The Coquihalla climbs do not themselves cause failures, rather it exposes
the weaknesses of the 4L60e design. Torque converter clutch slip is the most
likely cause of your trucks tranny fluid boil-off . The valve body issues
(leakage) allowed the clutch slip with no coolers capable of dealing with
the resultant heat!
Did you tackle this climb in OD?
This climb equates to towing at max gross weight with max frontal area of
trailer in tow whilst pushing a 60 MPH head wind in Gary's neck of the
The Mighty Coqu demands respect: it has mine! Mighty Semi Tractor units meet
their match here.
This ought to be GM's severe duty test track! There are no equals anywhere
else as this is where I see 260*f temps at cooler inlet on my Suburban
loaded to max with family and tent trailer behind.
Climb in 3rd with speeds between 85-90 Km/h also 18L/100km (14 MPG).We may
be passed by almost everything but we'll pass anything that has failed to
respect the Mighty Coquihalla.
You're beyond Hope if you need the tow back to Hope BC
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