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AMG A35 - New Cylinder Head Please

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#403 · (Edited)
I have the A250 registered in July 2020 with 18k miles, and today as I was planting my foot the car juddered and went into limp mode. It felt as if the engine was misfiring, and would struggle to accelerate from a standstill. Pulled over to one side and restarted the car and the issue went away.
Got home to check for engine fault codes with a generic obd scanner and I'm currently seeing P0304 (misfire on cylinder 4) and P0300 (random multiple cylinders misfire) as pending.
I'm just about out of warranty with Mercedes but luckily still have an extended warranty from the (non-Mercedes) dealer I got the car from.
Do the symptoms sound like a bad cylinder head? Or is it too soon to say? I've noticed that most people have had the issue with cylinders 2 and 3
 
#404 ·
Regardless I would get it straight over to the dealer and say that’s what it seems to be and take it from there.
 
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#405 ·
Addil said:
I have the A250 registered in July 2020 with 18k miles, and today as I was planting my foot the car juddered and went into limp mode. It felt as if the engine was misfiring, and would struggle to accelerate from a standstill. Pulled over to one side and restarted the car and the issue went away.
Got home to check for engine fault codes with a generic obd scanner and I'm currently seeing P0304 (misfire on cylinder 4) and P0300 (random multiple cylinders misfire) as pending.
I'm just about out of warranty with Mercedes but luckily still have an extended warranty from the (non-Mercedes) dealer I got the car from.
Do the symptoms sound like a bad cylinder head? Or is it too soon to say? I've noticed that most people have had the issue with cylinders 2 and 3
Click to expand...
Yes, to me it sounds like the fabled cylinder head issue. Although mine manifested itself on #2, #1 and #3 were also misfiring at a leaser extent.
 
#407 · (Edited)
What a great but very unfortunate and frustrating thread. So much great information regardless.

I was possibly looking to make the jump from a Golf R to an A35 (2021 reg), but now I'm not so sure.
What has the general outcome been after the cylinder head has been replaced/fixed?
Is there lasting damage to other parts or a potential for reoccurrence, or is time still to tell?

EDIT: Also, does the A45 have the same issue?
 
#408 ·
alexcannas said:
Get them to do a cylinder compression test. That is the best way to diagnose the problem.
Click to expand...
Dropped off my car at the dealer this morning to investigate the juddering. Just got a call from them saying the compression on cilinder 3 and 4 are off.

Cilinder head replacement needed. Luckily I’m covered. 🙏🏻
 
#412 ·
J03 said:
What a great but very unfortunate and frustrating thread. So much great information regardless.

I was possibly looking to make the jump from a Golf R to an A35 (2021 reg), but now I'm not so sure.
What has the general outcome been after the cylinder head has been replaced/fixed?
Is there lasting damage to other parts or a potential for reoccurrence, or is time still to tell?

EDIT: Also, does the A45 have the same issue?
Click to expand...
The A45s has a different two litre engine but read the tuning thread as many of us post lockdowns consider it overheats even in UK summer temperatures. But we do not seem to suffer from the same engine problem.
 
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#413 ·
Forrester said:
The A45s has a different two litre engine but read the tuning thread as many of us post lockdowns consider it overheats even in UK summer temperatures. But we do not seem to suffer from the same engine problem.
Click to expand...
Thank you very much for the info. I'll checkout the tuning thread. I assume the A45 is remedied by an upgraded intercooler?
 
#415 ·
This is exactly my thought. And if they replace it with the new type of head from the Facelift A-Class for example? I believe to remember some post stating that the new head they replace it with has a different part number (revision).
 
#416 ·
Ah, that's really good to know.

It would be good if Mercedes changed the cylinder head type on all cars from 2023 (for example) and made a statement. At least then everyone would know where they stand and what they're buying. But, I think that's a lot to ask given the price of the current revision would then drop considerably, also being bad for owners. Tough situation.
 
#417 · (Edited)
LoadmasterNLD said:
This is exactly my thought. And if they replace it with the new type of head from the Facelift A-Class for example? I believe to remember some post stating that the new head they replace it with has a different part number (revision).
Click to expand...
I think it was @veeeight who mentioned it, about some parts having a different part number for cars after Nov 2021.

"The only info I have is that Exhaust Valve (x8) A2640530200 was fitted on the production line up to Nov 2021, thereafter Exhaust Valve (x8) A2640531200. "

post #207

Edit: managed to find the post
 
#418 ·
BlackAnt said:
I think it was @veeeight who mentioned it, about some parts having a different part number for cars after Nov 2021.

"The only info I have is that Exhaust Valve (x8) A2640530200 was fitted on the production line up to Nov 2021, thereafter Exhaust Valve (x8) A2640531200. "

post #207

Edit: managed to find the post
Click to expand...
Thank you! (y)
Not all heroes wear capes!... Unless you do, in which case, more power to you. 🦸‍♂️
 
#419 ·
J03 said:
Thank you! (y)
Not all heroes wear capes!... Unless you do, in which case, more power to you. [emoji3133]
Click to expand...
[emoji23][emoji23][emoji23]

About a month ago or so, one A35 had this issue and was fixed at the service center, under warranty.

A friend did some digging, and found this info regarding that car. Which is exactly as what was said.

Image
 
#420 ·
878 said:
I’m hoping this too.. at least the replacement heads will be better in theory if this is the case. Really didn’t expect my brake pads to outlast my head....
Click to expand...
My A35 is a 70 plate with 22k and I noticed a light knocking noise on idle, and a very slight hesitation when pulling away slowly. It is in with Mercedes now and apparently a compression check revealed 3 cylinders affected. Same as the rest a new head is being fitted. Very dissappointing really as I do not think that Mercedes know why! So it could re-occur
 
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