Hello everyone. Working on resealing the two front blade angle cylinders on my D4H (Ser# 9GJ01015) and while doing the second one I discovered that the spring for the piston relief valve is broken. I want to replace the spring while I have it apart, but I can't figure out how to get the relief valve out of the piston. It appears to me that the small cylinder on the one side probably has to come out some how, but I don't know if it's threaded in or just press fit in. Does anyone know how to get this apart so I can replace the spring? Thanks in advance. T
Not threaded. Effectively it's all held in place by the washer #2. Get a brass drift and drive the plunger 6C right to left in the illustration. Having been in there for a long time the Spacer 6E may be a bit tight.
Thanks Nige. I was hitting on it with a drift punch but was afraid to hit it too hard for fear of damaging it. Will use a brass drift instead.
Hitting on it pretty good but still no movement. Even tried a little heat to see if that would break the plug loose but that didn’t work either. Any more ideas? Try it in a press maybe?
I reckon that spacer 6E will be in there tight. New 100-4529 piston is available with it already installed if all else fails. Not exactly cheap though.
I was about to mention that I've seen cases where we had to fit a new piston after failing to get that valve out. Maybe try putting it in a hydraulic press to pop the spacer out.? Below is taken from the D&A of a larger cylinder than yours but with the same valve setup x 3 in the piston. If necessary, use a press and push the plungers and inserts (8) out of piston (5).
Thanks for the replies gentlemen. She’s really stuck in there. Tried the press then tried putting some heat to it while it was in the press. Still a no go. At $650 or so for a new piston I think I’m just going to leave it alone. I really never noticed any problem with angling the blade and I imagine the worst it will do is bleed some pressure off that cylinder internally when it’s not at full extension or compression when it shouldn’t.
Yeah, but now that you f-ed with it............. Joe H
Hopefully I’m no worse off than I was when I took it apart to do the seals. The valve rods still seem to move the same as they did when I started.
I wanted to post an update to this thread in case someone with an old dozer like mine stumbles across it while doing their angle cylinders and is having trouble trying to get their piston apart to replace a broken spring. My OCD would not allow me to put the piston with the bad spring back in the cylinder since I will be selling this dozer when I'm done using it for my projects. I wasted several weeks ordering aftermarket pistons from a few different sources including eBay and Amazon and some other place, only to find out each time after ordering (and wasting a few days thinking it was on the way to me) that each place did not have the piston in stock and had no idea when any would come in. I did not want to spend $600+ on a new Cat piston but I did discover that Cat offered one of their Yellowmark parts for $350 or so. Feeling like I had nothing to lose anyway I got a little more aggressive with my efforts to get the original piston apart. I spent several hours working on it. I won't bore you with the details, but I'll sum it by saying I got it apart only to find out that one of the four parts I needed to rebuild my original piston (Cat calls it a spacer but really it's the sleeve that holds the valves and spring into the piston) is no longer available from Cat., I could not find an aftermarket source for that part either. The other three parts 2-valve rods and 1-spring are still available from Cat if you are somehow lucky enough to get your piston apart without destroying the "spacer". In my case I ended up having to order the Yellowmark part from Cat. Good luck to you if you are resealing your angle cylinders and find out that the relief valves are bad. T