diff --git a/app/controllers/admin/services_controller.rb b/app/controllers/admin/services_controller.rb
index a62170662e12c34070374c69f6396a616b82aeeb..461335883325e2c7b33b29c83114ce6ff880e5db 100644
--- a/app/controllers/admin/services_controller.rb
+++ b/app/controllers/admin/services_controller.rb
@@ -39,7 +39,13 @@ class Admin::ServicesController < Admin::ApplicationController
   end
 
   def application_services_params
-    params.permit(:id,
+    application_services_params = params.permit(:id,
       service: Projects::ServicesController::ALLOWED_PARAMS)
+    if application_services_params[:service].is_a?(Hash)
+      Projects::ServicesController::FILTER_BLANK_PARAMS.each do |param|
+        application_services_params[:service].delete(param) if application_services_params[:service][param].blank? 
+      end
+    end
+    application_services_params
   end
 end
diff --git a/app/controllers/projects/services_controller.rb b/app/controllers/projects/services_controller.rb
index 3047ee8a1ff02db6b068541daa467334b074e436..129068ef0192ed4c0e95d01c91237d212df75cd2 100644
--- a/app/controllers/projects/services_controller.rb
+++ b/app/controllers/projects/services_controller.rb
@@ -9,6 +9,10 @@ class Projects::ServicesController < Projects::ApplicationController
                     :note_events, :send_from_committer_email, :disable_diffs, :external_wiki_url,
                     :notify, :color,
                     :server_host, :server_port, :default_irc_uri, :enable_ssl_verification]
+
+  # Parameters to ignore if no value is specified
+  FILTER_BLANK_PARAMS = [:password]
+  
   # Authorize
   before_action :authorize_admin_project!
   before_action :service, only: [:edit, :update, :test]
@@ -59,7 +63,9 @@ class Projects::ServicesController < Projects::ApplicationController
 
   def service_params
     service_params = params.require(:service).permit(ALLOWED_PARAMS)
-    service_params.delete("password") if service_params["password"].blank?
+    FILTER_BLANK_PARAMS.each do |param|
+      service_params.delete(param) if service_params[param].blank?
+    end
     service_params
   end
 end
diff --git a/app/models/project_services/bamboo_service.rb b/app/models/project_services/bamboo_service.rb
index 5f5255ab48727398a285a8d2247b222189de587a..d31b12f539e9bb9dee0e3903761d418f7d2004e4 100644
--- a/app/models/project_services/bamboo_service.rb
+++ b/app/models/project_services/bamboo_service.rb
@@ -48,7 +48,7 @@ class BambooService < CiService
   end
 
   def reset_password
-    if prop_updated?(:bamboo_url)
+    if bamboo_url_changed? && !password_touched?
       self.password = nil
     end
   end
diff --git a/app/models/project_services/teamcity_service.rb b/app/models/project_services/teamcity_service.rb
index fb11cad352ed014e3ac818a6bb2cbbf3c24d04ac..0b0224612505e18f81386b5442103193865f5d29 100644
--- a/app/models/project_services/teamcity_service.rb
+++ b/app/models/project_services/teamcity_service.rb
@@ -45,7 +45,7 @@ class TeamcityService < CiService
   end
 
   def reset_password
-    if prop_updated?(:teamcity_url)
+    if teamcity_url_changed? && !password_touched?
       self.password = nil
     end
   end
diff --git a/app/models/service.rb b/app/models/service.rb
index 7e845d565b1c4c7cdcc712d89621b49d2f37885a..d610abd16837ce1760d2a4585050f2b0b10f0944 100644
--- a/app/models/service.rb
+++ b/app/models/service.rb
@@ -33,6 +33,8 @@ class Service < ActiveRecord::Base
 
   after_initialize :initialize_properties
 
+  after_commit :reset_updated_properties
+
   belongs_to :project
   has_one :service_hook
 
