Peugeot 406 auxillary belt tensioner - silverspur2816
Hi all,
I'm new to this forum, so please bear with me if this has been asked before.
The 406 1.9TD is making an awful rattle on tick over, settles down above about 1200RPM. I orginally thought it was the timing belt tensioner bearings, but on closer inspection it seems to be the auxillary belt automatic tensioner pulley - the bearings are shot. I can actually see the pully jumping about as it ticks over and chatters. They Heynes manual does not show how to change this. I loosened the bolt that I think is holding it to the block. Although the pulley assembly can now be moved away from the block, it springs back. Any ideas? Also the bolt that I slackened off is too long to come out. Can this be changed with the engine in situ? It has air conditioning, if that makes a difference to the job.

Many thanks.
Peugeot 406 auxillary belt tensioner - Canuck
My 406 doesn't have air conditioning so this may not help, but I would seriously check the crankshaft pulley for one of two faults, the first being that the bolt into the crankshaft is loose and the pulley is rattling. The second possibility is that the crankshaft pulley is coming apart. The pulley is made of two concentric pieces shrunk together with a rubber insert between them. These inserts can fail = new pulley time.

Best way to inspect is raise and secure car, remove RH wheel and then front plastic wing liner. You should be able to see the scene from there.

I say this because my 406 made exactly the same noise, stopping at 1500 rpm and the crankshaft pulley was the cause, it ain't uncommon.

Peugeot 406 auxillary belt tensioner - LeePower

This is a really easy job on a 405 / 406 You need a 6mm allen key & a 4mm allen key or drill bit + a square drive socket handle.
Remove the right front wheel & support the car with an axel stand.
Remove the plastic wheel arch liner.
You will see the spring loaded tensioner in front of you, Place a square drive handle out of a socket set in the square hole in the bottom of the tensioner & push against the spring pressure untill you can place your 4mm drill bit or allen key in the hole to lock the tensioner off.
Undo the 2 6mm allen bolts & the tensioner will be free from your engine, NOTE where the belt goes FIRST!
Remove the plastic pully wheel from the end of the tensioner & aim the wheel towards your bin!
Fit your new wheel to the tensioner & a drop of locking compound is a good idea on the bolt.
Refit to the engine, a little locking compound on the bolts dosnt hurt, theres another plastic wheel bolted to the side of the engine so replace this whilst you can get at it & stick a new belt on as well, make sure its the right one & line the ribs up in the pullys.
An helper is a good idea whilst you remove your locking bit or allen key from the tensioner.
Put the car back together & run up & check your work.
Ive done this on 2 405s & a 406, about an hour for a first attemp.
Peugeot 406 auxillary belt tensioner - LeePower

I forgot to say that the wheel on the tensioner & the wheel on the engine are the same part no & cost about £12 each from a Peugeot dealer

Dont let them fit you up with a whole new tensioner, just get the 2 wheels & a belt.
Peugeot 406 auxillary belt tensioner - Reggie
I put a new auxillary belt on my 406 2.1td, which has air conditioning, but could not find the hole that you are supposed to put the 4mm drill bit in, that locks the spring pressure off, and so I guessed where the pulley wheel needed "locking up", when I refitted the belt.

I have done this twice now, and all seems well. But I am intrigued as to where the "hole" is that locks the pulley, and wonder, does it automatically tension the belt, as mine appears to be locked in position.

Also, I only remember one allen key and a square hole, not two as you describe. I don't suppose that there are two different types of tensioner are there?

Peugeot 406 auxillary belt tensioner - LeePower

There could be more then one, Ive never done a diesel one, Ive only done them on XU10J2 & XU10J4 Engines.

There should be a small round hole near the bottem right hand corner of the tensioners body, you slip the drill bit or allen key in there as you take the tension off with your socket bar.
The tensioner is under really strong spring pressure as well.

Never done a 2.1 td, thats a rare beast in a 406 & If you see one in a scrappy get the speedo clock set, these are very rare, expensive new, & in demand second hand!
Peugeot 406 auxillary belt tensioner - greaser pv
Just done one on a 406 diesel yesterday ! What a fun job .Yes the tensioner does have a 3/8 sized square for taking the tension off the belt , and there is a hole for locking it to itself . I think that reggie may just have renewed the jockey wheel ( which is also adjustable ). The one that I repaired had the tensioner bolt snapped off inside the internal sleeve of the tensioner , obviously not an uncommon fault as Peugeots supply a new one with the tensioner . The tensioner wheel and the jockey wheel on this car were not the same size . BTW the tensioner , jockey wheel and new tensioner spring cost approx. £180 even with the drivers ( taxi ) 10 % discount . This is not an easy job and took me around 3 hours ( it was my first attempt ) although I did encounter problems .
Peugeot 406 auxillary belt tensioner - greaser pv
As an added built-in peugeot extra , that I forgot to mention , the wheel on the tensioner has to be removed first before the tensioner can be replaced as there is not enough room to get the whole assembly out in one . Nice !
Peugeot 406 auxillary belt tensioner - LeePower


On the XU10J2 & XU10J4 petrol engines the wheel can be left on, theres lots of room for the tensioner to be removed & refitted with ease.
Peugeot 406 auxillary belt tensioner - silverspur2816
Thanks for the replies guys. It's definitly not the crank pulley nut loose, couldn't shift the thing!

I'm trying to remember how it went exactly now, as I'm 150 miles from the car which belongs to a mate! There are two wheels. One is an eccentric wheel, this comes off easy with one allen headed bolt, and is the manual adjustment. It's the other one giving us trouble, the automatic tensioner. I could only see one bolt holding it to the block. It's too long to remove the bolt completely. ANd with it loose, the tensioner does move a little, but springs back towards the block, so how do I get it off? I would have though if there is another bolt somewhere, I wouldn't be able to move it at all?

And I thought though my first car, a mini was tight to work on!!!

Thanks again, ALan.
Peugeot 406 auxillary belt tensioner - greaser pv
There is a heavy duty spring which is also attached to the tensioner from the other side . You will have to remove the air intake pipe the oil cooler pipe and the electrical switch to access the allen key bolt at the bottom of the spring the top one is easier. the central bolt 19mm is only a holding bolt the tensioner pivots around it , the tensioner wheel has to be removed first to allow the tensioner to come out , it is also an interference fit into the mounting bracket . See my previous posts.
Peugeot 406 auxillary belt tensioner - johnny boy
i have 2.0L HDI A/C, would this be the same as you describe?, when you talk about belt is that the cambelt.

something on the drivers side is rattling but at 1000rpm it goes, i wonder if it is this pulley

thanks johnny boy

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