A Class making a slight rattle noise on start up, goes away after 2 miles

[Submariner1]

any ideas what this noise could be.

Its particularly noticable on a cold morning start up.
As you drive off their is a slight rattle type noise from the engine as you accellerate. If you back off the throttle it becomes more noticable. If you gently start to accellerate it gets quieter.

After about 2 miles it disapears. And runs normally

Mileage is nearly 60,000.
Oil changed every 5,000 miles (Mobil1 0W40) until last change 9,000 miles ago ... slipped up there!
(but the wife insists their is a missing invoice).
Petrol consumption is normal, coolant level is normal, no milky crap.

I read up and it has one of those pumped type of timing chain tensioners. ( has oil holes you have to line up).

So I wondered if the seals were on the way out. Would that make it provide less tension, until the engine oil pressure had built up in it. And hence after a few miles its silent i.e. the tensioner is working properly?

Likewise if on start up the chain was a bit loose .. hence it rattles, especially when one backs off the throttle i.e. would that slacken the chainuntil you accellerate again.
Or does it not work like that?

Any clues what o look for appreciated, made more difficult as I hardly ever drive it ( maybe move it in the driveway once a year) so I am very unsure what it should sound like.

Wife needs the car for short journeys for the next week so difficult to get it to an Indy.

Advice appreciated ... if it is the timing chain tensioner, thats working but not perfectly ... would driving gently for say another 60 miles damage stuff , i.e. could the chain jump? Etc.

Its not lost any oil, and once the noise goes away drives like before.

Any ideas?

 

[Submariner1]

Has anyone changed one of these timing chain tensioners?
It says in WIS:-
- Undo Coolant expansion tank and move aside with hoses attached.
- Undo 2 bolts pull out
- replace gasket and replace bolts to 8Nm.

Is it that simple ? (Assuming one can get at it?)
Does one have to get the engine in any specific rotational position? I assume not ... as I guess the tensioner thing ( looks like an expanding tube) just pushes the tensioner against the chain?

 

[bembo449]

0w40 in an A-class ?? gulp

 

[area51]

0w40 in an A-class ?? gulp

Been using the same in mine for years.

 

[Flyinspanner]

Is it the poly belt & tensioner?

Around that mileage our A140 was noisy after start up, and for a short time after, until warmed up:- diagnosed as the polybelt so had it, and it’s tensioner changed and all back to normal.

 

[LostKiwi]

Why do people always assume a rattle is timing chain related without doing diagnostic procedures first?
As above, remove serpentine belt and see if the rattle persists. Then using a screwdriver or stethoscope determine exactly where the rattle comes from.

 

[Submariner1]

0w40 in an A-class ?? gulp

i saw some test results on a BMW 3 series with 5,000 oil changes and zero engine wear up to 900,000 mile so thought it might prevent the designed to fail element ... ha ha

 

[Submariner1]

Is it the poly belt & tensioner?

Around that mileage our A140 was noisy after start up, and for a short time after, until warmed up:- diagnosed as the polybelt so had it, and it’s tensioner changed and all back to normal.

Thanks,
I mentally ruled that out as I am pretty sure that was done at about 40,000 miles.
But I will dig through the mountain of service records 16 years ! And check.

It was also a more metalic like ticking/drrr type noise.
That said I will revisit it with a wooden pole to try and locate the source.

The good news is she did take it in for the 55,000 mile service ... so it has had its oil changed every 5,000 miles since birth.

 

[Submariner1]

Why do people always assume a rattle is timing chain related without doing diagnostic procedures first?
As above, remove serpentine belt and see if the rattle persists. Then using a screwdriver or stethoscope determine exactly where the rattle comes from.

Thanks Alistair.
As said above I thought it sounded more mettallic but thats dumb as the poly belt turns metal things.

The hardest part is the cars away all week at wifes work.
And to recreate the sound means bliping the throttle.
And the wife flatly refuses to do anything with the car. 3 minutes is her attention span related to car diagnosis.

A friend came around this weekend to help me, and as we had a glass of wine ... she annouced she was going to Henley with her friend for lunch! And drove off!

The other mare, is it doesnt last long, give it 3 to 5 mins and its running perfectly with no noise. And normally runs fine for the whole day. So I would have to locate the noise very quickly, if not found I would have to abort, leave it overnight without the Polybelt and start again the next day.
Cutting diagnosos time to a dry weekend! ... oh for my garage !

 

[Flyinspanner]

Lump of wood may not be the best diagnostic tool.....try this.

https://www.ebay.co.uk/itm/Auto-Mec...533632&hash=item466b416f9b:g:hqUAAOSwNm5ZtHZ6

 

[mrmb]

On my dad's workhorse :-D W168 A140 we had a ticking noise and the engine oil we use is 5W-40 Mobil. We have replaced the timing chain tensioner as it was faulty but some other ticking noise was left over. Hydraulic Tappers on the valves were causing the tickling. I thinkg this is the right word to use "hydraulic tapper valve"?

 

[Submariner1]

OK Polybelt was changed at 43,915 miles but in 2012.
So thats done 16,300 miles and is 6 years old.
( first one lasted 10 years and 44K miles. )
Can one assume the belt should be OK? I Appreciate it could be some ancillary thing run of it like ac pump water pump etc.

Wife poped in for lunch, and I looked at this engine :-/
Blimey didnt recognise any of the engine parts ...hardly looked like a mercedes engine. More like a bunch of black plastic boxes bolted together than a MB engine.

