Hip squaking and rumbling after climbing

[JJC]

RHR 2010, LHR 2020, both Birmingham hips with DR Su.
57 yo male, rock climber since 1990.  I have well functioning hips for most routine activities.
I am a passionate climber, but find that whenever I climb hard, particularly with high stepping or other moves that require deep hip flexion, I develop symptoms within minutes to hours after the activity.
At worst, there is pain and squeaking. Occasionally the symptoms are more mild with no pain or squeak, but a "rumbling" sensation where I can feel the MOM components moving on each other.
These symptoms resolve within 1-2 days, with vigorous hydration.

I assume the symptoms are related to loss of synovial fluid in the joint with deep flexion motion.
I make sure to hydrate well before climbing.  This helps, but does not fix the problem.

Any other climbers have these issues?
Thoughts on how to prevent this? 
My hip mobility is not great.  Not sure if that is part of the problem

[stevel]

I had squeaking during hiking steep slopes when hunting or when “skinning” or hiking uphill with skis for about 3 years after my RBHR.  The squeaks would occasionally occur after a couple hours of hiking.  I thought squeaking was due to a combination of breaking in the soft tissue around my RBHR and hydration.  Last week I climbed steep slopes, sometimes in the snow, for 4 separate days (with a days rest in between) with no issues.  I have good flexibility.  I swim laps at the pool often when I’m not skiing or hunting.  I try to stay hydrated but a couple times the hydration bag leaked empty but I didn’t have any squeaking.