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tlaw91

8 speed fluid and filter change

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Ok here we go kids!

 

To start I use a quarter inch 10mm swivel socket a 5 in extension and a Milwaukee 1/4 drive ratchet.

 

This will require multiple posts due to photos.

 

First you unbolt the 10mm bolt that is for checking fluid level, let that drain as much as possible.

 

 While that’s draining take off the heat shield in the right side of the trans. There’s one ten mm on the side, and two at the top. I usually throw my ratchet up there and get them that way, you may find it easier to use a wrench or something.

 

You’ll see a rubber fill plug after removing the heat shield, go ahead and remove that by pushing the top part of the plug up with a flag screwdriver then pulling up.

7079cb5f35db338cff35329b2bca535e.jpg

 

 

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Next we move on to unbolting the pan. Start at the bolts at the front of the transmission and take them off evenly until you get to the last bolt at the back. You’re about to make a mess.

I hold the pan up with one hand and remove the last bolt with another. Then you can as slowly as possible let the pan down until it looks like this

aed38bf72bd3484b093161f0d1e214d5.jpg

It’s a mess lol


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Ok now the tricky part but it saves a lot of time.

You are going to take a pick or screwdriver

This is my tool

3d0314ce463eac87c59a825ecee5cc7f.jpg

And undo the rear most two shift solenoids


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86240118f48bb6591485942103b5f367.jpg

 

You can see in the last transmission pic where they are disconnected.

 

With them connected there is not enough room to wiggle the pan out.

 

When you disconnect the solenoids it allows the pan to slide out.

 

Great! Move onto removing and discarding the filter and cleaning the pan magnets!

 

 

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b5740b206f8c53e489618b42e82138ba.jpg

Mmm clean.

Remember the transmission gasket is reusable!

Also be sure when installing the transmission filter you push it all the way into the transmission and the locator pin on the filter goes into the hole in the valve body correctly.

Next after filter install and cleaning you reinstall the pan with the gasket on it.

Put the pan in the same fallen position as before, reach up there with your pick or screwdrivers and reconnect the solenoids connectors. You can’t mix them up they only go into the connector they fit into. This can be tricky but you’ll get it.

After that install the pan with the 10 mm bolts. Torque spec is unimportant to me, I just max out the ratchet at around 20 ft lbs and never had an issue.

Now install the check plug you took out to drain some of the fluid.



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Now you’ll go ahead and begin filling the fluid.

This is what your transmission requires

bb4fd3293d0f453572cdce62e6042b42.jpg


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GM has a rather complicated procedure to check fluid level, you aren’t going to do any of that because you know it take 7.4 quarts to fill the transmission after a filter change.

Go ahead and install the fluid now in the fill plug hole. I use a machine at the shop and it looks like this

ef25406410caf904b50c13c024f61031.jpg


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After filling 7.4 quarts, install the rubber fill plug and the heat shield. Ok all done! At this time you’ve made a damn mess so I brake clean the exhaust pipe and transmission pan at this time.

And that is how you change the fluid and filter on your 8 speed transmission on your Sierra/Yukon without messing with the exhaust.

Ask any questions if my impromptu write up wasn’t thorough enough, I do this a lot so I may have missed a small step I do out of habit!

Hope this helps

-GM Technician




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341bc322210c64ae3dca9b03d8947ff4.jpg

Here’s another pic of the two connectors you need to disconnect


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Nice write up! Is the procedure essentially the same for a six speed?

No

Tomorrow if I remember I have to mock up a 6 speed pan removal.

Involves two blocks of wood and a jack


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You mention something about a locator pin on the filter when installing, but you did not explain how to remove the filter.  Can you elaborate a bit on filter removal and installation?  Also, I've read a few posts that say the pan can be removed without removing the exhaust (yours does too) but this is the first one I've read that say to  unplug solenoids to do it.  Is this a model specific requirement, or all Sierra/Silverado?

 

Sorry for the novice questions, but when it comes to automatic transmissions, I am not confident.  Rebuilding diffs or engine swaps are no problem, but the AT is a bit of a black box to me.

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No

Tomorrow if I remember I have to mock up a 6 speed pan removal.

Involves two blocks of wood and a jack


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My 6sp in my suburban was the first one my local guy did, he said it was a lot different than any he’d done before, they didn’t give any rooms in there, hence the block of wood and jack I presume


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