Replacement of Rear Main Seal 2001 4.3 Vortec
 

I have a 2001 GMC Jimmy (S-10 Blazer) and am in the process of replacing my transmission. I've noticed an oil leak behind the flex plate. I removed the flex-plate and it looks like oil is weeping out below the main seal. I've noticed a number of bolts that appear to be holding in a ring/bushing around the main seal. Do I remove these bolts and remove the ring/bushing to remove the main seal? or I am i supposed to just pry out the main seal. I guess the issue that I see is that the leak is not right around where the shaft and seal meet but below this ring/bushing that is bolted in. I'm wondering if it's not my oil pan gasket that is leaking? I've attached pictures for your review.

Hey whats going on, just seen your post, I'm under my truck tonight and can see oil leaking near the rear main, along with the oil cooler lines. Just wondering if you did this repair and how did the process turn out? Thanks

It appears your main seal needs to be replaced and yes you need to remove those 4 bolts that cover comes off along with the seal inside of cover,not hard to replace and cheap.You can go ahead and change the oil pan gasket too, but you,ll have to lift the motor up.

Well, we're kinda bringing this one back from the dead, lol. But since it's here...

I'm looking at a leaking rear main, as well. Can you change it just by dropping the transmission? I always thought you had to pull the motor?

There has been some confusion regards to rear main seal 1st - rear main crankshaft is the outer visiable seal,you,ll see it after removing the flywheel ,it needs lubrication on inside of ring ,where it meets crankshaft, marine grade grease or clean oil 2nd- rear main bearing seal, this is for the main bearing not the crankshaft ,it is a different seal # it does'nt require lubrication upon installation and it is inside and only visiable upon removal of oil pan. hope this clears up confusion also ,be sure to specifiy which seal you are requiring of the two, it could be you,ll get the wrong one, if you,re not specfic.

Ok... I think I get it. The outer seal can be done by dropping the transmission, and that inner seal has to have the pan off (and the motor pulled.) I haven't really done much inspecting. I've been chasing an oil leak that I thought was the oil filter adapter. I've now noticed that the oil is leaking from the hole in the lower bell housing cover. I figured it was the rear main. If it can be done by dropping the transmission, I might take that on. I just really don't want to pull the motor.

We should further clarify something here,regarding removal of the rear main crankcase seal. This seal can be removed without removing the houseing ,that is those 4 bolts and the 2 securing the houseing to the block,that is a whole new kettle of fish. That would involve dropping the oil pan ,replaceing oil pan gasket alone with the rear main seal,that is the full deal. what you have to consider is it the main crankcase seal or the oil pan casket ? you can try the replacement of seal and see if that gets it ,otherwise you,ll have to go after the pan gasket,sometime the bolts get loose and need bolt sealent and thighting. You will need a special tool to press the rear main crankcase seal into place after you've plucked it out ,this tool attaches bolts to the rear crank flywheel bolt holes and press in the seal.

Just to post this for future searches etc, Before you go pulling the trans out etc, The oil cooler line adapter. (What the cooler lines,or just the lines for the 4wd) run into. there is a large oring and paper gasket in it. the oring dries out and leaks down the adapter,onto the bellhousing cover and out that little hole on the bottom and makes it look the the rear seal is bad. The oring kit is like 8 bucks online. replace this before touching the rear. As im sure alot of your problems could be this,as ive fixed several of them causing this issue.
Part # for the kit is
Dorman 82560 is what most of us will need if its the adapter. this kit comes with the orings etc. By the way,dont torque the nuts on the cooler lines super tight or you'll cut/pinch the new seals.

I'm aware of the oil lines and adapter. I've replaced both sets of lines and put new o ring and gaskets on the adapter. It did slow the leak down, but it's still coming out of the hole in the bottom of the bellhousing. I wish it had just been the adapter!

ahhh. Hmm. Check out the valve covers,and oil sending unit,maybe distributor gasket. if all that is clean....Good luck to ya.