4L80E transmission cooling line bypass valve

[Will L.]

4L80E transmission cooling line bypass valve is a part all hmmwv and civilian Hummer, Hummer H1 have (idk about H2, H3).

On hummernetworkforum.com the discussion about this valve came up. I never noticed it on any GM rigs, or anything that the 4L80E went into outside of a hmmwv/Hummer. It’s possible that because I never had to replace one I simply never paid attention. I saw it on my Hummer, read about it and forgot about it basically.

The running theory is that when temps are so low the atf is thick and not flowing well so this device was added for extremely cold environments or maybe if a cooling line gets piched off roading and restricts flow- then this bypass valve simply sends the hot output atf directly back into the transmission as to not burn up the transmission right away. Better hot fluid than no fluid.

If anyone can find any vehicle this is on besides a hmmwv/ Hummer: please share the vehicle info, part number, LOVE PICS always, etc to teach me and others.

The two lines on this are simply spliced into a “T” that is interrupting the two cooler lines within about a foot of leaving the transmission.
Just because he isn’t on here as often as before, gonna bother @THEFERMANATOR for the extensive trans knowledge.

 

[denata]

A bypass valve is used in all Hummer vehicles (Figure 5-32).
The valve limits pressure buildup in the oil cooler and
lines.The bypass valve is attached to the passenger side cross-
member-to-frame bracket bolt. The cooler lines are attached to
body/chassis components with clamps (Figure 5-31).

 

[ak diesel driver]

Alot of trans coolers are set up with a type of bypass in that the passages are designed to flow and bypass when cold and as the fluid warms up it can flow through the smaller passages