Tensioner Slipping after Belt (and Tensioner) Change

[The Hairy Camper]

I recently bought a new belt and tensioner to put on my diesel T3. I've just had the fuel pump rebuilt and thought I might as well fit a new belt and tensioner when I reinstall it.

After fitting the belt today (3 times), I noticed the timing was out by about 1 tooth after rotating everything twice.

I couldn't figure what I was doing wrong as I've changed the belts on my van a couple times before with no issues, but I noticed during the 3rd time fitting the belt again today that the new tensioner seems to be slipping. It has 2 marks that have to line up. They are lining up on install, but it slips after rotating. I torqued to 25nm in the end, the instructions say 20nm should be enough.

Can anyone help? I may have replaced the bolt that the tensioner sits on too. Could that be slipping? Does it need locktite on the threads going to the block?

Appreciate any info.
Cheers.

[Simon Baxter]

Preume 1.9l with that tensioner, have you located the tensioner peg properly.

[The Hairy Camper]

Yes, I double checked this today. I replaced the tensioner guide stud too, but I didn't apply any locktite to it's threads. The stud can apparently come loose if you don't do this, so that's the next course of action when I get chance.

[davidoft1]

It’s a spring loaded tensioner right? It will move around, have you reset it once turning the engine over by hand a couple of times ?

[The Hairy Camper]

I had some more time to work on the van this morning.
I added some thread lock to the tensioner stud, refit the belt, located the tensioner spring arm thing, tightened the tensioner and torqued the crank pulley. The tensioner was slightly off it's mark after I tightened up the crank pulley, so I reset the tensioner mark again before rotating the cam pulley/engine twice.

The tensioner mark had slipped slightly again. I reset the tensioner and checked all the timing marks lined up (they were spot on).

I rotated the engine 2 more times and the mark was slightly off again. All the timing marks lined up though, so I decided to start the engine.

Engine started up and sounded great.
After running the engine for a minute or 2, I checked the tensioner again, still slightly off, but all the timing marks are spot...so I'm assuming everything is fine?

It's probably just OCD, but does what does everyone think? I've ordered a new tensioner stud, my tensioner is 6 months old (basically new), Is it worth getting another one? I've never noticed the tensioner being off on previous belt changes.

[davidoft1]

I had some more time to work on the van this morning.
I added some thread lock to the tensioner stud, refit the belt, located the tensioner spring arm thing, tightened the tensioner and torqued the crank pulley. The tensioner was slightly off it's mark after I tightened up the crank pulley, so I reset the tensioner mark again before rotating the cam pulley/engine twice.

The tensioner mark had slipped slightly

again. I reset the tensioner and checked all the timing marks lined up (they were spot on).

I rotated the engine 2 more times and the mark was slightly off again. All the timing marks lined up though, so I decided to start the engine.

Engine started up and sounded great.
After running the engine for a minute or 2, I checked the tensioner again, still slightly off, but all the timing marks are spot...so I'm assuming everything is fine?

It's probably just OCD, but does what does everyone think? I've ordered a new tensioner stud, my tensioner is 6 months old (basically new), Is it worth getting another one? I've never noticed the tensioner being off on previous belt changes.

It’s a spring loaded tensioner right? It will move around, have you reset it once turning the engine over by hand a couple of times ?

[The Hairy Camper]

I've reset the tensioner 3 times total today. Twice after the engine was rotated by hand. The marks will not stay lined up.

I ran the engine a few times today, the tensioner doesn't seem to be shifting position now , but stays in the position shown in the last photo in my above post.

The timing marks all line up fine, but the two marks on the tensioner refuse to stay lined up with each other.

I could reset it a 4th time, but I doubt it would stay lined up.

Does this sound normal for diesel T3's?

[davidoft1]

I've reset the tensioner 3 times total today. Twice after the engine was rotated by hand. The marks will not stay lined up.

I ran the engine a few times today, the tensioner doesn't seem to be shifting position now , but stays in the position shown in the last photo in my above post.

The timing marks all line up fine, but the two marks on the tensioner refuse to stay lined up with each other.

I could reset it a 4th time, but I doubt it would stay lined up.

Does this sound normal for diesel T3's?

t’s a spring loaded tensioner right? It will move around, have you reset it once turning the engine over by hand a couple of times ?
 

[The Hairy Camper]

You might want to re-read the message you quoted David.

I've run the van loads of times since and everything seems fine. The tensioner does indeed move around slightly, so I will assume this is normal.

Here's it's latest position:


It's almost spot on! It's almost like it's messing with me