@@ -103,6 +105,7 @@ class Service < ActiveRecord::Base
 
   # Provide convenient accessor methods
   # for each serialized property.
+  # Also keep track of updated properties in a similar way as ActiveModel::Dirty
   def self.prop_accessor(*args)
     args.each do |arg|
       class_eval %{
@@ -111,21 +114,39 @@ class Service < ActiveRecord::Base
         end
 
         def #{arg}=(value)
+          updated_properties['#{arg}'] = #{arg} unless #{arg}_changed?
           self.properties['#{arg}'] = value
         end
+
+        def #{arg}_changed?
+          #{arg}_touched? && #{arg} != #{arg}_was
+        end
+
+        def #{arg}_touched?
+          updated_properties.include?('#{arg}')
+        end
+
+        def #{arg}_was
+          updated_properties['#{arg}']
+        end
       }
     end
   end
 
-  # ActiveRecord does not provide a mechanism to track changes in serialized keys.
-  # This is why we need to perform extra query to do it mannually.
-  def prop_updated?(prop_name)
-    relation_name = self.type.underscore
-    previous_value = project.send(relation_name).send(prop_name)
-    return false if previous_value.nil?
-    previous_value != send(prop_name)
+  # Returns a hash of the properties that have been assigned a new value since last save,
+  # indicating their original values (attr => original value).
+  # ActiveRecord does not provide a mechanism to track changes in serialized keys, 
+  # so we need a specific implementation for service properties.
+  # This allows to track changes to properties set with the accessor methods,
+  # but not direct manipulation of properties hash.
+  def updated_properties
+    @updated_properties ||= ActiveSupport::HashWithIndifferentAccess.new
   end
 
+  def reset_updated_properties
+    @updated_properties = nil
+  end
+  
   def async_execute(data)
     return unless supported_events.include?(data[:object_kind])
 
diff --git a/spec/models/project_services/bamboo_service_spec.rb b/spec/models/project_services/bamboo_service_spec.rb
index f8a3493f52df63b0c050b7da3f6d2a936273c9a5..c34b2487ecfa6721dc88bb115d11f0cb991517c4 100644
--- a/spec/models/project_services/bamboo_service_spec.rb
+++ b/spec/models/project_services/bamboo_service_spec.rb
@@ -30,27 +30,65 @@ describe BambooService, models: true do
     let(:user)    { create(:user) }
     let(:project) { create(:project) }
 
-    before do
-      @bamboo_service = BambooService.create(
-        project: create(:project),
-        properties: {
-          bamboo_url: 'http://gitlab.com',
-          username: 'mic',
-          password: "password"
-        }
-      )
-    end
+    context "when a password was previously set" do
+      before do
+        @bamboo_service = BambooService.create(
+          project: create(:project),
+          properties: {
+            bamboo_url: 'http://gitlab.com',
+            username: 'mic',
+            password: "password"
+          }
+        )
+      end
+  
+      it "reset password if url changed" do
+        @bamboo_service.bamboo_url = 'http://gitlab1.com'
+        @bamboo_service.save
+        expect(@bamboo_service.password).to be_nil
+      end
+  
+      it "does not reset password if username changed" do
+        @bamboo_service.username = "some_name"
+        @bamboo_service.save
+        expect(@bamboo_service.password).to eq("password")
+      end
+
+      it "does not reset password if new url is set together with password, even if it's the same password" do
+        @bamboo_service.bamboo_url = 'http://gitlab_edited.com'
+        @bamboo_service.password = 'password'
+        @bamboo_service.save
+        expect(@bamboo_service.password).to eq("password")
+        expect(@bamboo_service.bamboo_url).to eq("http://gitlab_edited.com")
+      end
 
-    it "reset password if url changed" do
-      @bamboo_service.bamboo_url = 'http://gitlab1.com'
-      @bamboo_service.save
-      expect(@bamboo_service.password).to be_nil
+      it "should reset password if url changed, even if setter called multiple times" do
+        @bamboo_service.bamboo_url = 'http://gitlab1.com'
+        @bamboo_service.bamboo_url = 'http://gitlab1.com'
+        @bamboo_service.save
+        expect(@bamboo_service.password).to be_nil
+      end
     end
+    
+    context "when no password was previously set" do
+      before do
+        @bamboo_service = BambooService.create(
+          project: create(:project),
+          properties: {
+            bamboo_url: 'http://gitlab.com',
+            username: 'mic'
+          }
+        )
+      end
+
+      it "saves password if new url is set together with password" do
+        @bamboo_service.bamboo_url = 'http://gitlab_edited.com'
+        @bamboo_service.password = 'password'
+        @bamboo_service.save
+        expect(@bamboo_service.password).to eq("password")
+        expect(@bamboo_service.bamboo_url).to eq("http://gitlab_edited.com")
+      end
 
