Jim?!!? What's that popping sound?
This is what Melinda kept asking me, after owning our Bighorn for a little over a year. So, I did some research and found the solution was simple....if you know the trick.
Adding a quart of Cat Hydraulic Oil Additive (model # 1U-9891) stops sticky or noisy hydraulics and for us...it removed the popping noise. Score!! Just remember to take out a quart, before you add this quart in, or you might have a big mess on your hands.
How to purchase?
Do quick internet search. I found it on ebay for around $35, but I've heard of folks getting it for around $25. While not cheap by any mean for only a quart....it solved our "popping" noise on the first trip out with it installed.