacing that gasket will give you temporary relief. Highly suggest replacing with a billet plate.

 

[West 1]

On the block off plate for the oil cooler I have had issues with that leaking on trucks, I started adding 2 gaskets, Fel Pro gaskets. Each gasket has a shape pressed into it to help seal against leaks. Fel Pro says each single gasket can seal up to .001 distortion without leaking. Adding a second gasket, careful to install them so the embossed lips oppose each other rather than tuck into each other has worked for me to seal some of these problem plates. There are also aftermarket plates available to do a better job sealing the block off plate. On modern head gaskets they use this technology to seal the high powered engines. Some head gaskets use 3 layers of MLS or multi layer steel. I have only done this on engines with the block off plate, I have not seen the same leaks on engines with the engine oil cooler lines mounted there. I have seen several with the Oil cooler hoses leaking and needing replacement after maybe 130,000 miles.

 

[OR VietVet]

On the block off plate for the oil cooler I have had issues with that leaking on trucks, I started adding 2 gaskets, Fel Pro gaskets. Each gasket has a shape pressed into it to help seal against leaks. Fel Pro says each single gasket can seal up to .001 distortion without leaking. Adding a second gasket, careful to install them so the embossed lips oppose each other rather than tuck into each other has worked for me to seal some of these problem plates. There are also aftermarket plates available to do a better job sealing the block off plate. On modern head gaskets they use this technology to seal the high powered engines. Some head gaskets use 3 layers of MLS or multi layer steel. I have only done this on engines with the block off plate, I have not seen the same leaks on engines with the engine oil cooler lines mounted there. I have seen several with the Oil cooler hoses leaking and needing replacement after maybe 130,000 miles.

You get a billet replacement plate, problem solved.