Couldnt even see the Polybelt?
Even if I had a stethescope I would be hard pressed to know what Part of the engine I was looking at,

TBH the only thing this has in common with a proper Mercedes is the size of the service bills!
Does anyone know much about these engines ?

I was just wondering whether it was worth a punt at £85 to change the chain tensioner? And pray it sounds better.
( verses £20 petrol plus £70 for an Indy to look at it?)

Tried to upload a video of the sound to Photobucket , but I think it was too big, it loaded but then wouldnt run, when I came back to it ... it had disappeared.

 

[Submariner1]

questions I would like to know.

1. Does one have to put the engine at TDC on Compression?
- WIS doesnt indicate this, but then it can often assume you know certain basics have to be done.
- the Haynes manual describes this job as part of replacing the timing chain in situ ... and says one needs to put the engine in TDC ... fine for changing the chain, but if you are just changing the tensioner I assume one does NOT have to do this.

2. On U Tube some tensioners have to be primed, by submersing in oil. Do I have to do this?

3. The Haynes Manual says you have to compress the Tensioner as you tighten it. WIs does not mention this.
Is it just a question of undoing the two bolts .. withdrawing the old one, noting the orientation ref the oil way hole.
And then just inserting the new one, pressing it in as you screw down the bolts to 8NM?

I asked about the priming thing, as squeezing it to prime it; as per some non A Class videos seem to differentiate between those Tensioners, that just expand by Oil pressure, and those with a sort of non return ratchet?

Has anyone on here replaced a petrol A160 timing chain tensioner?

I quickly took it tomthe village garage ( not MB specialist) and on arrival it sounded fine, well it would wouldnt it. :-/
And he said he thought it sounded fine.

F*ck I hate intermittant faults

 

[Submariner1]

On my dad's workhorse :-D W168 A140 we had a ticking noise and the engine oil we use is 5W-40 Mobil. We have replaced the timing chain tensioner as it was faulty but some other ticking noise was left over. Hydraulic Tappers on the valves were causing the tickling. I thinkg this is the right word to use "hydraulic tapper valve"?

Thanks
Did you change the Tensioner yourself?

 

[Submariner1]

Lump of wood may not be the best diagnostic tool.....try this.

https://www.ebay.co.uk/itm/Auto-Mec...533632&hash=item466b416f9b:g:hqUAAOSwNm5ZtHZ6

Thanks
Just ordered one

 

[Submariner1]

Is it the poly belt & tensioner?

Around that mileage our A140 was noisy after start up, and for a short time after, until warmed up:- diagnosed as the polybelt so had it, and it’s tensioner changed and all back to normal.

Thanks FS
Sounds like my symtoms.
Sadly it Looks like they just changed the Polybelt, as there is just one part number.

 

[ajlsl600]

OK Polybelt was changed at 43,915 miles but in 2012.
So thats done 16,300 miles and is 6 years old.
( first one lasted 10 years and 44K miles. )
Can one assume the belt should be OK? I Appreciate it could be some ancillary thing run of it like ac pump water pump etc.

Wife poped in for lunch, and I looked at this engine :-/
Blimey didnt recognise any of the engine parts ...hardly looked like a mercedes engine. More like a bunch of black plastic boxes bolted together than a MB engine.

Couldnt even see the Polybelt?
Even if I had a stethescope I would be hard pressed to know what Part of the engine I was looking at,

TBH the only thing this has in common with a proper Mercedes is the size of the service bills!
Does anyone know much about these engines ?

I was just wondering whether it was worth a punt at £85 to change the chain tensioner? And pray it sounds better.
( verses £20 petrol plus £70 for an Indy to look at it?)

Tried to upload a video of the sound to Photobucket , but I think it was too big, it loaded but then wouldnt run, when I came back to it ... it had disappeared.

poly belt is great fun ,one needs an extra arm, long levered spanner, i made mine. its not great access and some of the pulleys are pretty fidldly to get out,in. it can take a while . they are known to mess up the damper,crank pulley, it would be worth checking.i intend to change my chain and tensioner this summer, far better than waiting for it to be a bigger problem . i just need to find a bike type link as i dont have the riviter and cant kind a non expensive version, i will likely only ever use it once ....

 

[Submariner1]

poly belt is great fun ,one needs an extra arm, long levered spanner, i made mine. its not great access and some of the pulleys are pretty fidldly to get out,in. it can take a while . they are known to mess up the damper,crank pulley, it would be worth checking.i intend to change my chain and tensioner this summer, far better than waiting for it to be a bigger problem . i just need to find a bike type link as i dont have the riviter and cant kind a non expensive version, i will likely only ever use it once ....

How many miles has yours done?

Cant even see it on this one!
Guess its under some plastic cover, must check WIS.

 

[Submariner1]

OOOOppps
Looking at a number of A Classes on UTube, my engine seems smoother and quiter than most.
But looking at my Video the engine seems to be shaking/wobbling back and forth (very evenly) at idle MUCH more than the ones on U tube.

It was never stationary, but it now seems to vibrate back and forth about 3mm
I will check that tonight when she returns.

Whats that .. engine mounts?
Truly beginning to hate the word Mercedes.

 

[Submariner1]

Any comments on the shaking and the rattle type noise ( note this was when the engine is warm so the noise is much better ). Very much appreciated.