2003 Silverado 1500 HD gearbox fluid change

This week I finished the snow blower that has been in the shop for a month. There actually wasn't much time involved with working on it. The snow blower spent all its time sitting on the work bench waiting for parts. It had bad gas in it and needed the carb to be rebuilt. That's an easy job if you can get the rebuild kit. I had ordered it on New Years Eve and I finally got it on Tuesday. I rebuilt the carb and everything looked good except the needle valve. It was different and would not work so I took another trip to the parts guy and luckily he had the one I needed at his shop. I put it together and it fired right up. I delivered it and got ready for the next job. It was fluid changes for the front and rear differentials, the transfer case and the transmission along with a filter change for the transmission on a 2003 Silverado HD. It wasn't a bad job even with the bad weather and snow melting on me. Here it is in the shop. I was worried I might have to leave the door open because it wouldn't fit in the garage but it fit, just barely. I cranked up the heater and the music and went to it.

 I drained all the fluids first while everything was warm to get as much stuff out as i could.

The rear differential has a drain plug on it which makes it nice. The drain plug has a magnet on it and this one was really clean. There wasn't even any sludge on it like there normally is. I didn't remove the cover because the magnet and fluid looked so good. If it looked bad I would of pulled the cover and checked out the gears.    One thing you should always do when dealing with anything with a drain and fill plug is to always remove the FILL plug first. It would be pretty crappy to remove the drain plug and then not be able to remove the fill plug. Makes it hard to fill it up when all the fluid is drained.

 This truck takes full synthetic fluid in the rear differential. Some limited slip differentials require an additive to be put in but this on just requires synthetic gear lube. I like Mobil 1 fluid and that's what I put in this one. Royal Purple is really good also but it's double the price. Not sure if its worth that. This rear end has plenty of room to fill up the differential using the bottles of gear lube themselves.

 The front differential has drain and fill plugs also. The magnet on the drain plug was pretty fuzzy. I flushed a little fluid through it to get it cleaner. There is no cover that can be pulled on the front like the rear so that's the only way to do it. I suspect the fluid hadn't been changed before on this differential. It surprised me because all the other fluids looked really good.

 The front takes regular gear lube but a different weight. I picked up Valvoline because it was a good price and I like Valvoline also. This isn't the funnest to fill. It looks pretty accessible but there's not enough room to lift the bottle up so it will drain into the housing. I have a Matco tool that works good. It is basically a huge syringe that you can suck up fluids and then push them out where you want them. I should of taken a picture but I didn't. It filled it up pretty quickly which is a good thing when your dealing with gear lube. Gear lube smells horrible and the smell doesn't go away when you get it on you. Ellie came out in the garage and said it was stinky. I suppose it was.

Here is my Matco suction gun that I used to get the fluids in. It works awesome.

 The transfer case was next and so I removed the plugs and let it drain out. Be very careful and use the proper torques on the transfer case plugs. The case is made out of magnesium and if you over torque the plugs they will strip.

Make sure you get the right fluid also. If you have insta trac it requires this fluid. Get it from the dealer. It's a specialised fluid that wont corrode the magnesium and will work with the push button 4 wheel drive. Always check that you get the right fluids or it may cause some expensive damage.

I also did the transmission and filter but I forgot to get pictures, It takes a little more work then just pulling the plugs and filling it. This pan has a drain plug so I drained it and then removed the pan. To remove the pan you must unbolt the shift linkage bracket on the passenger side of the trans and remove the transmission support (cross member). It only takes 6 bolts and 2 nuts to get the support off. Just make sure you support the transmission with a floor jack before you remove it all the way. Once those are out of the way you can remove the pan  This pan was very clean. There was the usual sludge buildup on the magnet but it was very minor and the inside of the pan was clean. The filter just pulls out and I decided to leave the original seal in and just replace the filter. There is some debate on this but the seal looked to be in very good condition and it just isn't worth the risk of gouging the housing if you don't need to. Sorry theres no pictures but it's pretty self explanatory. Install everything in the reverse order of taking it off and then fill up the trans through the dipstick tube with Dexron VI transmission fluid and your good to go. So that was the project for this weekend. Next weekend I will be changing the transmission fluid and the hidden filter that Honda doesn't tell you about in Dixie's Honda Odyssey along with the cabin air filter. That is if the parts show up this week. See you then.