Rattle at 2000 rpm

[penaz]

Hi,

I'm new to forum - so reassuring reading about other peoples woes!

Anyone offer me quick advice. I have a c220 cdi 1999 and when engine is cold and I accelerate upto 2000rpm i get a distinct rattle from engine. When I accelerate through it it disappears only to return at 2000rpm. After about a 15 minute journey it goes away. My prestige car specialist mechanic has listened to it and says that I can either put up with it or have something done with tappets - about £500 worth. Any ideas?

 

[Brian WH]

Hi,

I'm new to forum - so reassuring reading about other peoples woes!

Anyone offer me quick advice. I have a c220 cdi 1999 and when engine is cold and I accelerate upto 2000rpm i get a distinct rattle from engine. When I accelerate through it it disappears only to return at 2000rpm. After about a 15 minute journey it goes away. My prestige car specialist mechanic has listened to it and says that I can either put up with it or have something done with tappets - about £500 worth. Any ideas?

When was the engine oil changed last, as new oil will quieten the engine down, unless the tappet gaps are excessive.

What is he going to do for £500? Renew or adjust the tappets?????

 

[Dieselman]

It sounds more combustion orientated to me.

Firstly run some injector cleaner through with the diesel and if that doesn't fix it have the engine oil flushed with proper flushing oil, then replaced.

If it still does it, it wont, have the injectors tested.

 

[Glideman]

Don't think you can adjust the tappets, they don't have them. Are they not hydraulic?

 

[pluggers]

Is it definatly coming from the engine itself or around the engine? Could be the exhaust manifold heatshield rattling or maybe the heatshield around the bulkhead touching on something.

 

[penaz]

Thanks for replies, yes it's definately the engine, a rapid rattling sound (like my old 170k miles vw passat 1.9 diesel had all the time) when at 2000rpm. Like I say, if you put your foot down it goes away only to return as above. I've just had oil change service (castrol magnatek) not flushed and I put diesel injector cleaner in with this tank of diesel. So, I take it it's nothing tooo serious???????

 

[Ian B Walker]

Don't think you can adjust the tappets, they don't have them. Are they not hydraulic?

Adjustment of Hydraulic Tappets is done with shims so I am told and £500 is the going price I am sorry to say. But as has been posted changing the oil and flushing the system could make all the difference

 

[guydewdney]

ehhhhhhhhhhh? 'adjustment of hydraulic tappets is done with shims????????????'

what???????

thats the whole point of HT - there are no shims... someones leading you up the path...

first thing i'd do is get a pole (old car jack pole is good, or jemmy / wrecking bar) rev engine to 2K (FROM THE PEDAL not the engine bay..) and GENTLY pry against things like the exhaust manifold to see if you can get it to stop rattling. there are quite a few heat shields etc that can come loose.

its v difficult to diagnose a noise...

be careful - lots of spinning nasty things

 

[Karl]

I had a similar problem with my W210 E300D earlier this year, It makes an expensive sounding noise that comes and goes with engine speed. It turned out to be a faulty fanbelt adjustment damper.

It is easy to diagnose, the damper is a very small shock absorber on the front of the engine.
I carefully wedged a long flat bar between the adjuster and the engine block to stop the adjuster moving and got a friend to rev the engine. The noise stopped.
Replacement requires a little inginuity or you will have to take out the radiator and fan assemly to gain acces to the bottom bolt.

 

[Ian B Walker]

ehhhhhhhhhhh? 'adjustment of hydraulic tappets is done with shims????????????'

what???????

thats the whole point of HT - there are no shims... someones leading you up the path...

Must be the Nasty Haynes manual again as it states that the shims are located in the buckets. page 2b 11 para 24

 

[penaz]

All taken on board, however, if loose heat shield etc, why would it disappear as engine warms?

 

[Satch]

All taken on board, however, if loose heat shield etc, why would it disappear as engine warms?

Metal expands when hot and that may be enough to take up any play or simply change the dynamics of the item vibrating.

 

[penaz]

Thanks for advice, can you just help me out as to why the engines only noisy when cold and particularly at 2000rpm? Is it something to do with the time it takes for the oil to get circulating?

 

[Dieselman]

Thanks for advice, can you just help me out as to why the engines only noisy when cold and particularly at 2000rpm? Is it something to do with the time it takes for the oil to get circulating?

Still sounds like combustion rattle, especially when cold.
Have you tried any injector cleaner / cetane improver yet?

 

[penaz]

yes mate I tried it two fill ups ago. That was a fuel additive to clean the injectors. Is it worth getting oil out again, and flushing or is it more likely to be injectors? Why does it only happen when cold..infuriating - great after 10-15 mins.

 

[Glideman]

Also try bleeding the fuel system. Maybe an air lock.

 

[Dieselman]

Also try bleeding the fuel system. Maybe an air lock.

Any diesel with a leak off back to the tank is self bleeding.

 

[Dieselman]

Why does it only happen when cold..infuriating - great after 10-15 mins.

You've answered your own problem, it's just down to the cold weather making combustion not as complete. In addition the ECU is advancing the timing which then gives a rougher, but more powerful combustion.

If it quietens as the engin warms then stop bothering about it, it's the way it's supposed to be.

There is an issue with dribbling injectors and that will cause rattle but normally it doesn't go away and it causes smoke also.
You could have your dealer or a locel diesel specialist check the injectors for dribbleing and leak off pressure.

 

[Stratman]

Thanks for advice, can you just help me out as to why the engines only noisy when cold and particularly at 2000rpm? Is it something to do with the time it takes for the oil to get circulating?

Metals expand when they heat up, so perhaps when the bits that rattle get longer/fatter, they no longer have the room to vibrate.

As to why 2000 rpm, that is just the resonant frequency of the bits that rattle.

 

[penaz]

Thanks guys, you've put my mind at rest between you!!!