Not Sure If Your Rear Main Seal Is Leaking?

[JonnyTahoe]

If you have oil dripping off all these spots under your Truck your rear main or rear main plate is probably leaking.

 

[fasteddy]

Yup
Been there.
It can also be the oil pressure sensor (less seldom) which is at the top rear of the block.

Oil looks fresh though. And oilpan and bellhousing and bolts look very clean.

 

[OR VietVet]

Maybe even the engine oil cooler line at the plate or the block off plate if no oil cooler lines.

 

[mattbta]

Crazy timing. Here's mine this weekend after blasting it clean with brake cleaner. Started it up and saw this: (It's either rear main seal/cover or I did a bad job on the oil pan gasket or BOTH) Thoughts? All new stuff within a year: Oil Pressure Sensor, Camshaft Position Sensor, Crankshaft Position Sensor, Oil Pan Gasket, Valley cover Gasket, new Blockoff Plate.

 

[wildcatgoal]

If you replaced the oil pan gasket and it still leaks, then consider the RMS. Don't go doing a RMS before replacing (properly) the oil pan gasket.

And when you do replace the oil pan gasket, you need to put sufficient dabs of RTV at all 4 corners front and back where the block has splits. If you don't, it'll leak. Stupid design, frankly, to have a pan gasket seal over a split surface. Absolute dumbassery. Lots of people don't do that RTV part right.

When you do replace the RMS, you can fix the RTV from the top of the installed oil pan and seal it up again (you have to, anyway).

 

[JonnyTahoe]

I like your aftermarket block-off plate. The leaking of these engines in one of the most annoying issues. Your way ahead of me with all that you have replaced so far.

 

[mattbta]

I had a shop replace the oil pan gasket a couple years ago and still had a small drip. During lockdown, I pulled the oil pan to look for sludge as I replaced my Castech heads so I put a new gasket on then. The leak has gone from a few drops to totally soaking cardboard underneath it after a drive or two. I could always do the gasket again as it's fairly easy with 2WD. I'm really sick of it though so I'm about to go drastic and have a dealer look at it. I've got a SacCity Vette barbell to go in when it gets pulled, too.


EDIT: Don't mean to hijack your thread. Just looking for opinions as well, our's looks pretty much the same as far as where the leak shows up.

 

[JonnyTahoe]

I had a shop replace the oil pan gasket a couple years ago and still had a small drip. During lockdown, I pulled the oil pan to look for sludge as I replaced my Castech heads so I put a new gasket on then. The leak has gone from a few drops to totally soaking cardboard underneath it after a drive or two. I could always do the gasket again as it's fairly easy with 2WD. I'm really sick of it though so I'm about to go drastic and have a dealer look at it. I've got a SacCity Vette barbell to go in when it gets pulled, too.


EDIT: Don't mean to hijack your thread. Just looking for opinions as well, our's looks pretty much the same as far as where the leak shows up.

Sounds like mine exactly I get my cardboard from Costco and it comes in handy for cleaning parts too. I will be doing the oil pan this week but I already know that's not it. It leaks for hours after you turn the engine off and the oil is not over the top of the oil pan when the engine is not running.

 

[Greg Kulbick]

I was just under our Tahoe Friday night trying to clean up under there and pinpoint where the oil is coming from. I think the block off plate is fine. I didn't see much of anything when looking through the hole in the bellhousing, so I'm keeping my fingers crossed its just the pan gasket.

 

[mattbta]

@Larryjb -- did yours look like this?