There is a huge spring involved and no obvious way to get the tension off of it. Any help greatly appreciated.
Not sure how similar the D4C is to my D4D for the hyd adjuster, but on mine the spring stops hold the spring in place, enabling you to take the adjuster assembly out. Have any pictures of your set up? As many warn on this forum, be careful messing with the spring, as there is about 7 tons of force holding that spring in place.
I'm assuming your D4c is an older machine similar to the D4d above and not a late mode D4c. Best to get service info for your specific tractor to be sure you're following procedure correctly. (I tried looking up a diagram on Cat's parts site but they don't have online info for the old D4c) A couple of thing to consider: You should be able to remove the piston without removing the recoil spring but be sure the stops at the front of the spring are in good condition and it's not out of alignment, or worn so the spring it cocked. The plate at the front of the spring should have ears that hook under the spring stops.....check to be sure they are not broken or out of place. If the nut at the rear isn't rusted solid you can run it up until it is against the track frame bracket to act as a safety. The nut at the back of the spring is designed to hold the spring in compression for assembly only.....but....the nut and bolt are prone to rust and can fail if in poor condition. Quite a few mechanics won't trust old rusty ones to hold during disassembly, and will only take it apart by heating the spring to relieve the preload. Do not "guess" at what you're doing....be sure. That spring can come out of there like a bullet and kill you.
Thanks for the advice. I'll be getting someone who knows what they are doing.