Hello everyone. I know this subject has been brought up many times, but in doing some research I still have a few questions. I bought a 2003 Vanden Plas two years ago with around 85K miles and it currently sits at around 93K. When I first got the car I was under the impression that they had switched to using the metal tensioner by 2003, but I recently have seen a few articles stating that they didn't make the switch until 2005 and that I most likely have a second gen plastic tensioner that has the spring and more plastic reinforcement (assuming it wasn't already replaced). I've seen a lot of conflicting info on this subject and just wondered if anyone has a definitive answer? Any help would be appreciated.

 

Remember to post an introduction in the New Member area to receive a proper welcome to the forum.

If your X308 is a 2003 MY, it's fitted with the AJ27, which should the updated secondary timing chain tensioners. The engine number stamped on the block near the thermostat housing can be used to verify if the engine has the newer style tensioners.

 

mhershey84,
Like you I have read that the 2003 X308s were fitted with the upgraded MkIII tensioners, and have also read other reports that this was not done until 2004 or later. So my advice would be to remove the passenger-side valve cover whereby you can visually check the secondary tensioners to confirm they are of the MkIII type.









The engine number near the thermostat tower applies to earlier pre-2000 X308s, your engine number is stamped on the engine block and visible from under the left-hand front wheel arch.

 

And then to complicate things further, later versions of the A27 had upgraded continuously variable valve timing (CVVT) units and "mutli-row" Morse-type timing chains, which were then continued into the X350 4.2-and-on versions of the engine.
I'm unsure as to when these were introduced, but I did find this info from an earlier post by forum member "motorcarman"....

"The timing chains to engine (0108122359) are the normal roller. The timing chains FROM Engine (0108130000) are the 'Morse' silent running chains. The sprockets and guides are also different".

 

The PRIMARY chains are the 'silent-running' Morse style chains.
The secondaries are still the regular roller chains.

 

the entire chain system was redone by tsubaki and introduced in august 13 01. the only part that carried over was the secondary chain.

this is when the metal tensioners, primary and secondary were introduced and also the metal backed guides with a plastic slipper

 

It's an 03-you're good to go.
I have 2 xjr's(December 01 build dates) and they have all the 3rd gen stuff from factory. My dad has an 03 xjr. Also has all the 3rd gen timing stuff. I always pull a cam cover off these cars to check.

 

Thanks for the advice everyone. I'll probably pull the cam cover off when it warms up just to double check.