Man...no rest for the wicked. I get one fire put out and another one pops up. Oh well...

This morning, I noticed some oil or grease spots on my rear bumper and tailgate, so I decided to take a look and see where it was coming from. (I'm not sure what exactly it is; it's very thick like grease in some areas and appears to have a silver shimmer on my fingers, but it looks like it's "running" on my gas tank and bumper/tailgate like oil would). After fighting with jacking/blocking the truck up, I crawled under the L and noticed quite a bit of grease/oil on the rear of my gas tank, a little on the underside of the bed, and a light spattering on the spare tire. It doesn't seem to be the differential because it's full and there are no "wet" spots around the perimeter of the seal. There's no oil on the driveshaft or u-joint, but it appears that it's whats slinging the oil on the gas tank and underside of the bed (it moves in a CCW direction, correct? That inside/rear of my gas tank is covered with whatever it is). There is no oil whatsoever forward of the front of the rear tires (there's a crossmember under the bed that is basically a dividing line for me). It's really odd and nothing I've seen before. I mean, my rear passenger-side shock is rubbing, but it's not leaking (and wouldn't produce this kind of mess, I don't think). I'm baffled. If any of y'all have any ideas of what to check or where to look for clues, please let me know. Thanks.

DUCK

 

the only thing i can think of is that its getting flung all over from something turning which leads me to think its the driveshaft flinging it. then that leads me to believe its either the tail seal on the end of the transmission where the driveshaft slides in, or its the seal on the front of the rearend, where the driveshaft bolts to on that end. if its the first one i mentioned, it will be transmission fluid, pinkish red in color, if its the second one i said, it will be a much darker color. those are the only 2 things i could see that can leak and fling all over the place. im sure if you get under there and look real carefully, something somewhere has to be wet and leaking. then again theres always the chance you ran over something in the road and it splattered everywhere. hope this helped and let us know what you find out.
Mike

 

I had the same symptoms when I first picked up my Lightning early last year. Unfortunately, the problem was a bad transmission... the bell housing was leaking fluid all down the driveshaft and, well, you know. I had my transmission replaced after only 300 miles, but everything's been peachy since then.

My advice: prep the truck, take it in, and make sure they take a look underneath the truck, especially the transmission.

If the search function works back that far, take a look for my posts as username lightning_svt in March or April of 2000. Good luck!

~rick

 

Thanks, y'all. What's odd, though, is that there's no oil or anything anywhere on the driveshaft or rear u-joint. I jacked the truck way up and crawled underneath it with a light to snoop around. I wiped down a lot of the surfaces with a white paper towel to see if there was any residue on different parts, and the only residue was on the rear of the gas tank (started just above the "lip" on the rear cover and ran down and about halfway to the front...this was a pretty heavy coating) and two other places where it appeared to be slung/sprayed lightly. There was nothing anywhere else; I checked all around the u-joint and where the driveshaft enters the rear diff. There wasn't anything on the shaft, u-joint, or just behind the rear of the u-joint (where the three or four bolts were). I think what I'm confused by is the fact that if it was being "slung" by something, the active part would have at least some residue on it.

I'll keep y'all posted as to what I find out. After typing the above message, I went to the car wash and used the degreaser to clean the underside of my truck. Man, the gas tank looks like new. If something appears within the next few days, I'll have to spend some time on a lift tearing things apart.

Thanks again for the suggestions. I appreciate them.

DUCK