hey guys i got a 2003 hummer h2 and i have a leak under the truck every morning and im pretty certain its probably the rear main seal - due to the history of hummers with this problem. Is there any way I can just crawl under and make sure its the rear main before actually getting it done? Because I found a shop to do it for a decent price but hoping not to pay an extra $100 for 'diagnostics' however if thats the recommended way to go, then i guess ill have to do it. Also lets say we get it done, once everything is taken apart is there anything else i might as well get changed since the tranny etc is already out?

thanks!

 

Add Tracer Dye, then start from the top to find the source.

 

Tranny is a BIG job. I would not have them do a tranny swap if yours is fine right now. How big is the leak. I might just leave it for now and add oil as needed. Then when your tranny goes(which it will if your hummer experience is like most of ours) I would do the rear main. How many miles?

 

makes sense ive got 255,000 kilometers on original engine and tranny, both drive good as new as i did periodic fluid chages

 

do these pics help?

 

A rear main seal leak will cause oil to drip from the bottom of the bell housing at the front of the transmission.

 

HummerZ makes a good point. I know this is going to sound stupid but check the oil pressure sender at the rear of the intake manifold. Mine went bad on my 06 and created the same mess. If you do have the rear main replaced also replace the plate on the rear of the motor, these are know for problems.

When I had my 06's 4L65 replaced I did some checking on the leak points of an LS, they are known for problems with the rear cover plate warping or porosity causing leaks. Its a few bucks more to have it replaced and this way you know your covered until you retire your H2.

Hopefully its the oil pressure sending unit, sitting on top of the radiator support it's easy to replace it and considering the mileage I am surprised it still works anyway. lol

 

best to clean up all that mess so you can determine where it is coming from.
but i second the oil pressure sensor theory it is a known leak point they separate internally and leak.
another known area to check it the plate that holds the oil cooler lines above the oil filter, in your pictures it is wet the gasket goes bad.
if you want to look inside the bell housing for oil coming from the main seal pop off the shiny but covered in oil metal circle cover on the bell housing in your picture.

 

Thanks for al the help! And sorry I’m a noob. I heard about the bell housing thing, is thst what it seems like in my pics or is it impossible to say? I heard if I pop the cover off and look inside and there’s oil everywhere inside there then it’s definitely rear main. Is that true? Can I just pop it off wirh a flat head screw driver??

my plan was to wash it underneath at a card wash really good and then look again. Is that the best way to get it clean underneath??

 

Looks like some valve cover leaks too. Check oil pressure sender, crank sensor and cam sensor. All will leak eventually. Also the oil cooler lines on driver side.

Tim