Magento 2 Seo title product override not working

I overrided the Magento\Catalog\Block\Product\View.php adding this code

protected function _prepareLayout() {     parent::_prepareLayout();     $  this->pageConfig->getTitle()->set($  title . '- suffix');      return $  this; } 

And added the <preference for="Magento\Catalog\Block\Product\View" type="Indetach\Catalog\Block\Product\View" />

But it’s not working….