8 speed fluid and filter change

[tlaw91 135]

Unplugging the solenoids is an 8 speed specific procedure done on Sierra/Yukon trucks and SUV’s

Great question about the filter

To remove, pull down.

Before installing please note a locator pin on top of the transmission filter. Now look up at the valve body. You will see an oblong hole located in the valve body in the center of it, this is where the locator pin goes.

Now you have an idea of this, go ahead and insert the neck of the filter into the transmission. Push up some until the locator tab gets aligned with the hole in the valve body. Now at this point I usually hit the filter up into the trans with a closed fist. It will be completely secure now and lined up, ready for the pan to be slid in.

Hope this was more specific


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[2018GMC 505]

Great writeup and pics!

 

When do you recommend first, second, etc service for the daily driven truck / suv with occasional weekend towing?

[Mike GMC 310]

I have always assumed Sierra and Silverado were the same underneath.  I have an 18 Silverado with an 8 speed/5.3L.  Will this be any different than the Sierra with the same trans/engine?  I have just over 20k on it and have been thinking I should do this service soon.  It all seems to work well now, but I want to keep it that way, not wait for an issue.

Edited February 7, 2020 by Mike GMC

[tlaw91 135]

I have always assumed Sierra and Silverado were the same underneath.  I have an 18 Silverado with an 8 speed/5.3L.  Will this be any different than the Sierra with the same trans/engine?  I have just over 20k on it and have been thinking I should do this service soon.  It all seems to work well now, but I want to keep it that way, not wait for an issue.

Exact same truck.

45k intervals will serve you and your truck well.


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[mookdoc6 785]

56 minutes ago, tlaw91 said:

Exact same truck.

45k intervals will serve you and your truck well.


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Very Nice Son!  I was one of the first 8 speeds my Trans shop seen when they came out.  The 8 speeds are finicky and like to be HOT and Torqued out...the more the better.  I agree about the flush it's a must and 45K is probably right on the money with the 8speeds they need routine flushes imo.  

[JimCost2014 1,477]

1 hour ago, tlaw91 said:

Unplugging the solenoids is an 8 speed specific procedure done on Sierra/Yukon trucks and SUV’s

Great question about the filter

To remove, pull down.

Before installing please note a locator pin on top of the transmission filter. Now look up at the valve body. You will see an oblong hole located in the valve body in the center of it, this is where the locator pin goes.

Now you have an idea of this, go ahead and insert the neck of the filter into the transmission. Push up some until the locator tab gets aligned with the hole in the valve body. Now at this point I usually hit the filter up into the trans with a closed fist. It will be completely secure now and lined up, ready for the pan to be slid in.

Hope this was more specific


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So, what are your feelings on the "flushes" that most dealers offer?

 

Better to get all of the fluid, or most of it with a drain?

 

How much debris is in the filter at 45000 miles? And do all of the trucks have filters in them? Different stories about what members are being told about them.

[tlaw91 135]

So, what are your feelings on the "flushes" that most dealers offer?
 
Better to get all of the fluid, or most of it with a drain?
 
How much debris is in the filter at 45000 miles? And do all of the trucks have filters in them? Different stories about what members are being told about them.

All trucks have transmission filters

If you are to do this procedure as I described then you will be removing 7.4 quarts

This procedure is for the DIY-er, if you were to have the dealership do this service they would be doing exactly how you see it here.

Hope this helps




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[RE1 79]

Great posts, man. Thank you. 

[JimCost2014 1,477]

4 hours ago, tlaw91 said:

All trucks have transmission filters

If you are to do this procedure as I described then you will be removing 7.4 quarts

This procedure is for the DIY-er, if you were to have the dealership do this service they would be doing exactly how you see it here.

Hope this helps




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I was talking about when you hook up the machine to the cooler lines and flush the system, pushing out the old fluid with new, not changing the filter or dropping the pan.

[mookdoc6 785]

17 minutes ago, JimCost2014 said:

I was talking about when you hook up the machine to the cooler lines and flush the system, pushing out the old fluid with new, not changing the filter or dropping the pan.

Correct, I have this service done and it's 13qts even though it supposed to be 12.7 or something.

[JimCost2014 1,477]

3 minutes ago, mookdoc6 said:

Correct, I have this service done and it's 13qts even though it supposed to be 12.7 or something.

Any problems since you have had it done?

 

Seems like most on here do not like this method. We had our Tahoe done this way and everything seems to be just fine afterwards.

Edited February 7, 2020 by JimCost2014

[tlaw91 135]

I was talking about when you hook up the machine to the cooler lines and flush the system, pushing out the old fluid with new, not changing the filter or dropping the pan.

You should not do this on the 8 speed transmission.

It has an internal valve that closes the inlet port when the temp isn’t hot enough

So you run the risk of running your transmission dry, trans fluid can leave the outlet all day but if it’s not hot enough the internal valve shuts and won’t let you fill it.

Drain and fill your 8 speeds.


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[JimCost2014 1,477]

22 minutes ago, tlaw91 said:

You should not do this on the 8 speed transmission.

It has an internal valve that closes the inlet port when the temp isn’t hot enough

So you run the risk of running your transmission dry, trans fluid can leave the outlet all day but if it’s not hot enough the internal valve shuts and won’t let you fill it.

Drain and fill your 8 speeds.


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How about the 6 speeds?

 

Ok for them?

 

Does your dealership perform this type of service?

[mookdoc6 785]

3 hours ago, tlaw91 said:

You should not do this on the 8 speed transmission.

It has an internal valve that closes the inlet port when the temp isn’t hot enough

So you run the risk of running your transmission dry, trans fluid can leave the outlet all day but if it’s not hot enough the internal valve shuts and won’t let you fill it.

Drain and fill your 8 speeds.


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requires the use of the DT-45096 TransFlow Cooler Flush Machine and DT-52263 Transmission Fluid Exchange Tool Kit

 

I am confused?  My service dept. uses this?  Pretty much all the coolant comes out and is brought back into the system via the Trans Pump?  This is a complete replacement.  Cooler is flushed too?  Are you using this system?  Thanks

[tlaw91 135]

requires the use of the DT-45096 TransFlow Cooler Flush Machine and DT-52263 Transmission Fluid Exchange Tool Kit
 
I am confused?  My service dept. uses this?  Pretty much all the coolant comes out and is brought back into the system via the Trans Pump?  This is a complete replacement.  Cooler is flushed too?  Are you using this system?  Thanks

We drain and fill.

Yeah I know what you’re talking about though


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