diff --git a/scrapy/utils/reqser.py b/scrapy/utils/reqser.py
index 78e13ec10..1392b2c61 100644
--- a/scrapy/utils/reqser.py
+++ b/scrapy/utils/reqser.py
@@ -70,20 +70,6 @@ def request_from_dict(d, spider=None):
     )
 
 
-def _is_private_method(name):
-    return name.startswith('__') and not name.endswith('__')
-
-
-def _mangle_private_name(obj, func, name):
-    qualname = getattr(func, '__qualname__', None)
-    if qualname is None:
-        classname = obj.__class__.__name__.lstrip('_')
-        return '_%s%s' % (classname, name)
-    else:
-        splits = qualname.split('.')
-        return '_%s%s' % (splits[-2], splits[-1])
-
-
 def _find_method(obj, func):
     if obj:
         try:
@@ -95,8 +81,6 @@ def _find_method(obj, func):
                 members = inspect.getmembers(obj, predicate=inspect.ismethod)
                 for name, obj_func in members:
                     if obj_func.__func__ is func.__func__:
-                        if _is_private_method(name):
-                            return _mangle_private_name(obj, func, name)
                         return name
     raise ValueError("Function %s is not a method of: %s" % (func, obj))
 
diff --git a/tests/test_utils_reqser.py b/tests/test_utils_reqser.py
index cf84f8fbd..47853d812 100644
--- a/tests/test_utils_reqser.py
+++ b/tests/test_utils_reqser.py
@@ -2,7 +2,7 @@ import unittest
 
 from scrapy.http import Request, FormRequest
 from scrapy.spiders import Spider
-from scrapy.utils.reqser import request_to_dict, request_from_dict, _is_private_method, _mangle_private_name
+from scrapy.utils.reqser import request_to_dict, request_from_dict
 
 
 class RequestSerializationTest(unittest.TestCase):
@@ -101,41 +101,6 @@ class RequestSerializationTest(unittest.TestCase):
                     errback=self.spider.handle_error)
         self._assert_serializes_ok(r, spider=self.spider)
 
-    def test_private_callback_name_matching(self):
-        self.assertTrue(_is_private_method('__a'))
-        self.assertTrue(_is_private_method('__a_'))
-        self.assertTrue(_is_private_method('__a_a'))
-        self.assertTrue(_is_private_method('__a_a_'))
-        self.assertTrue(_is_private_method('__a__a'))
-        self.assertTrue(_is_private_method('__a__a_'))
-        self.assertTrue(_is_private_method('__a___a'))
-        self.assertTrue(_is_private_method('__a___a_'))
-        self.assertTrue(_is_private_method('___a'))
-        self.assertTrue(_is_private_method('___a_'))
-        self.assertTrue(_is_private_method('___a_a'))
-        self.assertTrue(_is_private_method('___a_a_'))
-        self.assertTrue(_is_private_method('____a_a_'))
-
-        self.assertFalse(_is_private_method('_a'))
-        self.assertFalse(_is_private_method('_a_'))
-        self.assertFalse(_is_private_method('__a__'))
-        self.assertFalse(_is_private_method('__'))
-        self.assertFalse(_is_private_method('___'))
-        self.assertFalse(_is_private_method('____'))
-
-    def _assert_mangles_to(self, obj, name):
-        func = getattr(obj, name)
-        self.assertEqual(
-            _mangle_private_name(obj, func, func.__name__),
-            name
-        )
-
-    def test_private_name_mangling(self):
-        self._assert_mangles_to(
-            self.spider, '_TestSpider__parse_item_private')
-        self._assert_mangles_to(
-            self.spider, '_TestSpiderMixin__mixin_callback')
-
     def test_unserializable_callback1(self):
         r = Request("http://www.example.com", callback=lambda x: x)
         self.assertRaises(ValueError, request_to_dict, r)