I have done some research on the leaky oil pan issue (which I have) and decided to tackle it this next spring. In addition, I have what I believe to be a rear main leak. I was hoping to tackle both at the same time (and replace the oil pump even though it works). It sounds like I just have to jack up the motor 4.9L, loosen the wiper motor, and the pan should pull out. Will I then have access to the rear main seal? Thanks!

 

I just did this job over the past week in my driveway. Pain in the ***, but worth doing right. It should be said that I would rather have an ingrown toenail pulled without anesthetic than work on my truck, even when it saves me a grand. The good news is that if you do some other things while you are in there, you can make some serious improvements to the way your truck feels when driving.

This is the way I would do it: You complete the steps necessary to remove the oil pan. Then lower the engine back onto its mounts without reinstalling the oil pan. Now it is time to remove the transmission. Drain the transmission, and disconnect the drive-shaft from the rear end of the transmission and the input of the transfer case. I do this to prevent the drive-shaft from hanging on the U-joint. Now get something like a jack to support the transmission and undo all of the bolts that hold the transmission in place. Disconnect the clutch line and/or shifter linkage and any other connector. Now carefully lower the transmission onto a back board or a dolly and take it to the work-bench. You will now need to remove the clutch and flywheel if you have a manual or the flex-plate and torque converter if you have an auto. Now you will have access to the rear main seal. Replace rear main seal now being very careful to get correct placement and no damage (however slight) to the seal.

Now is the time to do some other maintenance items while you have the chance. You mentioned that you would be getting a new oil pan so thats off the list. How does your shifter feel? (if you have a manual) If it has a great deal of slop in it, now is the time to replace the shifter bushings. Pop the shifter cover off the top side of transmission and just replace the bushings and cover gasket, torque the cover back on and you're finished restoring the feel of your shifter, simple as that. If you see anything that you think might be wrong while you are under there, don't hesitate to fix it while you have the chance.

I know what you're thinking, why didn't I put the new oil pan on before removing the transmission? Answer; because I can't stress enough how important it is when doing an oil pan and gasket job to get block mating surface and the pan mating surface, totally clean and free of oil. That means letting the block drain for as long as you can so when you put the new gasket on, there won't be any oil on either side of the seal that will allow it to push out from the pan seam.

So now its time to put everything back together being sure to align the clutch correctly and get the transmission back in the truck. Once you have this done, (A long while later) you must now complete the oil pan and gasket job. Raise the engine back off its mounts and thoroughly clean the mating surface on the block. Here is where I use some of my aircraft methods to make absolutely certain my gasket won't push out or leak. I get a clean large disposable roasting pan and put the gasket in that. I coat both sides of the gasket with oil-proof permatex make-a-gasket. I then take four lengths of silk thread and on each side of the gasket one piece runs inside the bolts and one piece outside the bolts on both sides making sure that there are at least three inches of overlap for each piece of thread and install the gasket that way being sure I haven't messed up the silk thread. Torque on the oil pan following the tightening sequence in the manual. Lower the engine, tighten all of the mounts and re-fill with oil as you would normally.

It surprises me that so many have never heard of the silk thread and make-a-gasket trick. when you build a high performance aircraft engine, this is how you seal the crankcase halves that will be running upwards of 175 PSI of oil pressure. They very rarely leak. This is an excellent correction for the gasket push-out problem.

This repair is a huge pain in the *** and awesomely frustrating. Good luck.

 

Thank you for your advice! You are right, as long as I am doing the work, I might as well check into other preventative maintenance issues. The shifter feels fine, but the clutch could probably be serviced. I have to say that I have never heard of the silk thread and make a gasket thing either. I am having a hard time figuring out how the silk thread helps though. If my time were an issue, would I have to remove the transmission to replace the rear main seal, or would I have access to it by dropping the oil pan? Thanks in advance!

 

As far as I know, the only way to get the rear main done right is to drop the transmission. Then again, I'm not exactly an expert as I haven't tried it without pulling the transmission. If I were you, I would try to lay hands on a dealer service manual, which shoud be able to expand a great deal on the little I know.