diff --git a/pymongo/operations.py b/pymongo/operations.py
index 58655753b..4872afa91 100644
--- a/pymongo/operations.py
+++ b/pymongo/operations.py
@@ -592,7 +592,7 @@ class SearchIndexModel:
         self,
         definition: Mapping[str, Any],
         name: Optional[str] = None,
-        type: Optional[str] = "search",
+        type: Optional[str] = None,
         **kwargs: Any,
     ) -> None:
         """Create a Search Index instance.
@@ -613,7 +613,8 @@ class SearchIndexModel:
         if name is not None:
             self.__document["name"] = name
         self.__document["definition"] = definition
-        self.__document["type"] = type
+        if type is not None:
+            self.__document["type"] = type
         self.__document.update(kwargs)
 
     @property
diff --git a/test/test_index_management.py b/test/test_index_management.py
index c47cffa75..5b6653dcb 100644
--- a/test/test_index_management.py
+++ b/test/test_index_management.py
@@ -62,7 +62,17 @@ class TestCreateSearchIndex(IntegrationTest):
         listener.reset()
         with self.assertRaises(OperationFailure):
             coll.create_search_index({"definition": definition, "arbitraryOption": 1})
-        self.assertIn("arbitraryOption", listener.events[0].command["indexes"][0])
+        self.assertEqual(
+            {"definition": definition, "arbitraryOption": 1},
+            listener.events[0].command["indexes"][0],
+        )
+
+        listener.reset()
+        with self.assertRaises(OperationFailure):
+            coll.create_search_index({"definition": definition, "type": "search"})
+        self.assertEqual(
+            {"definition": definition, "type": "search"}, listener.events[0].command["indexes"][0]
+        )
 
 
 class SearchIndexIntegrationBase(unittest.TestCase):