-    it "does not reset password if username changed" do
-      @bamboo_service.username = "some_name"
-      @bamboo_service.save
-      expect(@bamboo_service.password).to eq("password")
     end
   end
 end
diff --git a/spec/models/project_services/teamcity_service_spec.rb b/spec/models/project_services/teamcity_service_spec.rb
index 3dbd2346bccd0eff9966e16382efa19f8f72f1ab..f26b47a856c5058091ba31184b1af6ca1ef2853f 100644
--- a/spec/models/project_services/teamcity_service_spec.rb
+++ b/spec/models/project_services/teamcity_service_spec.rb
@@ -30,27 +30,64 @@ describe TeamcityService, models: true do
     let(:user)    { create(:user) }
     let(:project) { create(:project) }
 
-    before do
-      @teamcity_service = TeamcityService.create(
-        project: create(:project),
-        properties: {
-          teamcity_url: 'http://gitlab.com',
-          username: 'mic',
-          password: "password"
-        }
-      )
-    end
+    context "when a password was previously set" do
+      before do
+        @teamcity_service = TeamcityService.create(
+          project: create(:project),
+          properties: {
+            teamcity_url: 'http://gitlab.com',
+            username: 'mic',
+            password: "password"
+          }
+        )
+      end
+  
+      it "reset password if url changed" do
+        @teamcity_service.teamcity_url = 'http://gitlab1.com'
+        @teamcity_service.save
+        expect(@teamcity_service.password).to be_nil
+      end
+  
+      it "does not reset password if username changed" do
+        @teamcity_service.username = "some_name"
+        @teamcity_service.save
+        expect(@teamcity_service.password).to eq("password")
+      end
+
+      it "does not reset password if new url is set together with password, even if it's the same password" do
+        @teamcity_service.teamcity_url = 'http://gitlab_edited.com'
+        @teamcity_service.password = 'password'
+        @teamcity_service.save
+        expect(@teamcity_service.password).to eq("password")
+        expect(@teamcity_service.teamcity_url).to eq("http://gitlab_edited.com")
+      end
 
-    it "reset password if url changed" do
-      @teamcity_service.teamcity_url = 'http://gitlab1.com'
-      @teamcity_service.save
-      expect(@teamcity_service.password).to be_nil
+      it "should reset password if url changed, even if setter called multiple times" do
+        @teamcity_service.teamcity_url = 'http://gitlab1.com'
+        @teamcity_service.teamcity_url = 'http://gitlab1.com'
+        @teamcity_service.save
+        expect(@teamcity_service.password).to be_nil
+      end
     end
+    
+    context "when no password was previously set" do
+      before do
+        @teamcity_service = TeamcityService.create(
+          project: create(:project),
+          properties: {
+            teamcity_url: 'http://gitlab.com',
+            username: 'mic'
+          }
+        )
+      end
 
-    it "does not reset password if username changed" do
-      @teamcity_service.username = "some_name"
-      @teamcity_service.save
-      expect(@teamcity_service.password).to eq("password")
+      it "saves password if new url is set together with password" do
+        @teamcity_service.teamcity_url = 'http://gitlab_edited.com'
+        @teamcity_service.password = 'password'
+        @teamcity_service.save
+        expect(@teamcity_service.password).to eq("password")
+        expect(@teamcity_service.teamcity_url).to eq("http://gitlab_edited.com")
+      end
     end
   end
 end
diff --git a/spec/models/service_spec.rb b/spec/models/service_spec.rb
index da87ea5b84f175ce7835d6708021cf03558bf10d..692e5fda3ba9e7ead1d78e1b57bd42a6281f1b38 100644
--- a/spec/models/service_spec.rb
+++ b/spec/models/service_spec.rb
@@ -104,7 +104,7 @@ describe Service do
     end
   end
 
