Transmission Fluid & Filter Change Help

tomo62 · June 15, 2008

Hi,

Just want to change the trans fluid and filter in my friends 2002 Yukon.

Was going to drain the fluid by disconnecting the transmission cooling line at the radiator - but that is a whole lot difficult to access.

Decided to drain the fluid from the pan in the traditional fashion - but the plug must be welded in - can't budge it.

Thought about dropping the whole pan off - but the shift cable runs underneath it. See one bolt that holds it - easily accessed from the rear with a Torx driver, but it is held somewhere else that I can't see.

I can see that I might have enough room to wiggle the pan off around the shift cable - but think I will ask for advice.

any hints to do this apparently simple task!

Thanks

tomo62

C & A s Dad · June 16, 2008

I have done this on my truck and can offer some advice.

If you have not rounded the edges of the drain plug I can tell you how to get it out. You will need a very good quality impact style (black) 6 pt 1/2 drive socket and a good pull handle. Get the truck up high enough that you can get directly under the pan. Push up on the pull handle and socket to keep is good and square on the drain plug and it should come out. If it still does not move, heat it slightly with a small propane torch. These plugs are installed at the factory with a mid strength thread locker chemical like Permatex loctite.

There are 2 torx screws in the sift bracket and they are not too hard to reach but as you said, you have to access them from the top. Some people bend the bracket out of the way but I do not recommend it.

Once you get the pan off, you will find the clearance between the valve body and the exhaust crossover pipe could be tight. If you cannot get the pan back on, simply loosen the rear trans mount just a little and jack up the rear of the trans about 1/2 inch.

If you decide to flush the system by disonnecting a line, you can get to the aux cooler line very easy by removing the grille assy. You can have the grille on the ground in less than 5 mins and then it is very easy to get to the cooler lines mounted in front of the A/C condensor. Slide the plastic shiel back on the line at the trans cooler and remove the small c clip with a small screwdriver. Be careful not to loose it as you will be reusing it. Now you can add some length of hose to the line and flush the system if you want to. There are some great instructions on Amsoil's website if you care to do this.

Let me know if this works out for you.

daddysLBZ · June 16, 2008

tomo62 · June 16, 2008

Thank You - and I really mean it for taking the time to give such good instructions.

Working with limited resources here and didnt want to start something I couldn't finish. The drain plug on the pan is in super tight and I may have rounded the edges even though I was using a socket. At the risk of some rubbishing, I have done most work on Japanese cars for the last 10 years , and I find some of these head sizes on GM vehicles to be strange, such as the 15mm for the drain plug. 9/16" won't fit and 5/8" is too big. Even with a metric socket wrench - the sockets never seem to fit properly (Craftsman set). With a 12, 14, and 17mm socket - you can do most things on a 'rice burner'.

I will look to the Amsol site to see what information is there - I think it's better to get a full drain on the trans as the torque converter holds a lot of 'green' (contaminated) oil that can't be extracted by just draining the pan.

Perhaps it's just me - but shouldn't such a routine maintenance item be a little more straight-forward?

Thanks again, I'll post again to tell you how this fiasco turns out!

I have done this on my truck and can offer some advice.

If you have not rounded the edges of the drain plug I can tell you how to get it out. You will need a very good quality impact style (black) 6 pt 1/2 drive socket and a good pull handle. Get the truck up high enough that you can get directly under the pan. Push up on the pull handle and socket to keep is good and square on the drain plug and it should come out. If it still does not move, heat it slightly with a small propane torch. These plugs are installed at the factory with a mid strength thread locker chemical like Permatex loctite.

There are 2 torx screws in the sift bracket and they are not too hard to reach but as you said, you have to access them from the top. Some people bend the bracket out of the way but I do not recommend it.

Once you get the pan off, you will find the clearance between the valve body and the exhaust crossover pipe could be tight. If you cannot get the pan back on, simply loosen the rear trans mount just a little and jack up the rear of the trans about 1/2 inch.

