Chevy & GMC Vans

I am thinking I did not do the new gasket correctly as it seems I have a drop of oil at the bottom of the diff. I'm not sure if it is because of a leak in the 'new' gasket yet or if it is perhaps not having the fill cap in tight enough, or something else. I just noticed a drop of oil on the driveway, and after getting some new rabbit cages with my wife I looked underneath and saw the drop of oil (or something that looks like it) on the bottom of the diff. If it is a leak, it is really slow, and I think I will order a new diff cover before I fix it. I just have to decide if I want to pay the $20 or so for one like the factory one, or the $150 or so for a fancy one with fill and drain holes in it.

Did you wipe all the extra oil that came back out when the differential was full? I would get a can of brake parts cleaner, and completely spray the entire differential until it is absolutely clean.

Then, take it out for a drive. When you come home, jack it up and inspect for leaks. Remember that gear oil is very thick, and it will take a while to travel down the differential, and enough of it forms a drop. Unfortunately, you may have a leaky pinion seal, which is re-engineering the space shuttle compared to changing the axle seals.

That is exactly what I think has happened, because I did not clean off the oil that dribbled out (at least not more than a wipe with a rag) when I filled it up. That is why I am not horrible worried at this point. When I get some time I will have to give it a spray with some brake cleaner.

This past week my free time was taken up doing the exhaust on my wife's mazda. I did a quick job on it a while back using clamps to hold stuff together, but as they are prone to do they came loose. So I decided to weld stuff together, and that ran into a few issues getting parts to re-attach the exhaust. It is back on and working well, so maybe Monday I can give the diff. a spray with brake cleaner, and see what I see after driving around. There was no leaking around the pinon seal when I started the job, so I doubt that is where the leak is, but if it is, I am game to do it because with the help from my friends here, I'm sure I can fix almost anything on the van. It is amazing how the more I fix the van, the more confident I am about doing other things that before I would never have considered.

Thanks for the suggestions. I had not thought of hitting it with brake cleaner, and I just happen to have a can sitting around. I should really buy it in bulk I use it so much.

I cleaned off the diff this afternoon, and now I can wait to see if it was remaining oil that dribbled out of the fill hole while filling it slowly making its way down the diff, or whether I messed up on the RTV gasket maker. If I could have found my zip ties I would have zip tied the air lines for air adjust shocks better as well. Oh well, I will be under there again

I have not yet jacked up the van, we were out all day today, but I did look under it yesterday after going to the beach and back. There is a drop of oil hanging off the bottom of the diff. I will jack it up and see where it is coming from, but from what I could see without jacking it, the leak is from around the cover. I will know more later this week. I figure I will order a new cover if it turns out to be around the cover, and replace the old one while I am redoing the gasket.

I decided since the old cover was looking pretty rough, and I was taking it off anyway, that I would put on a new one. This time everything worked great. No leaks so far. I took the chance when I had it jacked up to put some more zip ties on the air lines for the shocks. I am quite satisfied with how they are attached now as well.

for surfaces that need to be rtv sealant sealed, brake cleaner is good, electric parts cleaner it good, even isopropyl alcohol is good. the thing is you want is a solvent that does not leave an oily residue, and evaporates completely.

It sealed up nicely this time. When I went to take off the old cover there was what looked like a rather large damp spot on the diff cover that was not there after I cleaned it up with brake cleaner to determine where the leak after I re-installed it was from. The inside of the cover looked good to me, but maybe there is a pin-hole through it. Either way, I have a new cover on, and feel better about it.