diff --git a/src/translate.directive.ts b/src/translate.directive.ts
index 4b8381e5..3c7b4a61 100644
--- a/src/translate.directive.ts
+++ b/src/translate.directive.ts
@@ -2,6 +2,8 @@ import {Directive, ElementRef, AfterViewChecked, Input, OnDestroy} from '@angula
 import {Subscription} from 'rxjs';
 import {isDefined} from './util';
 import {TranslateService, LangChangeEvent} from './translate.service';
+import {TranslationChangeEvent} from "./translate.service";
+import {DefaultLangChangeEvent} from "./translate.service";
 
 @Directive({
     selector: '[translate],[ng2-translate]'
@@ -11,6 +13,7 @@ export class TranslateDirective implements AfterViewChecked, OnDestroy {
     lastParams: any;
     onLangChangeSub: Subscription;
     onDefaultLangChangeSub: Subscription;
+    onTranslationChangeSub: Subscription;
 
     @Input() set translate(key: string) {
         if(key) {
@@ -22,17 +25,26 @@ export class TranslateDirective implements AfterViewChecked, OnDestroy {
     @Input() translateParams: any;
 
     constructor(private translateService: TranslateService, private element: ElementRef) {
+        // subscribe to onTranslationChange event, in case the translations of the current lang change
+        if(!this.onTranslationChangeSub) {
+            this.onTranslationChangeSub = this.translateService.onTranslationChange.subscribe((event: TranslationChangeEvent) => {
+                if(event.lang === this.translateService.currentLang) {
+                    this.checkNodes(true, event.translations);
+                }
+            });
+        }
+
         // subscribe to onLangChange event, in case the language changes
         if(!this.onLangChangeSub) {
             this.onLangChangeSub = this.translateService.onLangChange.subscribe((event: LangChangeEvent) => {
-                this.checkNodes(event.translations);
+                this.checkNodes(true, event.translations);
             });
         }
 
         // subscribe to onDefaultLangChange event, in case the default language changes
         if(!this.onDefaultLangChangeSub) {
-            this.onDefaultLangChangeSub = this.translateService.onDefaultLangChange.subscribe(() => {
-                this.checkNodes();
+            this.onDefaultLangChangeSub = this.translateService.onDefaultLangChange.subscribe((event: DefaultLangChangeEvent) => {
+                this.checkNodes(true);
             });
         }
     }
@@ -41,7 +53,7 @@ export class TranslateDirective implements AfterViewChecked, OnDestroy {
         this.checkNodes();
     }
 
-    checkNodes(translations?: any) {
+    checkNodes(forceUpdate = false, translations?: any) {
         let nodes: NodeList = this.element.nativeElement.childNodes;
         for(let i = 0; i < nodes.length; ++i) {
             let node: any = nodes[i];
@@ -57,7 +69,7 @@ export class TranslateDirective implements AfterViewChecked, OnDestroy {
                             key = content;
                             // the content was changed from the user, we'll use it as a reference if needed
                             node.originalContent = node.textContent;
-                        } else if(node.originalContent && isDefined(translations)) { // the content seems ok, but the lang has changed
+                        } else if(node.originalContent && forceUpdate) { // the content seems ok, but the lang has changed
                             node.lastKey = null;
                             // the current content is the translation, not the key, use the last real content as key
                             key = node.originalContent.trim();
@@ -111,5 +123,9 @@ export class TranslateDirective implements AfterViewChecked, OnDestroy {
         if(this.onDefaultLangChangeSub) {
             this.onDefaultLangChangeSub.unsubscribe();
         }
+
+        if(this.onTranslationChangeSub) {
+            this.onTranslationChangeSub.unsubscribe();
+        }
     }
 }
diff --git a/src/translate.service.ts b/src/translate.service.ts
index b51a8542..017e2058 100644
--- a/src/translate.service.ts
+++ b/src/translate.service.ts
@@ -7,6 +7,7 @@ import "rxjs/add/operator/share";
 import "rxjs/add/operator/map";
 import "rxjs/add/operator/merge";
 import "rxjs/add/operator/toArray";
+import "rxjs/add/operator/take";
 
 import {TranslateParser} from "./translate.parser";
 import {isDefined} from "./util";
@@ -129,6 +130,7 @@ export class TranslateService {
     /**
      *
      * @param currentLoader An instance of the loader currently used
+     * @param parser An instance of the parser currently used
      * @param missingTranslationHandler A handler for missing translations.
      */
     constructor(
@@ -142,6 +144,10 @@ export class TranslateService {
      * @param lang
      */
     public setDefaultLang(lang: string): void {
+        if(lang === this.defaultLang) {
+            return;
+        }
+
         let pending: Observable<any> = this.retrieveTranslations(lang);
 
         if(typeof pending !== "undefined") {
@@ -150,10 +156,10 @@ export class TranslateService {
                 this.defaultLang = lang;
             }
 
