2013 3500 Extended, 6L90 transmission.

I’m trying to drop the transmission pan to do a fluid/filter change. The rear pan bolts are directly above the exhaust line. I took one of the front bolts out and tried to wedge it in the rear space between the exhaust and the pan to gauge if I will even be able to back the rear bolts all the way out. It was longer than that space which leads me to think the exhaust has to be dropped just to get 3 pan bolts out. Is there a trick to this or do I have to drop the exhaust?

 

I've seen some videos on trucks where you can undo some of the mounts, use some ratchet straps, and pry the exhaust away enough to get the pan out. Put a drain plug in there before you put it back on! I haven't done mine yet.

 

When I dropped my xmsn pan to replace filter and fluid, I had the same issue. My exhaust had just enough play that I could shove it out of the way to barely get the bolts out. The design is poor, and you'll get a lot of mess on the exhaust if you don't plan for it. The van was cold, so I laid some plastic over the section of exhaust under the xmsn pan to prevent the fluid spilling on it. After everything drained, I removed the plastic and the exhaust stayed clean (spilled fluid will just burn off, but I wanted to avoid that).

 

big crow bar

 

I had the same problem on my ‘02 Express. I ended up removing the rubber exhaust hangers and lowered the exhaust to get the necessary clearance. It was a huge PIA. A year later, when I had to have the transmission rebuilt, I asked the tech what the secret was to getting the clearance with the exhaust, and he said that they loosen/remove the rear transmission mount and that allows them to raise the transmission enough to get the clearance. I haven’t tried that trick yet, but will give it a shot at the next fluid change.

Peter

 

2 things about $30 will make life better. #1. Put drain plug in pan where there is a little room on the inside. You should be able to stick a flat magnet on outside anywhere. #2. Change fluid and filter again in about a month..Much easier to change twice than do a flush on 1st change. #3. Stainless exhaust bolts will be a lot better than bolts that will rust shortly.
. Acetone and trans fluid mixed makes a fairly good breaking fluid for rusty parts

 

I just ordered the filter and gasket to do this job. I've been concerned about clearance as well. I did undo the hangers yesterday just to see if that gave me more room but the exhaust didn't move much. (We have the 4500 chassis under a class C rv) I'll try undoing the trans and jacking it up slightly. I'll report back next week.

Gary

 

Update:

I tried a crow bar to pry the exhaust out of the way. No dice. I loosened the rear transmission mount and tried to pry the rear of the transmission upward. Also tried a bottle jack. No dice. There is just no flex because the exhaust, motor, and transmission are all bolted together and it's tight. The only way I can see doing this is unbolting both sides of the exhaust (cat to manifold) and the rear section, essentially disconnecting the entire Y-section. I can't do all this on my incline gravel driveway with no safe way to jack it up. Something that crossed my mind earlier is that perhaps Chevy used 3 shorter bolts in the rear of the pan that are directly above the exhaust. Have any of you noticed this when removing your pan?

 

Update:

Finally got around to trying to change my fluid/filter again. Turns out I'm an idiot and measured wrong last time. The 3 rear bolts directly above the exhaust line will come out without having to move the exhaust. The bolts are almost exactly the same length as the distance between the exhaust and the pan. Once they have been backed all the way out, there is just enough play to remove them because the ends are slightly tapered. I loosened them with a 10mm open end wrench, then used my fingers to remove them with both hands. One hand had to be on each side of the exhaust, with the fingertips from each hand turning the bolts. There's not much room and most of is done by feel only. They really weren't that difficult to remove and replace, just takes some time and patience, both of which are a great alternative to removing the exhaust or paying someone to do it. It did take less time to maneuver the bolts out than it would have taken to drop the exhaust. Once those 3 bolts were out, the rest were cake. Changed the filter, cleaned the pan, installed a new gasket, and put it all back together. The rear 3 bolts took a little time again but it was not difficult. I did this on my back without even jacking it up. I'll do it again in a week or so to exchange the fluid again, should be a little quicker this time now that I know what to do.