Just completed road trip. Thanks for everyone's input! First time ever that I've takin' this thing that far on the road before, and have gained confidence in it now. . . well, almost.

Noticed in stopping at rest stops that there was a slow drip coming from the back on the engine. (engine oil that is) So I wondered to myself, is that the rear main seal going, or is it an indicator that the CDR is not doing it's job? Worse yet, if it is the rear main, is that an indicator of something else inside the engine, that I really, really don't want to ask 'bout?

Get back in there and look with a flashlight and make sure it's the rear main seal and not a valve cover or the place where a distributor would go on a gasser block. Rear main seals will lower the oil level in the engine 1-2 qts depending on the size and location of the leak.

Check your oil cooler lines.

There are a few leaks around the cooler line crimps. That's a whole other project that I have to get on. As for the rear seal, as you look under the engine between the engine and the tranny. The bell housing where the starter is, there is a little looks like a weep hole. The oil is coming down there.

QM, where is the distributor on a gasser block anyway? Been too many years since I have looked at one of them. Every ting I've owned has been smaller engines, and electronic at that.

It's called the oil pump drive and located at the rear of the block in the valley, toward the passehger side slightly

This leak is picking up speed, gotta look deeper into this now. How hard is it to change the rear main on a 97? The Haynes manual only shows the picture of the steam-cleaned-never-been-run turned upside down block neatly taken apart picture. Now, as for the rest of us, is that something that can be attempted in the driveway, or something a bit more complex?

you would have to pull the engine out enough to work on the rear of it.

Uhgg. Not sounding good. My boss' 350 had a leaking seal. He said they had some kinda tool they just reached in through the oil pan and changed it from the inside. I was hoping since this was another GM product, I might, just might get that lucky.

Ask billman or another mechanic.

Are you SURE it's not a loose valve cover leaking into the valley and then down? Just asking, because it's easy to check and can look exactly how you describe. I had the same concern only to find out that my valve cover on the drivers side was not quite as tight as it should have been. Might not be the problem, but it only takes a minute to check and could potentially save you hours. I don't claim to know anything about these engines, just had the exact same thing happen to me and also thought it was the main seal. Never in my life did 3 or 4 loose bolts feel so good :):) good luck!!!

Start by removing the flywheel cover, wash off as much muck and oil as you can reach with a can of brake-clean spray. Start the engine and watch, with a flashlight, you may see the source of the leak. If it's coming from above the main seal, investigate all of the areas on top and at the back of the engine.

A rear main seal leak will be obvious from under the truck, with the engine running. Most often, it will push the oil out and onto the crank flange. The rotating crank will sling the oil all over you!! Wear your safety glasses!

Start by removing the flywheel cover, clean as much muck and oil off as you can with a spray can of brake-clean. Start the engine and observe, with a flashlight, you may see the source of the leak.

The rear main leak can be obvious. Wear safety glasses, the oil comes out onto the crank and is slung off, usually onto your face! (Experience, here!)

If the main and the lower pan seal area are dry, check the above-mentioned oil pump drive and all other sources on top and at the rear of the engine.

I also have the same problem. I removed the flywheel cover and can see that the rear main is leaking. I have 4" lift kit to the suspension. It appears to me that I have plenty of room to remove the oil pan without lifting the engine. Anyone know if a 4" lifted suspension is enough? I have replaced rear seals in some gassers in the past. I assume that this is the same procedure. I assume the oil pump is attached to rear main cap and needs to be removed and then remove the the main cap. Replace the seal, inspect the bearing and hope that it is still good. Reinstall cap and torque back down. Replace oil pump and pan and be good to go. Now, this seems pretty simple. Did I miss anything such as special tools or timing issues with the oil pump?

I don't know if 4" lift is enough, but any time I need extra room to work under my suburban, I put it in 4 LO and drive it up onto concrete blocks. Maybe not the OSHA approved way of doing it, but if you're careful and chock the wheels it gets the job done.

Sorry about the double - post above, got confused again! If you raise the vehicle and support the frame, let the axle drop down, you gain some clearance. It's enough on the '80s models, don't know about the newer ones. The only one I've done was a 5.7 gas engine and I had to drop the differential, IFS type.

What year did the one-piece rear main start? Those are a piece of cake and can be put in without removal of the pan. Pull the trans/transfer case back for access.

I just did my rear main seal while doing a clutch replacement. You have to pull engine or drop trans. Not sure which is easier. The flywheel has to come off. Its not a cartridge style that can unbolt. It has to be put on squarely from the back of the motor. I borrowed the GM tool (J39084 I think) that bolts to the crank and presses the seal on.

You can pivot the front axle as much as you can and lower the passanger side some then persuade the oil pan off but its tight. I had my trans out and it still took a while to sweet talk it out.

4" is not near enough ground clearance. I was as tall as my jack stands could go and on top of 4x4 blocks and a couple of 2x6's and it was not fun.

My NV4500 wasn't too too bad to drop as it seperates at the tranny/bellhousing. An auto might be a bear. Not sure if I am just that slow but it took me several hours to just drop pan and do seal. GM uses the rubber sealing goo on the pan and it takes a while to clean in up. Heck its taken me a full weekend and a half plus a couple of hours in the evenings and I am only 90% back together. Oil cooler lines, remote filter, clutch/pp/flywheel/slave/pilot brg, oilpan gasket, and rear seal. Uhhggg!