Chain tensioner

[Phil Dunning]

I have a 2006 model D4D where is the chain tensioner and can it be replaced without taking the engine out please

[TonyHSD]

Hi, 

on most Toyota engine timing chain tensioner is easily replaced from the back of the engine. There are two 10mm nuts and the tensioner goes out. 
Before you do that you need to set timing on the crankshaft pulley so markings match 0”  

What are the reasons to replace timing chain tensioner? 
Have you opened to inspect the timing chain tension? 
Do you get rattling on start up? 

Here is my timing chain tensioner replacement on hybrid 1.8 if this can be of any help , it’s on page 2 .