Turns out previous owner had gone righty tight enough a bolt on one of the lower relief valves until it went righty-loosey.. Mostly out of laziness, instead of taking all of the lines off, I cleaned off the outside as best I could in the field and loosened the through-bolts that hold the valves together as the one I needed to get to was 4th from the end. Got it off there and have that particular valve cleaned up and ready to roll. The question here is, there are some of the control valves that separated from one another and got a little gunk in there. That being said, is the opinion that I should remove every one of the 30+ hoses, all control valves and clean the hell out of them and reassemble everything? Or can I get away with some brake cleaner, compressed air, check it visibly and call it good enough? Keep in mind this is a homestead machine, not needing to be on a job making money every day. I feel like I know the answer is that these things need to be "inside of valve cover" clean, as the valve plunger/pin thing seems to be super tight tolerance, and wherever the hydraulic fluid goes after is to the cylinders and system itself... But just in the off case that these repairs are normally performed in field with a little dirt here and there and things go on working nevertheless.... I really dont want to mark and disconnect all of these hoses.
ISO 16/13. Pretty damn clean. But, your mileage may vary. So expensive. So time consuming. So, painful and time consuming.
Heeded your warning and just took the whole stack of valves out to clean and rebuild. There was just no way I was getting it back together without something messing up or trapping dirt inside. Anything regarding the valves is not cheap per cat's parts site... There are these 8x3mm plates that float in a shallow hole in most of the valve bodies (they're either seated at the base of the one valves hole, or pushed to the top and blocking a hole from the adjacent valve... Seems like I lost 3 of them. 26 a piece from cat but I have some 8mm stainless rod that I'll make some replacements out of. Anyone know what those are for?
The hole in question, normally with a 8x3mm "plate" that sits in it
If you can see crud, that's bad. Valve cover clean would be hydraulic system dirty. Calve cover us at 0psi... hydraulic system might see 3000-4000psi, or higher on some stuff. I've seen expensive equipment need very expensive repairs from trash going through. One was from a blown main pressure line that the new one wasn't clean. Had a bunch of rubber bits and probably dirt too. That stuff plugged valves, solenoids, etc that took dozens and dozens of man hours to sort out.