C class 200k cam chain gone at 100,000 miles

[zenman63]

The wives car has had this rattle for some time, I thorough it was the heat shields but just the other day with a mechanical clatter, its stopped, only on the drive.
I did think the starter bendix had gone as it sounded like the engine was not turning over and having pulled it out, and re fitted it we found, its turning the engine just no compression.
So i just pulled the cam cover and the chain between the sprockets is slack and it would appear to have jumped a tooth on the right cam.

So question is do the valves hit the pistons?
What sort of job is the chain, amazed is not a duplex chain!

 

[WG M-B]

I try and get my customers to change them at 70/80k. Really sorry to hear you have had this issue. It's been covered on here many times over.
And yes you will have bent valves

 

[zenman63]

Bent valves is just not good news, so question is, head off and re build or swap the engine for a known good one, could it have done a piston?
I had no idea theses where so poor.
Or salvage for parts.
How can you be sure it's bent the valves?

 

[shorty]

I had the chain jump on my 200k , it jumped 2 teeth on inlet cam I didnt bend any valves . It might be worth a punt to fit a new chain and see if the car runs

 

[joe]

I had the chain jump on my 200k , it jumped 2 teeth on inlet cam I didnt bend any valves . It might be worth a punt to fit a new chain and see if the car runs

Same on mine, at about 60k.......... no valve damage.


Good Luck
Joe

 

[zenman63]

This just turns over with no compression and there was a mechanical clatter first.
I could do with a inspection camera to go down the plug holes and see it any impact has happened.

 

[zenman63]

This is all good news, how can I pull the ends of the chain together without the tool?
And is it easy to see the timing on the sprockets ?

 

[markjay]

In 1997 a belt (not chain) snapped on a 1.8L Diesel Ford I was driving - bent valves, so new engine was needed.

In 2001 the belt pulley broke on my 2.5L Vauxhall - the belt jumped a few teeth but no engine or valve damage, new belt and pulley kit sorted this out.

Both engines above are normally prone to valve damage in these circumstances.

So.... maybe yes, maybe no, depends if you are lucky.

But if the valves are bent then a second-hand engine might be the better option.

 

[zenman63]

Just looked at the sprockets and it's defiantly jumped but how do I re time them?

 

[shorty]

Is there any damaged teeth ? if so the sprocket will need changing , and there not cheap , over 700 euro each .
There is marks on the ends of the cams that align with the head , there's no need for locking tools , the tensioner is accessed by removing the alternator and popping out a rubber bung .

 

[zenman63]

The sprockets look fine but you can lift the chain 30mm between them so the tension must be shot.
can you tell me more about theses timing marks?

 

[WG M-B]

If it hasn't bent valves you are very lucky.
I have seen these crack pistons when they let go!!!

The timing marks are straight forward on the backside of the gears ( just straight lines )
If you are going to re time the engine then you will need a chain and tensioner. You will also need a riveting tool for the chain and a tool to lock the cams.
The alternator needs to be removed along with a core plug to gain access to the tensioner (which is spring loaded )
Then you will need to do a compression test

 

[zenman63]

Thanks for the replies, no point in a used engine as they will be the same.
I can pull this apart and fit new valves with some help on here.
Is MB the best for parts or is there a better chain?

 

[E55BOF]

"This just turns over with no compression"

If the engine turns over but there is no compression on ANY of the cylinders you have bent valves, without question (unless you have cracked pistons....). Unless you can use a borescope, you won't know whether there is any significant piston damage until you take the head off.

 

[zenman63]

Just about to make a start pulling the head off, I will be back with the results.

 

[def90cars]

Just about to make a start pulling the head off, I will be back with the results.

Interesting quote!

Keep us updated, all good info.

 

[zenman63]

Well all good so far, lol what a job, its so complex, just have to get the crank nut undone, 27mm so need a socket for that.
The air box! no way but its out, its just so tight with everything around it.
Just starting wis and epc to see if I have missed any bolts, I need the front cover off.
The sump has a sound deadening felt cover, all nicely engineered just a shame about the chain!
I can set the timing just with slipping the chain so I guess its sprockets as well.
Its a good 45deg out and more.

 

[zenman63]

Well its off, around 6 hours work so far.
All the inlet valves are bent.
So nicely engineered to be let down with a poor chain.

 

[ricardo62]

im sure mercedes used to have a telly ad ending with the quote meticulous engineering ???

 

[WG M-B]

I would change the valve guides while its off...