Renewing Chain Tensioner

[and11]

Can anyone drop me any tips on renewing the timeing chan tensioner on 1989 w124 300d? i've just got the haynes manual but not always clear instructions for novice diy in this, unless i'm getting a bit slow on pick up.

 

[eric242340]

Chain Tensioner

Can anyone drop me any tips on renewing the timeing chan tensioner on 1989 w124 300d? i've just got the haynes manual but not always clear instructions for novice diy in this, unless i'm getting a bit slow on pick up.

To be honest this is not a DIY job, the tensioner comes in two pieces and the outer case has to be inserted and tightened first. Now the difficult bit is to insert the inner tensioner. It has a rather large spring and you must ensure the inner tensioner is all the way in before screwing it in place. If you get it wrong, total dissaster will occur. suggest for this one you get an experienced mechanic to do it for you.

 

[and11]

To be honest this is not a DIY job, the tensioner comes in two pieces and the outer case has to be inserted and tightened first. Now the difficult bit is to insert the inner tensioner. It has a rather large spring and you must ensure the inner tensioner is all the way in before screwing it in place. If you get it wrong, total dissaster will occur. suggest for this one you get an experienced mechanic to do it for you.

That's a bit of a downer, as in an earlier thread i started, ' sounds like a bag of nails on tickover ' i was quoted,


The timing chain tensioner can fail,and they do, easy to replace.

Malcolm
__________________

 

[Ian B Walker]

Andy, you have a pm

 

[Stevie A]

Be carefull when doing this job. There are plenty of posts about it. Do a search.

As Eric says, if it is not done right you can destroy a good bit of the engine.

 

[Ian B Walker]

I think we are talking about the 27mm nut tensioner on the outside of the block. Its very easy to do and virtually impossible to cock anything up. Granted if it was the tensioner rails then you are talking a different story. The job should take less than 10 mins to do. Currently doing mine on the 124 coupe (more than once due to first snapped cam and secondly snapped chain, all in the space of a month)

 

[and11]

I think we are talking about the 27mm nut tensioner on the outside of the block. Its very easy to do and virtually impossible to cock anything up. Granted if it was the tensioner rails then you are talking a different story. The job should take less than 10 mins to do. Currently doing mine on the 124 coupe (more than once due to first snapped cam and secondly snapped chain, all in the space of a month)

Thankyou for this advice, obviously the other chaps must be thinking of a different engine from mine. I will post the results when job is completed and if ever over your way will call in Ian, possably with a job i can't manage! Andy.

 

[eric242340]

Renewing the chain tensioner

Be carefull when doing this job. There are plenty of posts about it. Do a search.

As Eric says, if it is not done right you can destroy a good bit of the engine.

Please trust me on this one, ive seen good technicians come to a sticky end and ive had to answer to the boss. They on both occasions got fired. Its not a simple job. These tensioners use a circlip, that can stick and serious engine damage will occur, albeit not straight away. This tensioner dates back to the 126 model and every good Benz mechanic will tell you its not a DIY job. pl ease take care.

 

[eric242340]

That's a bit of a downer, as in an earlier thread i started, ' sounds like a bag of nails on tickover ' i was quoted,


The timing chain tensioner can fail,and they do, easy to replace.

Malcolm
__________________

Sorry Malcolm, but this one has caused me many headaches in the past and as Ive said, qualified tecnicians and not just mechanics have come unstuck with this one. The new tensioners come in one piece, therefore Mercedes has accepted this causes problems.:|

 

[television]

Sorry Malcolm, but this one has caused me many headaches in the past and as Ive said, qualified tecnicians and not just mechanics have come unstuck with this one. The new tensioners come in one piece, therefore Mercedes has accepted this causes problems.:|

Dissagree completely ,it could not be more simple, there are no circlips in use on them, must be of some cheap hong kong manufacture that you use.

You just have to fill it with oil,using a press and screw it in.


Malcolm

 

[eric242340]

Dissagree completely ,it could not be more simple, there are no circlips in use on them, must be of some cheap hong kong manufacture that you use.

You just have to fill it with oil,using a press and screw it in.