-            pending.subscribe((res: any) => {
-                this.changeDefaultLang(lang);
-            }, (err: any) => {
-            });
+            pending.take(1)
+                .subscribe((res: any) => {
+                    this.changeDefaultLang(lang);
+                });
         } else { // we already have this language
             this.changeDefaultLang(lang);
         }
@@ -180,10 +186,11 @@ export class TranslateService {
             if(!this.currentLang) {
                 this.currentLang = lang;
             }
-            pending.subscribe((res: any) => {
-                this.changeLang(lang);
-            }, (err: any) => {
-            });
+
+            pending.take(1)
+                .subscribe((res: any) => {
+                    this.changeLang(lang);
+                });
 
             return pending;
         } else { // we have this language, return an Observable
@@ -200,11 +207,12 @@ export class TranslateService {
      */
     private retrieveTranslations(lang: string): Observable<any> {
         let pending: Observable<any>;
-        // check if this language is available
+
+        // if this language is unavailable, ask for it
         if(typeof this.translations[lang] === "undefined") {
-            // not available, ask for it
             pending = this.getTranslation(lang);
         }
+
         return pending;
     }
 
@@ -215,13 +223,15 @@ export class TranslateService {
      */
     public getTranslation(lang: string): Observable<any> {
         this.pending = this.currentLoader.getTranslation(lang).share();
-        this.pending.subscribe((res: Object) => {
-            this.translations[lang] = res;
-            this.updateLangs();
-            this.pending = undefined;
-        }, (err: any) => {
-            this.pending = undefined;
-        });
+
+        this.pending.take(1)
+            .subscribe((res: Object) => {
+                this.translations[lang] = res;
+                this.updateLangs();
+                this.pending = undefined;
+            }, (err: any) => {
+                this.pending = undefined;
+            });
 
         return this.pending;
     }
@@ -235,11 +245,11 @@ export class TranslateService {
     public setTranslation(lang: string, translations: Object, shouldMerge: boolean = false): void {
         if(shouldMerge && this.translations[lang]) {
             Object.assign(this.translations[lang], translations);
-            this.onTranslationChange.emit({translations: this.translations[lang], lang: lang});
         } else {
             this.translations[lang] = translations;
         }
         this.updateLangs();
+        this.onTranslationChange.emit({lang: lang, translations: this.translations[lang]});
     }
 
     /**
@@ -317,15 +327,15 @@ export class TranslateService {
             res = this.parser.interpolate(this.parser.getValue(this.translations[this.defaultLang], key), interpolateParams);
         }
 
-        if (!res && this.missingTranslationHandler) {
-            let params: MissingTranslationHandlerParams = { key, translateService: this };
-            if (typeof interpolateParams !== 'undefined') {
+        if(!res && this.missingTranslationHandler) {
+            let params: MissingTranslationHandlerParams = {key, translateService: this};
+            if(typeof interpolateParams !== 'undefined') {
                 params.interpolateParams = interpolateParams;
             }
             res = this.missingTranslationHandler.handle(params);
         }
 
-        return res !== undefined ? res : key;
+        return typeof res !== "undefined" ? res : key;
     }
 
     /**
@@ -403,7 +413,7 @@ export class TranslateService {
     public set(key: string, value: string, lang: string = this.currentLang): void {
         this.translations[lang][key] = value;
         this.updateLangs();
-        this.onTranslationChange.emit({translations: {[key]: value}, lang: lang});
+        this.onTranslationChange.emit({lang: lang, translations: this.translations[lang]});
     }
 
     /**
@@ -413,6 +423,11 @@ export class TranslateService {
     private changeLang(lang: string): void {
         this.currentLang = lang;
         this.onLangChange.emit({lang: lang, translations: this.translations[lang]});
+
+        // if there is no default lang, use the one that we just set
+        if(!this.defaultLang) {
+            this.changeDefaultLang(lang);
+        }
     }
 
     /**
@@ -472,7 +487,7 @@ export class TranslateService {
      * @returns string
      */
     public getBrowserCultureLang(): string {
-        if (typeof window === 'undefined' || typeof window.navigator === 'undefined') {
+        if(typeof window === 'undefined' || typeof window.navigator === 'undefined') {
             return undefined;
         }
 
diff --git a/tests/translate.directive.spec.ts b/tests/translate.directive.spec.ts
index 950a5538..47737ec9 100644
--- a/tests/translate.directive.spec.ts
+++ b/tests/translate.directive.spec.ts
@@ -117,12 +117,11 @@ describe('TranslateDirective', () => {
 
     // Test (temporarily) disabled as the directive tests manipulate the DOM manually which breaks this test.
     // https://github.com/ocombe/ng2-translate/pull/336
-    xit('should update the DOM when the default lang changes', () => {
+    it('should update the DOM when the default lang changes', () => {
         expect(fixture.componentInstance.noKey.nativeElement.innerHTML).toEqual('TEST');
 
         translate.setTranslation('en', {"TEST": "This is a test"});
         translate.setTranslation('fr', {"TEST": "C'est un test"});
-
         translate.setDefaultLang('en');
         expect(fixture.componentInstance.noKey.nativeElement.innerHTML).toEqual('This is a test');