15-3520-52 is the Buna-N center block gasket on the Wilden T15. Cheap, easy to overlook, and often blamed on other parts when it leaks.
| Material | Buna-N (nitrile rubber) |
|---|
Part 15-3520-52 is the Buna-N gasket that seals the T15’s center block joint — a solid general-purpose rubber with decent resistance to petroleum-based fluids and oils, a reasonable temperature range, and a lower price tag than higher-spec elastomers like Viton.
A slow air leak right at that joint tends to get blamed on the air valve or the shaft seal far more often than it gets blamed on the gasket sitting directly at the seam. Checking the obvious spot first can save a lot of time before chasing something more complicated.
Buna-N isn’t the right call for every fluid: strong acids, certain solvents and ozone exposure degrade it faster than normal wear would, so it pays to check your fluid list against a compatibility chart instead of reordering the same material out of habit. And because this gasket sits on a static joint rather than a moving part, it ages slowly — if a center block is already open for other work, swapping the gasket while it’s apart is cheap enough that there’s rarely a reason to skip it.
A center block rebuild at this point is also a natural time to check the diaphragm — it’s usually due for inspection on the same schedule.
Genuine Wilden AODD Diaphragm Pumps & Spare Parts15-3210-55-225 is the PTFE Glyd Ring sealing the T15’s shaft at the center block. A high-wear part on any pump running heavy duty cycles.
Genuine Wilden AODD Diaphragm Pumps & Spare Parts15-6850-08 is the inner piston back-up washer on the Wilden T15 (position 18), made from mild steel — small, cheap, and easy to skip by mistake.
Genuine Wilden AODD Diaphragm Pumps & Spare Parts15-3100-01-225 is the aluminum center block on the Wilden T15 — the hub that the air valve, shaft and both chambers all attach to.
