diff --git a/changelog.d/3932.bugfix b/changelog.d/3932.bugfix
new file mode 100644
index 0000000000000000000000000000000000000000..7578414ede72ca5b716725e723510aa6be89f52a
--- /dev/null
+++ b/changelog.d/3932.bugfix
@@ -0,0 +1 @@
+Fix some instances of ExpiringCache not expiring cache items
diff --git a/synapse/app/appservice.py b/synapse/app/appservice.py
index 86b5067400e3d572831737ccebe85cd34645737f..02039f7e793ccd3eddf2984b45fb844f040c9741 100644
--- a/synapse/app/appservice.py
+++ b/synapse/app/appservice.py
@@ -172,7 +172,6 @@ def start(config_options):
 
     def start():
         ps.get_datastore().start_profiling()
-        ps.get_state_handler().start_caching()
 
     reactor.callWhenRunning(start)
 
diff --git a/synapse/app/client_reader.py b/synapse/app/client_reader.py
index ce2b113dbb975fb7c1ea2cf4c8a84f34967fb871..4c73c637bb71e63f9960e97b43076b5954daca3a 100644
--- a/synapse/app/client_reader.py
+++ b/synapse/app/client_reader.py
@@ -181,7 +181,6 @@ def start(config_options):
     ss.start_listening(config.worker_listeners)
 
     def start():
-        ss.get_state_handler().start_caching()
         ss.get_datastore().start_profiling()
 
     reactor.callWhenRunning(start)
diff --git a/synapse/app/event_creator.py b/synapse/app/event_creator.py
index f98e456ea0b56c75a4267176cf12b0cb0021dbee..bc82197b2a83fb13e4e0cc51282b3738d1d58190 100644
--- a/synapse/app/event_creator.py
+++ b/synapse/app/event_creator.py
@@ -199,7 +199,6 @@ def start(config_options):
     ss.start_listening(config.worker_listeners)
 
     def start():
-        ss.get_state_handler().start_caching()
         ss.get_datastore().start_profiling()
 
     reactor.callWhenRunning(start)
diff --git a/synapse/app/federation_reader.py b/synapse/app/federation_reader.py
index 60f597350501e608d3f2168a07a818b8a0e31330..18ca71ef99e8248da01a1153aab74e7ca5850400 100644
--- a/synapse/app/federation_reader.py
+++ b/synapse/app/federation_reader.py
@@ -168,7 +168,6 @@ def start(config_options):
     ss.start_listening(config.worker_listeners)
 
     def start():
-        ss.get_state_handler().start_caching()
         ss.get_datastore().start_profiling()
 
     reactor.callWhenRunning(start)
diff --git a/synapse/app/federation_sender.py b/synapse/app/federation_sender.py
index 60dd09aac30cad75b30711e8db7f60bd2f00412d..6501c577923067cbce5f1a693033de0a141561ce 100644
--- a/synapse/app/federation_sender.py
+++ b/synapse/app/federation_sender.py
@@ -201,7 +201,6 @@ def start(config_options):
 
     def start():
         ps.get_datastore().start_profiling()
-        ps.get_state_handler().start_caching()
 
     reactor.callWhenRunning(start)
     _base.start_worker_reactor("synapse-federation-sender", config)
diff --git a/synapse/app/frontend_proxy.py b/synapse/app/frontend_proxy.py
index 8c0b9c67b07f287e9a5514ad6ff5f01b48471e32..b076fbe522b0a340226f6ef23c9a009d1a2bffa7 100644
--- a/synapse/app/frontend_proxy.py
+++ b/synapse/app/frontend_proxy.py
@@ -258,7 +258,6 @@ def start(config_options):
     ss.start_listening(config.worker_listeners)
 
     def start():
-        ss.get_state_handler().start_caching()
         ss.get_datastore().start_profiling()
 
     reactor.callWhenRunning(start)
diff --git a/synapse/app/homeserver.py b/synapse/app/homeserver.py
index 3241ded1889fd5c4f7aa0f70187a84b46768b25f..8c5d858b0b650323d22c6b1cd94485171fd673cf 100755
--- a/synapse/app/homeserver.py
+++ b/synapse/app/homeserver.py
@@ -384,7 +384,6 @@ def setup(config_options):
 
