Intro - First Offical Post (Recent replaced 98 Yukon with a 17)

[RobH]

The original issue transmission thermal bypass valve (thermostat) for the MYC (6l80E) and MYD (6L90E) transmissions maintains the transmission fluid at around 185F. The Service Bulletin No.: 21-NA-199 (search online for the current version) calls for installing a 70C/158F Thermal Bypass Valve to keep the transmission cooler. You may not have one of these two six speed transmissions.

 

[RobH]

Further to my last, there should be a SERVICE PARTS IDENTIFICATION (SPID) sticker

on your glove box door. It lists the three character codes for Factory installed equipment. The code for the 6L80E transmission is MYC.

6 speeds
L Longitudinal/RWD orientation
80 - power handling rating
E - controlled by Electronic Control Module.

You can take your VIN to a GM dealership parts counter and get a listing of what all the three character codes mean.

Thank you for your service. Rob H

 

[Fless]

The code for the 6L80E transmission is MCY.

MCY? Or MYC?

 

[RobH]

MCY? Or MYC?

You may have caught me in the midst of correcting my error. Thank you. The correct code for the 6L80E is MYC. MYC, darn it. My fingers like to mis-type the characters.

MYC like on my SPID picture above. ^^^

 

[Art Contoni]

Replaced the Antenna Amplifier and made no difference at all...

 

[Art Contoni]

Went ahead and installed the Superior Solutions Themal Bypass - will report temps later when I tow in Mid May. I'm at 149K so think I'm going to change Fluid and Filter again when it warm this Spring (we are still in the 30s).

 

[Art Contoni]

Been wanting to do this ever since my first oil change and spilling oil on the valve cover. Last weekends spillage was the final straw.

Oil Filler Tube - GM (12691785) (stock on 2019-2026 5.3s and 6.2s)

Good how to here: https://youtube.com/shorts/0RuGBZOizoc?si=X6cPui0ZfjwmiIZn although I couldn't get the tab to release correctly and broke it off. Shined a flash light straight down inside the head and was able to retrieve it with finger claw tool.

Instead of trimming the fill tube gusset I used a cut off tool to trim the valve cover insulator cover (would need to be able to come off if you ever have to service the valve cover gaskets).

Also highly recommend this Funnel from MOTIV Tools, they make other ends that screw on the blue funnel. I have one for the Daughters Camry. It quarter turn locks in the tube like the fill cap.

 

[JoeBlobs]

Been wanting to do this ever since my first oil change and spilling oil on the valve cover. Last weekends spillage was the final straw.

Oil Filler Tube - GM (12691785) (stock on 2019-2026 5.3s and 6.2s)

Good how to here: https://youtube.com/shorts/0RuGBZOizoc?si=X6cPui0ZfjwmiIZn although I couldn't get the tab to release correctly and broke it off. Shined a flash light straight down inside the head and was able to retrieve it with finger claw tool.

Instead of trimming the fill tube gusset I used a cut off tool to trim the valve cover insulator cover (would need to be able to come off if you ever have to service the valve cover gaskets).

Also highly recommend this Funnel from MOTIV Tools, they make other ends that screw on the blue funnel. I have one for the Daughters Camry. It quarter turn locks in the tube like the fill cap.

Great QOL mod! How's the truck been holding up, and how's she lookin' nowadays?

 

[Art Contoni]

Joe,

I'm now at 156K miles and have had some minor maintenance issues.

I think I either got counter fit or a bad set of AC Delco Plugs and had to replace them all again about a year ago. Was getting misfire codes over a period of time.

A few weeks ago we heard a strange pop and a check engine light come on during a trip and accelerating from a rest stop on ramp while pulling a light trailer.

Ended being a cracked RH exhaust manifold and two broken bolts.

Its also begin to pop a little rust under the paint above the driver side rear fender well. My Mrs 2013 Tahoe is also doing it.

Still have not resolved the crappy radio reception