2005 Silverado 1500 5.3L Odd Oil Leak

[Ian Mills]

I have a significant leak on the driver's side of the block. The oil is present above the rear main (replaced in 2022) and also above the oil pan gasket. It kind of looks like it's coming from the plug in the pictures which is on the driver's side at the back of the block about 3 inches above the oil filter housing. The block off plate for the optional oil cooler (I think) is visible towards the bottom of the second photo. The block and heads are dry and (relatively) clean above what can be seen in the photo. I don't see anything coming from the oil pressure sending unit (replaced in 2021).

 

The plug with the wires coming out of it is what I have been calling my block heater, however I've been googling around and it seems like a traditional block heater would be in a freeze plug on the passenger side of the truck.

 

The first question is: is this a block heater that goes into the oil gallery or should that be a coolant passage in that location?

 

The second question (related) is: is that where the leak is coming from?

 

I could be convinced that it's the oil pan gasket but the oil starts about 2 inches above the gasket and that seems like too much to me.

 

Happy to entertain theories and ideas. Thanks in advance.

[davester]

From what I can tell, LS engines mostly switched away from freeze plugs to screw in plugs (and screw in block heaters), and rear drivers side seems to be a common spot for the block heater.  More expensive, but also more reliable/easier to keep sealed and easier to replace.  And no there is no heater that goes into the oil gallery, it only goes into the water jacket.

 

Could be rear main seal.  But I would suggest cleaning it off and then seeing, rather than guessing.

[davester]

Also, it's WAY easier for people to figure out what's going on if you orient the pics better, such as say, the physically lowest part of the pic is at the bottom, not taking a pic at an odd angle.