If you look at this picture, I believe your tensioner is No: 12 which is different to the standard 2.5TDi.

 

I have found something that looks like that when I've searched on the internet but not not sure how to remove the tension and if it is self adjusting or not. Its very difficult to see anything on the van/engine itself.

 

It is self adjusting as it's under a strong spring. There is no need to remove it.
Normally if you grab the belt underneath the van there is enough "Give" in the tensioner to get the old belt off & a new one on.
If you struggle have an assistant to put the belt over the power steering pully whilst you pull down the slack on the belt.

 

I already read on another thread that it should be possible to do that so I have tried to do that already but it barely moved and so I left it as I don't think I'd get the new one on. I have changed several of these belts on other cars with no problem over the years and it is normally a 2 minute job with a single spanner at most but the tension on this is very strong and I presume there must be something that can be levered on to back the tension off but due to the chassis leg I can't see what or how. There is currently an air con compressor fitted which I will be removing when I do the job as its not used on my van (not the original engine) and I think there is a redundant pulley to remove as well, I don't want to take the job on though without knowledge of the tensioner first as it could turn into a disaster otherwise once I cut/pry the old belt off.

 

Have you tried the German forums? Google translate is normally pretty good these days. They may even have a how to.

 

I've searched the internet using many variations but nothing has come up. Is there any other way of searching you know of or any forums I should look on.

 

The government or your isp may be blocking any access abroad. (Not kidding) I use a VPN to get there.
See if this link works for you.

Suchergebnisse - T4Forum.de

VW Bus Forum | www.t4forum.de | Wir - sind das T4Forum

www.t4forum.de

 

Here's a pic of the location.

Hydrolager – T4-Wiki

www.t4-wiki.de

 

What I can gather the tension is released using an allen key in the top of the tensioner.

 

Because the AXG had to be moved 10mm to the right to accomodate the bigger flywheel, they had to use a new type of hydraulic tensioner unique to that engine due to space constraints.

This might give some info to help, you'll have to bung it through Google Translate: Riemenspanner – T4-Wiki

 

Thanks for all the help. Can't seem to find a how to guide but after reading all the information and looking at the photos of the tensioner it looks to me like there is a hex part to put a socket on at the top of the damper. I presume you can try to compress the damper with that, only problem is that it looks very difficult to get at and then trying to apply the force in the right direction to compress it looks almost impossible, maybe the engine mount needs to be removed so it can be done from above.

 

I did this job last week on my 2.5 (ACV) and managed it with a LONG flathead screwdriver. If you put it under the tensioner pulley (highest one up closet to rear) and place screwdriver under the pulley and pull down it should move the pulley forward enough to slip the belt on dude

 

Thanks for the information. I did this job yesterday and the tensioner cannot be accessed at all without removing the intake and engine mount so I decided to do it without touching the tensioner. I took the power steering pump pulley off then once the belt was fitted round all the pulleys (including power steering pulley) I used a bar off the chassis leg to lever the pulley back onto the pump shaft. Was ok in the end, hardest part was getting the belt over the tensioning pulley.

Just noticed on your photo I think my power steering pulley is fitted the other way round to yours, not sure if it matters or which way is correct.