A rear main seal leak is likely the most expensive oil leak any 3.0 or 3.3 liter V6 owner will be tasked to repair. While not common, the rubberized seal at the back of the engine, sealing the crankshaft at the back of the engine block where it bolts to the flywheel, will eventually dry out and leak.
Because the rear main seal is hidden by the transmission, you can’t see the seal itself leaking until the transmission and flywheel/flexplate is removed. Often it isn’t the rear main leaking at all but rather the rear oil galley machining plug that’s the source of the oil leak. The heavier the oil leak the more likely it’s the rear galley (especially on later 3.3 liter engines). Here’s the back of the engine, the oil galley removed, and everything labeled:
3MZ rear main, galley leak
In the above the galley plug is removed, awaiting a replacement plug and crush gasket.
If you’ve got an oil leak from the rear main area on any Toyota or Lexus 3.0 or 3.3 liter V6, you should replace both the rear main seal and the rear galley plug. You don’t want to have to pull the transmission back out to replace anything back there in the future, and usually both have some sort of leakage regardless upon close inspection.
As Minnesota’s premier independent Toyota and Lexus specialist, CARspec has both the technical expertise to repair any Toyota or Lexus rear main seal area leak in only a few business days. If you’ve got a rear main seal leak and are in the Minneapolis metro area, don’t hesitate to give us a call and set up an appointment today!
