230ce 124 coupe chain tentioner 1990

[p.sainsbury]

just changed the head gasket and all is fine except i noticed some material has come off the tentioner and i think the chain is to tight? i removed the plunger to take off the cam sprocket and put it back in again? has the plunger got to be set? and is there an easier way of replacing the tentioner without removing the sump? the chain is the double row type any ideas thanx

 

[Will]

Hi,

I presume you mean the tensioning rail that the chain passes though as opposed to the actual tensioner (the piece that you fit from the outside of the engine)

What I think has probably happened is that the tensioner wasn't assembled properly before fitting and it caused the sliding rail to snap. You must re-set the plunger when you refit the tensioner.

Quite a pain to replace the rail as you'll need to remove the sump as you say, the front timing cover etc, fair amount of labour there unfortunately. Might as well change all of the rails whilst it's all apart, and probably worth doing a new chain and tensioner this time too I reckon.

Good luck

Will

 

[p.sainsbury]

thanks for that but i mean the actual chain tensioner and what has to be done to set the plunger? thanks for your help,phil.

 

[Will]

Hi Phil,

I'm trying to picture it as I haven't got one in front of me obviously.

I think the middle part ratchets out, to sort of self-adjust, and maintain pressure on the rail even when there is no oil pressure, this is the revised type btw - the early tensioners used on some M102 engines used to cause the chain to run loose sometimes on start up as they relied more on oil pressure I think.

Basically, I think you need to fit the outer part of the tensioner into the block, then refit the plunger, spring and then the middle bolt that holds it all together.

If you try to screw it into the block in one piece, the plunger will push all the way out and means that you'll be putting too much tension on the sliding tensioning rail, which is what might have made it snap.

Hope this helps

Will

 

[Will]

Hi John,

This is an old picture of one from one of my cars.

Does this look similar to yours, I think this is the later type.

The allen bolt in the middle comes out to remove the plunger and spring for refitting. The inside of the body is grooved to allow the plunger to ratchet outwards.

Will

 

[kth286]

p.sainsbury

You should not run the engine at all until you have removed reset the chain tensioner.

Otherwise the tight chain WILL break the hollow camshaft - very expensive.

The tensioner has to be dismantled and the inner parts pushed through the outer body and out the back of the tensioner body.

The outer body (only) then has to be screwed into the engine, and then the inner parts have to be pushed into the body and screwed into the body.

The ratchet mechanism only allows the inner parts to go one way ie. towards the chain.

Get a Haynes manual if you are not sure, to avoid expensive damage to the engine.