Chain tensioner

Bonjour, est ce normal que le tendeur de chaine sur le V12 monte et descende lorsque je tourne le moteur?
Merci de vos réponses

For those whose French is a little rusty:

“Hello, is it normal that the chain tensioner on the V12 goes up and down when I turn the engine?
Thank you for your answers”

English only version.
Not sure what “up and down” is exactly but the tensioner should have a bowed look to it and that bow should be more or less locked in.
It is important to remember NOT to rotate the engine in reverse direction. If this is done all tensioner bets are off.

La chaîne est bien tendue, les culasses ont eté refaites, lorsqu on tourne le moteur d un tour a la main, le tendeur monte et redescend ? Est ce normal ? Merci

Que est-ce que ça veut dire que le tendeur monte et redescend ?
Un fois bloqué il bouge pas.
Ce serait mieux si tu écris en Englais, pour que tout le monde puisse te comprendre.

J ai déposé les culasses, nouvelle soupape, joint de queue de soupape changés, tout est remonté, lorsque je tourne le vilebrequin d’un tour complet, il y a un clic a un moment, cela correspond à la descente de 2 cm (ou montée) du haut du tendeur qui glisse dans sa gorge, je vous ce mouvement par dessus au niveau pignon de came. Pourtant chaîne tendue, et il le tendeur a l air indemme. En principe il doit être fixe et ne doit pas bouger?

Hello, when i turn engine by hand, i see on the top, thé tensioner IS Moving UP,(2centimeters) next turn, IS Moving down? I Heard 2 clics when he moves down an up . Not normal i suppose

I would just like to say my “English only version” comment was simply to say that is my only language. It was in no way an instruction to fellow posters.

You sound as though you are describing a broken tensioner.

The only tensioner movement I would expect is that from left to right, not up and down, as you have described. The tensioner will only move when the engine rpm changes rapidly.

Take a look at Help Anybody know how to manipulate the chain and chain tensioner on a V12 HE and read the whole thread to decide whether your timing chain is worn down too much.

See also which shows a broken tensioner which will skip up and down as you describe and also make a rattling noise if the engine is running.

kind regards

Once the tensioner is unlocked there should be no movement in any direction because it has a non return feature and can only extend to compensate for chain or damper wear.
If it is moving, you either haven’t unlocked it (access lock thru the front cover hole) or the engine has been turned in reverse and broken it.

Merci Marek pour vos explications et photos, je vais démonter le carter et voir de visu.
J’ ai une autre question pour vous concernant le démontage de la poulie du vilebrequin, comment le bloquer pour deserer l écrou central, je pensais mettre une douille sur l écrou, la clé a douille, bloquer cette clé et donner un coup de démarreur?

Merci pour votre réponse, je démonte le carter et je regarde le tendeur.
Cordialement. Wlad

I would remove the cover over the bottom of the flywheel, wedge some wood blocks into the gap so the flywheel cannot turn and use a socket with a very long handle (1m-1.5m) (I use a length of scaffolding pipe for this). Using the starter motor may work but will make the spanner hit the engine frame very hard and maybe damage it.

Norman is quite right - the tensioner should always stay tensioned and slowly move across from right to left as the chain wears over many years. There is only very limited scope for it to move from side to side and this is constrained by the rubber plates which are there to stop it whipping left or right as the engine rpm changes.

kind regards

Merci Marek, mon tendeur était bien cassé, concernant le calage moteur, après mise en place des plaques d arbre a cames avec repére a midi, le repère 1 A sur vilebrequin doit être aligné sur 0 sur plaque , ou 12 degré avant? Merci a tous wladislas

0 degrees

You are only reassembling mechanical parts of the engine (i.e. how the crank and camshafts work relative to each other) and that is not to be confused with the ignition timing which is only setting when a spark plug fires.

The timing pointer may be wrongly set - check where TDC 1A really is and then install the camshafts with the notch pointing upwards using the camshaft tool. Do not rely on the pointer alone.

kind regards

Donc cale en place, le repère 1 A vilebrequin doit être face au repère 0 sur la plaque moteur, c est bien ça ? Et ensuite seulement synchroniser l allumage . Le repère 1A face a 0 correspond bien au pmh , ou il faut vérifier ?
Merci Mr Marek

Yes, the timing plate should read 0 degrees when the 1A cylinder is at top dead centre (“1A TDC”), but the timing plate may be wrongly set, so you should check.

Take a look at threads titled “How to find tdc” or “How to verify 1a is at tdc” or just search for “1a tdc” and then make sure you set the plate to 0 after you have verified you are at TDC on cylinder 1A.

Then can you fit the camshafts, turn the engine forwards manually so the chain is tensioned and then verify that the cam tool fits the notches in the camshafts.

Then later set the distributor static ignition timing and verify your timing using a timing light.

kind regards

Merci Marek pour vos explications.

Bonjour Mr Marek, pouvez vous m indiquer le type d huile a utiliser pour la boîte de vitesse , et quelle contenance après vidange?

Dexron III will be fine.
I think you need about 10lt for an oil snd filter change (TH400)…