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

[mrmb]

Yes, I have change the timing chain tensioner myself. You have to take out the Air Filter box to get the access to the tensioner which is behind it on the left side of the engine. There are two torx srews I think T20 if I am not mistaken. One of them is a bit difficult to get out but it can be done.

It sounds as valve tappers.

 

[Submariner1]

It seems to be idling at about 550-600 rpm. If you increase the speed to estimate 700-750 the shaking virtually stops. And by 800 rpm its rock solid.
Rev up to 2,000 rpm and its still rock solid.

The odd thing is I can push the top of the engine and it moves back and forth fairly easily.

Its difficult to tell but at its worst its moving back and forward about 3mm at the top of the engine.

I tried the AC on cold hot and off, made no difference to the noise or the shaking.

 

[Submariner1]

Yes, I have change the timing chain tensioner myself. You have to take out the Air Filter box to get the access to the tensioner which is behind it on the left side of the engine. There are two torx srews I think T20 if I am not mistaken. One of them is a bit difficult to get out but it can be done.

It sounds as valve tappers.

Thanks so nothing special like setting the engine to TDC ?

Was it easy to push the new one in ? As you bolted it up. ( I assume its spring tension? ).
Or do you just let the bolts pull it in .


Sorry I didnt understand what you meant by “it sounds as valve tappers”?
Did you mean it just sounds like normal valve tappets? Or it sounded like the valve tappets were faulty?

 

[ajlsl600]

did you note. the rattle ,gone when warm? you origionally suggested noise goes after a few min ?

 

[Craiglxviii]

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

Argh. There is no “designed to fail”.

 

[mrmb]

Thanks so nothing special like setting the engine to TDC ?

Was it easy to push the new one in ? As you bolted it up. ( I assume its spring tension? ).
Or do you just let the bolts pull it in .


Sorry I didnt understand what you meant by “it sounds as valve tappers”?
Did you mean it just sounds like normal valve tappets? Or it sounded like the valve tappets were faulty?

Hey Submariner1,
You do not have to set the engine to TDC. I have checked the WIS when I was doing mine one and nothing was mentioned that the TDC mark needs to be set. In my opinion you can hear valve tappets, they are maybe a bit louder than they should be but I would not worry yet about it. This engine has a very simple design. They have only 8 valves. I have seen similar behaviour when somebody was using oil 10W-40 Semi-Synthetic but you said it you are using 0W-40 Full Synthetic. Maybe try to change the oil first before you will start replacing more expensive parts. Normally timing chain tensioner gives you symtoms at cold engine start up. You will hear a rattle but not like the one you have it. It will be a lot louder and it will sound like a metal thing hitting something.

 

[mattkh]

The odd thing is I can push the top of the engine and it moves back and forth fairly easily.

Has any body checked the engine mounts yet?

 

[mrmb]

I wanted to mention that is well but forgot to do it. On your video it looks like that the engine is shaking more than it should, I compared that to my W168 and it is not shaking as much. Maybe it is a perception from the video itself.

 

[Submariner1]

did you note. the rattle ,gone when warm? you origionally suggested noise goes after a few min ?

Yep thats why I posted the video/sound recording.

To clarify, the nasty rattle / slight drilling sound one can hear in the cabin, goes after a few minutes, and then it sounds like the video.
Personally I dont like the sound the engine has even after the warm up ( i.e. like the video ). To me it still sounds rough!
But as I never drive the car, maybe only move the car in the driveway, perhaps once a year, I honestly cant remember what it sounded like when it was new.
Sounds daft, but when we bought her my company was growing like fury ... wife needed a car and liked this one .. so I just did it.

But even when the engine is warm and the nasty rattle has gone ... the noise this engine makes concerns me. ( btw in the cabin its sounds fine ).

However the local village mechanic said he thought it sounded fine!

So If it doesnt sound nice to you please let me know.

 

[Submariner1]

Argh. There is no “designed to fail”.

correct ... thats pretty much what the oil company scientist said. If you run it in gently ( over 3,000 miles!) , always fully warm her up 85C before using > 2,000 revs and change the oil and filter frequently (5,000 miles) you should pretty much be fine for 100,000 trouble free miles.

 

[Submariner1]

Hey Submariner1,
You do not have to set the engine to TDC. I have checked the WIS when I was doing mine one and nothing was mentioned that the TDC mark needs to be set. In my opinion you can hear valve tappets, they are maybe a bit louder than they should be but I would not worry yet about it. This engine has a very simple design. They have only 8 valves. I have seen similar behaviour when somebody was using oil 10W-40 Semi-Synthetic but you said it you are using 0W-40 Full Synthetic. Maybe try to change the oil first before you will start replacing more expensive parts. Normally timing chain tensioner gives you symtoms at cold engine start up. You will hear a rattle but not like the one you have it. It will be a lot louder and it will sound like a metal thing hitting something.

Thanks MRMB.
Thanks for the detail.
The “real noise that worried me” is not in this video, as the engine was warmed up.
I will try and record it cold this weekend.