     def start():
         hs.get_pusherpool().start()
-        hs.get_state_handler().start_caching()
         hs.get_datastore().start_profiling()
         hs.get_datastore().start_doing_background_updates()
         hs.get_federation_client().start_get_pdu_cache()
diff --git a/synapse/app/media_repository.py b/synapse/app/media_repository.py
index e3dbb3b4e6bb1599b34d4cc4027889381c5e9daf..992d182dba42ef01ef4ed943d702902a2b1561e8 100644
--- a/synapse/app/media_repository.py
+++ b/synapse/app/media_repository.py
@@ -168,7 +168,6 @@ def start(config_options):
     ss.start_listening(config.worker_listeners)
 
     def start():
-        ss.get_state_handler().start_caching()
         ss.get_datastore().start_profiling()
 
     reactor.callWhenRunning(start)
diff --git a/synapse/app/pusher.py b/synapse/app/pusher.py
index 244c604de91c7f2af9e1a2e86c872c1cf28bd9b2..2ec4c7defb98a10232267e8352000d8384992f56 100644
--- a/synapse/app/pusher.py
+++ b/synapse/app/pusher.py
@@ -228,7 +228,6 @@ def start(config_options):
     def start():
         ps.get_pusherpool().start()
         ps.get_datastore().start_profiling()
-        ps.get_state_handler().start_caching()
 
     reactor.callWhenRunning(start)
 
diff --git a/synapse/app/synchrotron.py b/synapse/app/synchrotron.py
index 6662340797dcd8c33821a0412c8e688704758666..df81b7bcbe11542ffc1f330d64ee19c3ecbbd2f1 100644
--- a/synapse/app/synchrotron.py
+++ b/synapse/app/synchrotron.py
@@ -435,7 +435,6 @@ def start(config_options):
 
     def start():
         ss.get_datastore().start_profiling()
-        ss.get_state_handler().start_caching()
 
     reactor.callWhenRunning(start)
 
diff --git a/synapse/app/user_dir.py b/synapse/app/user_dir.py
index 96ffcaf073d4a108408c5fe2312f8b7a961997d7..b383e79c1ccd0b3370ca5f18b7fcf8308ff4be45 100644
--- a/synapse/app/user_dir.py
+++ b/synapse/app/user_dir.py
@@ -229,7 +229,6 @@ def start(config_options):
 
     def start():
         ps.get_datastore().start_profiling()
-        ps.get_state_handler().start_caching()
 
     reactor.callWhenRunning(start)
 
diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index fe67b2ff42a9573f2793c78753c657e108a7e1e2..5a92428f56c2e25c7b519e385deff689c1739c92 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -66,6 +66,14 @@ class FederationClient(FederationBase):
         self.state = hs.get_state_handler()
         self.transport_layer = hs.get_federation_transport_client()
 
+        self._get_pdu_cache = ExpiringCache(
+            cache_name="get_pdu_cache",
+            clock=self._clock,
+            max_len=1000,
+            expiry_ms=120 * 1000,
+            reset_expiry_on_get=False,
+        )
+
     def _clear_tried_cache(self):
         """Clear pdu_destination_tried cache"""
         now = self._clock.time_msec()
@@ -82,17 +90,6 @@ class FederationClient(FederationBase):
             if destination_dict:
                 self.pdu_destination_tried[event_id] = destination_dict
 
-    def start_get_pdu_cache(self):
-        self._get_pdu_cache = ExpiringCache(
-            cache_name="get_pdu_cache",
-            clock=self._clock,
-            max_len=1000,
-            expiry_ms=120 * 1000,
-            reset_expiry_on_get=False,
-        )
-
-        self._get_pdu_cache.start()
-
     @log_function
     def make_query(self, destination, query_type, args,
                    retry_on_dns_fail=False, ignore_backoff=False):
@@ -229,10 +226,9 @@ class FederationClient(FederationBase):
 
