Bizzare knocking noise. Defeated me, the mechanic and logic

[MB-BTurbo]

I had a knocking noise coming from the front left side of the car. The garage identified it as an ARB bush. They cleaned it, greased it and put it back on. Knocking stopped for 2 months.

It then came back so I squirted it with silicon grease and it went away for 3 weeks, then came back. Did this a few times until the knocking became more persistent and wouldnt go away with anymore, so I bit the bullet and bought a new bar at £100 plus 3 hourse labour! (no you cant buy the bushes separately for some reason).

After it was done the knocking was still there!!!

It got louder and more frequent than ever, then went away completely except for a very faint rattle over bumps. 1 day later it came back, then went away.

Any ideas please? I have just spent £800 on the starter motor and tyres and cant afford to throw any more trying to work out whats causing it.

 

[John]

I'm surprised you've not driven it off a cliff by now.

You've got incredible patience!

 

[Olivier]

How about the links for the ARB?
Those can knock badly.

 

[moonloops]

If it has suspension control arms, it will be them.. otherwise lower ball joints

 

[GP801]

+1 for anti roll bar drop links. I have had this on various cars in the past and always a pain to spot. Dealer kept insisting there was nothing wrong. They will look fine but still make a noise.

 

[MB-BTurbo]

The mechanic who is very good at what he does said it definitely sounds an ARB noise. The clonk does sound like it I have to admit but it does explain how the noise went away when the bush was lubricated yet when replaced it still makes the noise albeit intermittently.

The links were replaced 6 months ago and if it was them then shouldnt it be just as it was before? Thats the bizarre thing.


I think Im going to ask Swansea if I can put a 12 plate on it. So far in 6 months of ownership it has new suspension up front, shocks, springs, arb, bushes and droplinks all round, new steering column, new calipers, new doors (rust), new starter motor, new tyres, new body panel trim. it has to be the newest old car out there.

 

[Olivier]

The easy way to know if its the links is to take them out and see if there is a knock or not driving carefuly. Secure the antiroll bar first tho...

 

[MB-BTurbo]

Just got back from the garage. He spent 1 1/2 hours taking things apart, lifting it up, taking the drop links off and thoroughly going over it.

After everything we were all left scratching our heads non the wiser. He suggested the most likely cause is the shock absorber and top mount which I think is the most likely cause as well. At £240 though I am thoroughly unimpressed with Mercedes making a car that has needed 2 of these replacing with less than 30,000 miles done.

When I spoke to the Mercedes parts dealer he said, "yeah, they tend to wear now after 4 or 5 years".

Roughly translated; "we sell you substandard cars that are designed to fall to pieces just outside of the warranty so you then have to pay us more money on top of the premium you paid us for buying a quality car like Mercedes, just to put it right again".

 

[MB-BTurbo]

If it has suspension control arms, it will be them.. otherwise lower ball joints

Just curious. How do you know it will be them?

 

[MB-BTurbo]

I think Im going to ask Swansea if I can put a 12 plate on it. So far in 6 months of ownership it has new suspension up front, shocks, springs, arb, bushes and droplinks all round, new steering column, new calipers, new doors (rust), new starter motor, new tyres, new body panel trim. it has to be the newest old car out there.

What do you think my chances are of asking Mercedes for a contribution considering the milage and everything that has gone wrong and the amount spent on it so far?

Steering rack £500 (used)+ 10 hours labour,
Front right shocks - £130 + .5 hour labour,
Top mount - £80
Springs - £100 + 1 hour labour
Caliper, front left - £70 (recon) + .5 hours labour
ARB - £91 + 3 hours labour
Starter motor - £305 + 4 hours labour
Ipod link left front speaker - Fixed myself

Ongoing issues -
rust on tailgate
shock + top mount failure.
Mercedes want another £460 +.5 hours labour

Total - £1736 in parts + 19.5 hours labour.


All 4 doors have been replaced due to rust from the previous owner.
Car is '06 and done 30,000 exactly.

 

[moonloops]

Just curious. How do you know it will be them?

My CLK ate through 3 sets, 2 in my ownership. Just wondered if it could be the same for the OP's car?

 

[MB-BTurbo]

Thanks, I think it sounds too high up for them. It is in the right area but not low enough. The mechanic also tested these for movement and noise and said they were in pretty good nick.

3 sets? Is that normal Mercedes practice or was there any underlying fault?

 

[V12]

Ridiculous case. Drive the car through the dealers window.
Please tell me that your car is an isolated case and this is not common amongst B classes (or other models for that matter)

 

[MB-BTurbo]

When I was researching the B class came out as one of the better Mercedes in terms of reliability. Mercedes are falling further and further down though according to the reliability indexes. As long as they keep making shiny prestigious looking cars people will keep buying them. Their name is cemented so why would they keep making 4mm items that last when they could get away with 3mm items that fail 4 years down the line, raking them in huge servicing £££.

Anyway if I go with my list what do you think they will say regarding a contribution? Is there any chance?

 

[danclyon]

If it helps, my wifes B is rattly as hell. I am utterly unimpressed with it - doubly at the stupid "drop the bonnet from a foot up" mechanism to shut it and total absence of any NVH material on the inside of the bonnet and such a stupid lights setup.

FWIW, when we got it it went back and had all sorts of stuff "sorted" on it - even though it was MB approved (ARB links, track rod ends, glow plugs, new poly-v belt, new this, new that, and that was on TOP of the £1100 service it had before we took it on (B service plus gearbox oil and all the other things the car was asking for!) - and this was from a main dealer too......

I'd go to them with a list personally as that's just shocking - mind you, we've had rust done that MB said not their problem over (it was eventually done at the body-shop that did the accident repair that MB claimed wasn't done at an MB approved body shop.....yet it was!).

Overall, the car looks lovely, but the build quality - good god it's shocking!

D.

 

[grober]

Have you considered worn engine mounts? One reason for the premature suspension component failure of today's cars is the ridiculous wheel / tyre /suspension combinations offered by most upmarket German manufacturers. While fine for thrashing up and down the smooth autobahns they don't seem to cope well with UK's poorly maintained roads. They may look good but owners may well be paying a price with reduced suspension longevity.

More than :bannana:??????????

 

[MB-BTurbo]

Where are the engine mounts? Are they near the top of the shocks?

Ive ordered a new shock and top mount with 20% off as I went in with my list.

Completely agree with the suspension unable to cope with the road conditions.

 

[MB-BTurbo]

If it helps, my wifes B is rattly as hell.

Ive never known a car like it. For me it rattles because things fail, not because they are screwed down loosely or using thin connections etc.

When the (hopefully) shocks are replaced it will be smooth and silent.

£1100 service it had before we took it on (B service plus gearbox oil and all the other things the car was asking for!) - and this was from a main dealer too......

What the heck did it need? I have a 'D' service coming up in 4000 miles. I was expecting £300-£400, not £1000+. For a small family hatch that is nonsense.

 

[grober]

Where are the engine mounts? Are they near the top of the shocks?

Ive ordered a new shock and top mount with 20% off as I went in with my list.

Completely agree with the suspension unable to cope with the road conditions.

ENGINE SUPPORTS AND ATTACHMENT PARTS ENGINE SUSPENSION

 

[MB-BTurbo]

Have you considered worn engine mounts?

Thanks but why might it be them? I have never heard of them failing/making a noise etc. They look like a massive engine out job

My mechanic didnt mention anything about the engine mounts so hoping for the best.