If you decide to flush the system by disonnecting a line, you can get to the aux cooler line very easy by removing the grille assy. You can have the grille on the ground in less than 5 mins and then it is very easy to get to the cooler lines mounted in front of the A/C condensor. Slide the plastic shiel back on the line at the trans cooler and remove the small c clip with a small screwdriver. Be careful not to loose it as you will be reusing it. Now you can add some length of hose to the line and flush the system if you want to. There are some great instructions on Amsoil's website if you care to do this.

Let me know if this works out for you.

C & A s Dad · June 16, 2008

There are theories as to why GM used the thread locker on the drain plug but it has caused many people to round the head off. The shifter bracket is not that bad once you realize where the two torx bolts are.

I flushed mine at home using the Amsoil instructions.

Summary:

1) Drop pan and change fluid and filter

2) Refill with approx 5 qts of new fluid

3) Remove line and add extension hose and place end in a clear container

4) Have someone start the truck and fill the container. Make sure they are watching you to know when to kill it. Pump a qt out at a time.

5) Add a qt.

6) Pump out another qt.

You will do this about 10 times until you see the fluid running clean. You will notice it to begin to change color about the 4th or 5th qt you pump out.

Hope you can get that drain plug out. Be sure to have a new one on hand to replace it.

tomo62 · June 17, 2008

Thanks for the vote of confidence.

I need to get some Torx sockets to undo the shift bracket. Once I have done that, and the opportunity arises to attack the beast, I'll let you know how I go!

(which should be sometime this week)

Thanks again

There are theories as to why GM used the thread locker on the drain plug but it has caused many people to round the head off. The shifter bracket is not that bad once you realize where the two torx bolts are.

I flushed mine at home using the Amsoil instructions.

Summary:

1) Drop pan and change fluid and filter

2) Refill with approx 5 qts of new fluid

3) Remove line and add extension hose and place end in a clear container

4) Have someone start the truck and fill the container. Make sure they are watching you to know when to kill it. Pump a qt out at a time.

5) Add a qt.

6) Pump out another qt.

You will do this about 10 times until you see the fluid running clean. You will notice it to begin to change color about the 4th or 5th qt you pump out.

Hope you can get that drain plug out. Be sure to have a new one on hand to replace it.

tomo62 · June 22, 2008

Thanks to C & A's Dad for his informative response.

Finished doing the fuel pump replacement in the Yukon beast and thought I would finish the trans whilst it's "legs where still in the air"

I don't know about the rest of the home mechanics out there - but I often find getting the car jacked up and on stands one of the hardest parts of any job in your garage...

Anyway, used all my mongrel cunning to get the air-gun and impact socket to jam onto the head of the nut to spin it off - but to no avail. As soon as I could say 'crap' the edges were neatly rounded from the transmisson sump plug...

If you need to drop the pan to drain the tranny - get a raincoat and some goggles, as as C&A's Dad said, take the bolts out and try let one corner droop and catch it at that point. It works, but so does the goggles, raincoat and a heap of flattened cardboard.

Taking off the shift bracket 'isn't the end of the world' if you have a #40 Torx key/socket handy - don't start without it!

The trans filter yanks right out - pity about the seal though. Suppose you can get a special puller from somewhere for this? If they just gave a small notch on the leading edge of the bore that the seal fits in - you could collapse the seal easily with a punch & hammer and peel it out simply. Lucky I found an edge of the seal housing and used that to cave it in, and peel it out.

The replacement filter I used was a Fram, and another good idea is that the holes in each corner of the filter are a little smaller and grab the pan bolts - so you can get the pan and gasket into position without the gasket coming dislodged.

I didn't do the full flush as outlined by Amsol and recommended by C&A's Dad. Might do a partial dump and refill later in the week to get rid of the remaiing 'green oil' from the torque converter.

And the sump / Pan plug?

To get it out - took the pan off and cleaned it thouroughly - then plug welded an oversized nut on the top. I just found a nut big enough to get the welding stick thru (3/4" AF) and did a plug weld to bond the plug and nut together. The plug came out easily once it was heated by the welding and given some torque thru the big nut. Quenched the plug quick so as not to burn the rubberr gasket. Was going to replace the nut when my buddy said 'why bother!' the big nut is perfect.

And then it was time for a beer...

Thanks C&As DAD!

Tomo62