Transmission Fluid Change Drain Plug

[AXE]

Well, I finally got around to my last maintenence project before summer hits. I am at 16k miles and wanted to get a look at the transmission fluid. I estimate about 8k miles towing and of course lots of hot weather, city driving, higher speed highway too. So I consider my truck to fall into severe duty classification, but fairly routine HD use. GM calls for fluid and filter for severe duty at 35k.

So since I plan to do early/frequent maintenence and fluids on the transmission i wanted to get a drain plug installed on the pan. So to begin, I selected a location on the pan where the bung could be placed that would clear the Bison skid plate and there isn't a lot of clearance, so the forward position on the bottom of the pan was best for me. I got out a 1/4 inch drill bit and proceeded to tap a hole in the pan. The pan is thin do it doesn't take much and you v have to make sure not to go deep because there is equipment just an inch or so above the pan. The fluid is ultra low viscosity so thin like water and it drained quickly.

I then drilled the hole to 3/8 of an inch and smoothed it out a little with a fine file so it matched the bung hole perfectly. I took it over to my buddy's place who is a metal fabrication professional and he welded the aluminum bung in. I don't have any experience or an aluminum spool for my welder, so I didn't want any part of that. It came out really stout and clean. Not sure what the torque specs should be on this plug with a copper crush gasket, but I eased into into it from 10 ft lbs and stopped at 13 ft lbs and it felt good.

 

[AXE]

Before I drained mine, I checked the fluid level first with the stand pipe and it was about 3/4 - 1 quart "over full". Wasn't sure what to make of that.

So I refilled with 8 quarts and got the transmission up to about 170F and checked it and it still drained about 1/3 of a quart out from the stand pipe check plug.

I have an extra quart, so I think I am gonna add back in 1/2 quart just for good measure. I seen some guys says theirs was low and it took between 9-10 quarts to refill.

The system holds about 21 quarts, so a pan drain and fill is replacing about 40% of the fluid.

The fluid still looked pretty good and was just a couple shades darker and the magnets had a really light film of metal on them, so I do think the transmission runs fairly clean.

I am going to due a pan drain every 15k and filter and double pan drain every 30k. I did 2 gallons of fluid every 25k on my last two Allisons transmission trucks, but did the spin on external filters at 15k because it was so easy.

If your thinking about fluid change on your rig, I would want that fluid out of there by 25-30k if you work it. The problem with not having any dipstick forv reference, is you really have no way to pull a sample to see what it looks like. You can get some fluid from the stand pipe drain, assuming its fullish, but it may not be the best way to sample since fluid may be stagnant in there.

I think some of the valve body issues are caused by dirty fluid and heavier contamination. I'm gonna stay ahead of it and see if it makes a difference long-term.

 

[ZR2xBIZON]

Noice!!