Copper Sealing Washer HA237 for #643 #644 YS4C-63~70 OS4C-70~81 Hatroi  [HA237]

Sealing washer designed for RC glow engines

The HA237 copper gasket from Hatroi is an aftermarket replacement sealing washer intended for the engine identifiers listed in the product title. It serves as a simple spare part to re-establish a reliable seal between mating engine surfaces during routine service or full rebuilds.

Its mechanical purpose is to occupy small surface imperfections at the head-block interface, helping to preserve compression and to limit external leakage that can appear after disassembly or extended running. Always check the exact engine codes given in the product name to confirm correct part selection.

Installation guidance: clean both mating surfaces thoroughly and remove any remaining gasket remnants, place the copper gasket flat and centred, then assemble components and tighten to the manufacturer's recommended pattern and torque. Avoid overtightening, run the engine gently to check for leaks, and re-torque after the engine reaches normal temperature.

When troubleshooting reduced compression, fitting a new or reshaped copper gasket such as the HA237 is a standard diagnostic and repair step to determine whether sealing failure is the cause rather than internal mechanical wear.