-  describe "#prop_updated?" do
+  describe "{property}_changed?" do
     let(:service) do
       BambooService.create(
         project: create(:project),
@@ -116,14 +116,112 @@ describe Service do
       )
     end
 
-    it "returns false" do
+    it "returns false when the property has not been assigned a new value" do
       service.username = "key_changed"
-      expect(service.prop_updated?(:bamboo_url)).to be_falsy
+      expect(service.bamboo_url_changed?).to be_falsy
     end
 
-    it "returns true" do
-      service.bamboo_url = "http://other.com"
-      expect(service.prop_updated?(:bamboo_url)).to be_truthy
+    it "returns true when the property has been assigned a different value" do
+      service.bamboo_url = "http://example.com"
+      expect(service.bamboo_url_changed?).to be_truthy
+    end
+
+    it "returns true when the property has been assigned a different value twice" do
+      service.bamboo_url = "http://example.com"
+      service.bamboo_url = "http://example.com"
+      expect(service.bamboo_url_changed?).to be_truthy
+    end
+
+    it "returns false when the property has been re-assigned the same value" do
+      service.bamboo_url = 'http://gitlab.com'
+      expect(service.bamboo_url_changed?).to be_falsy
+    end
+
+    it "returns false when the property has been assigned a new value then saved" do
+      service.bamboo_url = 'http://example.com'
+      service.save
+      expect(service.bamboo_url_changed?).to be_falsy
+    end
+  end
+
+  describe "{property}_touched?" do
+    let(:service) do
+      BambooService.create(
+        project: create(:project),
+        properties: {
+          bamboo_url: 'http://gitlab.com',
+          username: 'mic',
+          password: "password"
+        }
+      )
+    end
+
+    it "returns false when the property has not been assigned a new value" do
+      service.username = "key_changed"
+      expect(service.bamboo_url_touched?).to be_falsy
+    end
+
+    it "returns true when the property has been assigned a different value" do
+      service.bamboo_url = "http://example.com"
+      expect(service.bamboo_url_touched?).to be_truthy
+    end
+
+    it "returns true when the property has been assigned a different value twice" do
+      service.bamboo_url = "http://example.com"
+      service.bamboo_url = "http://example.com"
+      expect(service.bamboo_url_touched?).to be_truthy
+    end
+
+    it "returns true when the property has been re-assigned the same value" do
+      service.bamboo_url = 'http://gitlab.com'
+      expect(service.bamboo_url_touched?).to be_truthy
+    end
+
+    it "returns false when the property has been assigned a new value then saved" do
+      service.bamboo_url = 'http://example.com'
+      service.save
+      expect(service.bamboo_url_changed?).to be_falsy
+    end
+  end
+
+  describe "{property}_was" do
+    let(:service) do
+      BambooService.create(
+        project: create(:project),
+        properties: {
+          bamboo_url: 'http://gitlab.com',
+          username: 'mic',
+          password: "password"
+        }
+      )
+    end
+
+
+    it "returns nil when the property has not been assigned a new value" do
+      service.username = "key_changed"
+      expect(service.bamboo_url_was).to be_nil
+    end
+
+    it "returns the previous value when the property has been assigned a different value" do
+      service.bamboo_url = "http://example.com"
+      expect(service.bamboo_url_was).to eq('http://gitlab.com')
+    end
+
+    it "returns initial value when the property has been re-assigned the same value" do
+      service.bamboo_url = 'http://gitlab.com'
+      expect(service.bamboo_url_was).to eq('http://gitlab.com')
+    end
+
+    it "returns initial value when the property has been assigned multiple values" do
+      service.bamboo_url = "http://example.com"
+      service.bamboo_url = "http://example2.com"
+      expect(service.bamboo_url_was).to eq('http://gitlab.com')
+    end
+
+    it "returns nil when the property has been assigned a new value then saved" do
+      service.bamboo_url = 'http://example.com'
+      service.save
+      expect(service.bamboo_url_was).to be_nil
     end
   end
 end