TOOL

087 853 38 PUNCH is a critical guide bushing, often found deep inside the feed cylinder assembly on many of these rigs. Its main job is to keep the piston rod perfectly centered and moving true, taking all the side loads. This prevents the rod from rubbing against the cylinder wall, which would cause scoring and premature seal failure. Essentially, it ensures a smooth, consistent stroke and keeps the whole feed mechanism from binding up under pressure.

When this bushing starts to wear out, you’ll definitely notice it. The most common symptom is a bit of slop or play in the feed rod itself. That smooth, controlled movement becomes jerky, or you might start hearing a distinct knocking sound coming from the cylinder as the rod shifts around. Sometimes, the feed pressure can even fluctuate slightly because the rod isn't moving cleanly. If you pull the cylinder apart and see scoring marks on the piston rod, especially near the gland, that’s a pretty clear sign this bushing has seen better days and needs replacing pronto.

When you're swapping one of these out, take your time. First off, make sure the bore it sits in is absolutely clean; any old crud left behind will just chew up the new bushing in no time. And here’s a common oversight: always give the piston rod a good once-over for any burrs, nicks, or scoring. If the rod itself is damaged, that new bushing isn't going to last, and you'll be doing this job again way too soon. A little bit of the right assembly grease on the new bushing helps it seat properly and gives it a fighting chance from the get-go.