Malcolm

Hi Malcom, I think were talking about completely different tensioners here, as ive said there are to types the old two piece and the new one piece. could you clarify which one you mean. I know your very good at finding links, perhaps you could post a picture? Thanks eric

 

[television]

Hi Malcom, I think were talking about completely different tensioners here, as ive said there are to types the old two piece and the new one piece. could you clarify which one you mean. I know your very good at finding links, perhaps you could post a picture? Thanks eric

Hello Eric, this picture shows both,item 89 though MB say that the mod was 84 both types are shown here on the 124 that followed the car at the start of this thread.

http://www.detali.ru/cat/oem_mb2.as...GM=717.433&CT=M&cat=19T&SID=05&SGR=015&SGN=01

Regards Malcolm

 

[television]

I have a feeling that there was once a surplus stock of these things, or some coppies floating around, none of the dates marry up as to when it was changed. though it is on the Russian site as from 91. MB say 84.

Malcolm

 

[kth286]

All

I absolutely agree with eric242340 that there is a technique to use to fit the tensioner or you WILL break the camshaft as has happened to Ian B Walker.

A chap on one of the forums last year complained of the strange wining noise at the front of his engine after having the tensioner replaced (by a non Merc
garage).

I knew immediately that the tensioner had not been fitted in the correct sequence and recommended he NOT use the car until it was sorted by an experienced guy.

He did state a few days later that he used the car and broke the camshaft.

Camshafts are hollow.

If the tensioner internals are not pushed all the way through the outer jacket and then reinserted in the correct direction, the tensioner will be far too tight and either snap the chain or the camshaft as per Ian B Walker.

If you are going to get someone else fit it for you, ALWAYS ALWAYS ask if they have done one like this before and to describe to you if there is anything special that they need to do. If they do not know what you mean - find someone else.

Regards

 

[television]

All

I absolutely agree with eric242340 that there is a technique to use to fit the tensioner or you WILL break the camshaft as has happened to Ian B Walker.

A chap on one of the forums last year complained of the strange wining noise at the front of his engine after having the tensioner replaced (by a non Merc
garage).

I knew immediately that the tensioner had not been fitted in the correct sequence and recommended he NOT use the car until it was sorted by an experienced guy.

He did state a few days later that he used the car and broke the camshaft.

Camshafts are hollow.

If the tensioner internals are not pushed all the way through the outer jacket and then reinserted in the correct direction, the tensioner will be far too tight and either snap the chain or the camshaft as per Ian B Walker.

If you are going to get someone else fit it for you, ALWAYS ALWAYS ask if they have done one like this before and to describe to you if there is anything special that they need to do. If they do not know what you mean - find someone else.

Regards

The new type come ready to fit and just screw in, maybe there are some old type floating around or patten coppies. there is nothing mentioned in the MB workshop manuals other than fill it with oil first and scew it in. they come pre set to the minimum adjustment, and only release on the application of the oil presure.

So with two types there will be conflicts in the postings

malcolm

 

[kth286]

Malcolm

The original poster on this thread has a car with just one camshaft so your Russian picture is not the correct one.

Saying that, the principle of the chain tensioner is correct.

Your picture shows the complete tensioner assembled and it shows the same tensioner with all it's component parts.

Regards

 

[kth286]

To my knowledge there is no update for tensioners for the W124 range of engines.

 

[television]

Malcolm

The original poster on this thread has a car with just one camshaft so your Russian picture is not the correct one.

Saying that, the principle of the chain tensioner is correct.

Your picture shows the complete tensioner assembled and it shows the same tensioner with all it's component parts.

Regards

The new version only comes assembled,it make no difference as to the picture ,as there is only the one supplied and this comes pre set ready to fit.

If people are going to skimp on a job by taking the old one to bits and then refit, then maybe you will be in trouble.

This thread started by asking how easy is it to fit a new tensioner, so you gat a new tensioner,fill it with oil and screw it in. These things will screw in lightly mainly with finger pressure, if you have to wind it the whole way with a spanner and its tight then you should not be doing your self.

By the way,the picture is from a 124190 300 diesel.

Malcolm

 

[Stircrazy]

Is it easy to cross thread it then?

Difficult to access?

 

[television]

Is it easy to cross thread it then?

Difficult to access?

No it is not easy to cross thread it, it will go in finger tight for the best part.

You are screwing into an alli timing cover, and if the job is as clean as it should be it will be finger tight. It is normal procedure to release the tension on the tensioner side.

Malcolm