diff --git a/src/main/java/me/desht/pneumaticcraft/common/block/entity/AbstractAirHandlingBlockEntity.java b/src/main/java/me/desht/pneumaticcraft/common/block/entity/AbstractAirHandlingBlockEntity.java
index 5c9825721..98cdca170 100644
--- a/src/main/java/me/desht/pneumaticcraft/common/block/entity/AbstractAirHandlingBlockEntity.java
+++ b/src/main/java/me/desht/pneumaticcraft/common/block/entity/AbstractAirHandlingBlockEntity.java
@@ -120,7 +120,6 @@ private void handleSecurityUpgrade(IAirHandlerMachine handler) {
     public void onBlockRotated() {
         super.onBlockRotated();
 
-        // force a recalculation of where any possible leak might be coming from
         initializeHullAirHandlers();
 
         airHandlerMap.keySet().forEach(h -> h.setSideLeaking(null));
diff --git a/src/main/java/me/desht/pneumaticcraft/common/block/entity/tube/PressureTubeBlockEntity.java b/src/main/java/me/desht/pneumaticcraft/common/block/entity/tube/PressureTubeBlockEntity.java
index 6e7202fe7..f21ac1e0c 100644
--- a/src/main/java/me/desht/pneumaticcraft/common/block/entity/tube/PressureTubeBlockEntity.java
+++ b/src/main/java/me/desht/pneumaticcraft/common/block/entity/tube/PressureTubeBlockEntity.java
@@ -70,6 +70,7 @@ public class PressureTubeBlockEntity extends AbstractAirHandlingBlockEntity impl
     private final List<Direction> neighbourDirections = new ArrayList<>();
     private VoxelShape cachedTubeShape = null; // important for performance
     private int pendingCacheShapeClear = 0;
+    private boolean needDiscover = false;
 
     public PressureTubeBlockEntity(BlockPos pos, BlockState state) {
         this(ModBlockEntityTypes.PRESSURE_TUBE.get(), pos, state, PressureTier.TIER_ONE, PneumaticValues.VOLUME_PRESSURE_TUBE);
@@ -199,6 +200,11 @@ public void tickClient() {
     public void tickServer() {
         super.tickServer();
 
+        if (needDiscover) {
+            discoverConnectedNeighbors();
+            needDiscover = false;
+        }
+
         boolean couldLeak = true;
 
         for (Direction dir : DirectionUtil.VALUES) {
@@ -320,7 +326,10 @@ public void onNeighborBlockUpdate(BlockPos fromPos) {
 
         tubeModules().forEach(AbstractTubeModule::onNeighborBlockUpdate);
 
-        discoverConnectedNeighbors();
+        // connected neighbour discovery needs to be deferred,
+        //   since although the neighbouring block has updated,
+        //   the block entity's air handler data may not yet have updated
+        needDiscover = true;
     }
 
     private void discoverConnectedNeighbors() {
diff --git a/src/main/java/me/desht/pneumaticcraft/common/capabilities/MachineAirHandler.java b/src/main/java/me/desht/pneumaticcraft/common/capabilities/MachineAirHandler.java
index 0e264315a..f960eb8b0 100644
--- a/src/main/java/me/desht/pneumaticcraft/common/capabilities/MachineAirHandler.java
+++ b/src/main/java/me/desht/pneumaticcraft/common/capabilities/MachineAirHandler.java
@@ -119,11 +119,6 @@ public void disableSafetyVenting() {
     public void setConnectableFaces(Collection<Direction> sides) {
         connectableFaces.clear();
         sides.forEach(side -> connectableFaces.set(side.get3DDataValue()));
-
-        // invalidate cached neighbour data
-        for (Direction dir : DirectionUtil.VALUES) {
-            this.neighbourAirHandlers.put(dir, null);
-        }
     }
 
     @Override
@@ -248,9 +243,7 @@ private Optional<IAirHandlerMachine> getNeighbourAirHandler(BlockEntity ownerTE,
                 neighbourAirHandlers.put(dir, BlockCapabilityCache.create(PNCCapabilities.AIR_HANDLER_MACHINE,
                         level,
                         ownerTE.getBlockPos().relative(dir),
-                        dir.getOpposite(),
-                        () -> !ownerTE.isRemoved(),
-                        () -> neighbourAirHandlers.put(dir, null)
+                        dir.getOpposite()
                 ));
             }
             return Optional.ofNullable(neighbourAirHandlers.get(dir).getCapability());