As you said the nasty (can we call it “ Timing chain” type) noise is noticeable when its cold, then you hear it. It is louder, and can be heard in the cabin as you drive. That goes after 2 gentle miles.
( in contrast the noise of this engine warm is not noticeable in the cabin .. sounds fine).
It actually sounds a bit like dragging a chain over an aluminium engine cover. Note I have never had an engine problem before, so its just my “perceived” idea of what that would sound like.

The A Class expert in London, said ( before I discovered this) that he disagreed with MBs choice of 0W40, and iho A Classes “did better” with 10W40 but fully synthetic. So your idea of changing oil variety concurrs.
Its interesting that he said A Classes can sound very “tappetty” Using 0W40 ... put in 10W 40 and the customers say it sounds like a new engine.

So I will do that.

 

[Submariner1]

Has any body checked the engine mounts yet?

No, literally noticed it last night.
Will have that checked.

 

[Submariner1]

I wanted to mention that is well but forgot to do it. On your video it looks like that the engine is shaking more than it should, I compared that to my W168 and it is not shaking as much. Maybe it is a perception from the video itself.

Thanks
I will redo the video one cold and one warm version. This time wedging the iPad against a bulkhead.

I did another “warm” version with the iPad and the shaking looked much less than with the iPhone. But a loud builder’s saw (next door) wrecked the sound track!

There was a big perceptive difference i.e. shaking looked less with the iPad.

What should the idle rpm be?
And can it be increased?

Looks like at 550 rpm it shakes, and 650 rpm its much much smoother.

 

[Submariner1]

One guy on UTUbe said some of these tensioners have a one way check valve holding the oil in. If the seal hardens, then they leak. So overnight the tensioner drains down, and on start up doesnt press hard enough against the chain tensioner guide.
Once the oil pressure builds up ( in a few minutes) then they work better.

This does seem to fit my scenario.

Normally I would take LKs advice and remove the polybelt to see if that cures it ( i.e. ruling out all pulleys and ancillaries on that circuit ).
But hell I cant even see the Polybelt? So will leave that to an Indy.

 

[mrmb]

This is exactly what is happening with the chain tensioners :-D However personally I dissagree that 10W-40 will keep the engine running quiter, I think it will be the opposite specially on cold startups with the lower temperatures. 10W-40 is more dense than 0W-40 when it is cold so in the warm phase it will not make a difference as both oils will behave similarly to each other. I think 0W-40 or 5W-40 is making cold engine startup quieter and better so I would stick in with 0W-40 :-D If it rattles at the start up then yes, replace the chain tensioner, I will not be surprised if it will be blocked as mine one was. Chain tensioner in my dad's W168 was half way blocked, it wasn't working. I have no idea how the chain did not jump. Thankfully he wasn't driving long like that. My dad's W168 was using 10W-40 oil earlier on with couple of services but I have noticed that valve tappers specially when it is cold are a bit louder than they should. We have change the oil to 0W-40 and valve tappers sound similar to your one and engine is a lot quiter at the cold startup. I would not be concerned about it as 8 valves engines sound similar to this one. you will always hear this little tapping noise in them.

 

[bembo449]

Been using the same in mine for years.

more money than sense then pal , no A class bar the 45 AMG warrants such a high performance oil , its no better for the car

 

[Submariner1]

This is exactly what is happening with the chain tensioners :-D However personally I dissagree that 10W-40 will keep the engine running quiter, I think it will be the opposite specially on cold startups with the lower temperatures. 10W-40 is more dense than 0W-40 when it is cold so in the warm phase it will not make a difference as both oils will behave similarly to each other. I think 0W-40 or 5W-40 is making cold engine startup quieter and better so I would stick in with 0W-40 :-D If it rattles at the start up then yes, replace the chain tensioner, I will not be surprised if it will be blocked as mine one was. Chain tensioner in my dad's W168 was half way blocked, it wasn't working. I have no idea how the chain did not jump. Thankfully he wasn't driving long like that. My dad's W168 was using 10W-40 oil earlier on with couple of services but I have noticed that valve tappers specially when it is cold are a bit louder than they should. We have change the oil to 0W-40 and valve tappers sound similar to your one and engine is a lot quiter at the cold startup. I would not be concerned about it as 8 valves engines sound similar to this one. you will always hear this little tapping noise in them.

 

[Submariner1]

The last 2 “value services” on the A Class
£99 2014
£125 2016
If its below an E Class. You get semi synthetic
Above an E Class and you get fully synthetic.

BUT IF YOU JUST ASK, then you can have MOBIL1 0W40. At No extra charge.

very rarely do I disagree with you, but I reckon Mobil1 0W40 would probably provide better engine protection than the std. Mobil 0W40 semi synthetic.

And in my case, its sensible to ask

 

[mrmb]

This no doubt that Fully Synthetic oil will protect the engine a lot better than Semi-Synthetic oil. Full Synthetic oil has a better flow, doesn't burn as fast as semi synthetic and also it is capable of holding it's spec a lot longer under heavier load.

 

[ajlsl600]

if you have not done so, change the tensioner ,its not big cash, saves a major ball ache and that eliminates that, i will be changing mine anyway, they are a known issue and why wait for it to fail, as said seal is issue goes hard .maybe you can change that.o ring i am led to believe,will look WIS next time it rains too busy as the mo