M271 Evi - E200CGI knocking sound

[janekdam]

Hi experts,

Any chance anyone had similar knocking sound on their M271 engine and got it sorted?
The car is on 92k miles, it is 5g automatic, had new brake vacum pump and line fitted 2 weeks ago and new timing chain with all necessary equipment supposedly changed at 77k miles by the previous owner. I don't have any paperwork evidence that timing chain was changed but I believe the previous owner as there are some marks on the engine - like old oil leak stain from the top of the engine.

You can listen to the sound here

There is no knocking sound at the cold start - I have another video that I can upload if you want to prove it. There is no knocking sound at low RPM only in that one range - when going over it up the revs or down - I would say approx 3k RPM. I noticed this sound last week but from the inside I thought it was more like a sound of a chain scraping over a plastic cover somewhere, but with the bonnet up it sounds completely different.

Any help or idea what or where to check is greaty appreciated.

All the best!

 

[ernieh]

Hi experts,

Any chance anyone had similar knocking sound on their M271 engine and got it sorted?
The car is on 92k miles, it is 5g automatic, had new brake vacum pump and line fitted 2 weeks ago and new timing chain with all necessary equipment supposedly changed at 77k miles by the previous owner. I don't have any paperwork evidence that timing chain was changed but I believe the previous owner as there are some marks on the engine - like old oil leak stain from the top of the engine.

You can listen to the sound here

There is no knocking sound at the cold start - I have another video that I can upload if you want to prove it. There is no knocking sound at low RPM only in that one range - when going over it up the revs or down - I would say approx 3k RPM. I noticed this sound last week but from the inside I thought it was more like a sound of a chain scraping over a plastic cover somewhere, but with the bonnet up it sounds completely different.

Any help or idea what or where to check is greaty appreciated.

All the best!

It's a bit difficult to identify the source from the video, but if it was valve-gear related, you might be able to pinpoint it using a large screwdriver as a stethoscope. First, though I'd be disconnecting the ancillary drive belt to see if it disappears, and then checking for play in the various ancillaries like tensioner, alternator, etc.

I'll be honest, though, it doesn't sound good!

Ernie

 

[malcolm E53 AMG]

Does sound like big end knock - hope not but better to get an educated opinion as soon as you can

 

[ajlsl600]

Interview the oil filter. Look any white copper metal ( you need to cut it open then open paper flutes, n look) .I wash filter paper in petrol and pour the petrol thru a clean white cloth. View the build up, if any, if no metal u unlikely to hav fd b end or main. I have seen siezed small ends before Then put manual oil press guage see cold idle and warm idle. Modern oil press lights just tell u when it's already fd up. If nothing seen and oil press over 2 bar hot. ConsiderTrying a Mexican tune up.

 

[janekdam]

Many thanks for your interest and information! Malcolm I am not sure what do you mean by the big end knock? Can you please explain?

As for ancillary belt, there is a squeak coming from there that I investigated last weekend and identified that two top idler pulleys are rough to move and the pulley on the tensioner was not great either, I ordered them new with the new belt and will be replacing that when parts arrive, probably over the weekend. I already changed alternator pulley as this was rough as hell.
I only have the car for over a month now and I am doing all the maintenance to it as the service history for the cat is official till 60k miles but then it is patchy and only words, no hard evidence.

As for the car it starts without problems, it drives well, accelerates well and no errors on the dash.

I changed oil on it like two weeks ago and I am always checking the oil filter for anything obvious but I could not see anything unusual. Same in the drained oil, nothing unusual. But I will get another filter and change it and test it to see if there is any metal there.
The car had a problem with vacuum pump when I bought it so I ordered a new one and I installed it, this is when I noticed a bit of sludge in the oil where it enters the vacuum pump and this is the only unusual thing that so far I noticed on the car. Because of that I used an engine flush before the oil change.

To be honest I don't know if the knock was there before the oil change or not, I rather drive like Capitan Slow than Clarkson, but I noticed the sound like last week when car shift down when overtaking. From the inside of the cat it sounded more like a chain scraping on a plastic, and I forgot about it until yesterday when I remembered to check it. I was still using the car daily with no problems.

So I will change the aux belt and pulleys and check the filter, all this probably this week. In the meantime I will look for an oil pressure gauge and I will report back to you with any findings.

Again, thanks a lot for suggestions and ideas!

 

[janekdam]

Hi again,

Now you got me worried about my engine... I was thinking overnight and trying to better understand the situation.

Did you mean that the problem may be like in this video around 3:20?

I can't clearly see on that video but would looking at the cylinder with a camera give me some indication if it is damaged? Or trying to rock it gently with a screwdriver through the sparkplug holes?

 

[ajlsl600]

Don't panic. The process I described is one that has fair chance of showing up an unlikely, but possible issue, rule that out and move on. Meantime continue to keep looking simpler issues. A long screwdriver held up against various components and putting Yr ear to top of screwdriver and casings can often lead to the source. Advise on removing belt to see if noise goes is also good. You referred to some kind of engine knocking. Hence my 1st post. Be methodical.

 

[malcolm E53 AMG]

This is what a worn bottom end sounds like ie, failing piston rod bearings on the crankshaft

 

[janekdam]

Thanks for your help and information, unfortunately I think it is the worst case scenario. I removed the aux belt and the knocking was still there, then I removed the oil filter and from far away I could see debris and metal flakes and a lot of glitter in the oil....

Can you please advise me on what is the best course of action in this situation? Scrapping the car, repairing engine, swapping engine? I don't know what the options are and what the costs are for different options...

 

[ajlsl600]

Some of that don't look good. And that's after a recent filter change, right? You still have that filter?, if so do same if not , 4 me wud be sump off, examine bearings, and oil pump. Ballache but if u run it ur likely to really do some damage. If not already
.