         # TODO: Rate limit the number of times we try and get the same event.
 
-        if self._get_pdu_cache:
-            ev = self._get_pdu_cache.get(event_id)
-            if ev:
-                defer.returnValue(ev)
+        ev = self._get_pdu_cache.get(event_id)
+        if ev:
+            defer.returnValue(ev)
 
         pdu_attempts = self.pdu_destination_tried.setdefault(event_id, {})
 
@@ -285,7 +281,7 @@ class FederationClient(FederationBase):
                 )
                 continue
 
-        if self._get_pdu_cache is not None and signed_pdu:
+        if signed_pdu:
             self._get_pdu_cache[event_id] = signed_pdu
 
         defer.returnValue(signed_pdu)
diff --git a/synapse/rest/media/v1/preview_url_resource.py b/synapse/rest/media/v1/preview_url_resource.py
index cad2dec33a2b57720a6604dce83abb82c2ff6335..af01040a38da2160131836c3eefac1ef570e86f7 100644
--- a/synapse/rest/media/v1/preview_url_resource.py
+++ b/synapse/rest/media/v1/preview_url_resource.py
@@ -79,7 +79,6 @@ class PreviewUrlResource(Resource):
             # don't spider URLs more often than once an hour
             expiry_ms=60 * 60 * 1000,
         )
-        self._cache.start()
 
         self._cleaner_loop = self.clock.looping_call(
             self._start_expire_url_cache_data, 10 * 1000,
diff --git a/synapse/state/__init__.py b/synapse/state/__init__.py
index d7ae22a661f6e66315177f5ac326af3b227dbe5f..b22495c1f974503cc2dcb1c1a09c1a2d8caca660 100644
--- a/synapse/state/__init__.py
+++ b/synapse/state/__init__.py
@@ -95,10 +95,6 @@ class StateHandler(object):
         self.hs = hs
         self._state_resolution_handler = hs.get_state_resolution_handler()
 
-    def start_caching(self):
-        # TODO: remove this shim
-        self._state_resolution_handler.start_caching()
-
     @defer.inlineCallbacks
     def get_current_state(self, room_id, event_type=None, state_key="",
                           latest_event_ids=None):
@@ -428,9 +424,6 @@ class StateResolutionHandler(object):
         self._state_cache = None
         self.resolve_linearizer = Linearizer(name="state_resolve_lock")
 
-    def start_caching(self):
-        logger.debug("start_caching")
-
         self._state_cache = ExpiringCache(
             cache_name="state_cache",
             clock=self.clock,
@@ -440,8 +433,6 @@ class StateResolutionHandler(object):
             reset_expiry_on_get=True,
         )
 
-        self._state_cache.start()
-
     @defer.inlineCallbacks
     @log_function
     def resolve_state_groups(
diff --git a/synapse/util/caches/expiringcache.py b/synapse/util/caches/expiringcache.py
index ce85b2ae1179584ecfed226bb9879b4cdf1c55d3..921a9c5b29a50a888bee3d0a9ed8cff7417d0772 100644
--- a/synapse/util/caches/expiringcache.py
+++ b/synapse/util/caches/expiringcache.py
@@ -58,7 +58,6 @@ class ExpiringCache(object):
 
         self.metrics = register_cache("expiring", cache_name, self)
 
-    def start(self):
         if not self._expiry_ms:
             # Don't bother starting the loop if things never expire
             return
diff --git a/tests/util/test_expiring_cache.py b/tests/util/test_expiring_cache.py
index 5cbada4edaff830264065408c6c24af7086fdde8..50bc7702d20be00c1741757dd52fff0d0427b051 100644
--- a/tests/util/test_expiring_cache.py
+++ b/tests/util/test_expiring_cache.py
@@ -65,7 +65,6 @@ class ExpiringCacheTestCase(unittest.TestCase):
     def test_time_eviction(self):
         clock = MockClock()
         cache = ExpiringCache("test", clock, expiry_ms=1000)
-        cache.start()
 
         cache["key"] = 1
         clock.advance_time(0.5)