My A35 just diagnosed with the same cylinder head problem. 2020 car with 28K miles. Under warrranty although Mercedes still opted to take on 75% of the cost leaving the warranty to cover the remainder. Does anyone know if the repairs are likely to be carried out with an improved head? Are the later model engines designed with an improvement otherwise I cant see anyone risking owning an A3without anextended warranty which is an additional annual expense.

 

We haven’t seen any reports of A35 FL versions having this problem.

 

The root cause is not the “cylinder head” - the head is the same pre and post replacement.

The root cause failure is one or more of the valves and/or valve guides or seats, but under warranty, M-B will replace the entire cylinder head (and cylinder head gasket obviously).

Out of warranty, a replacement of valves & valve guides is possible.
Unless the owner keeps driving it under the fault conditions to such an extent that the movement/wear of the valve seat ring damages the actual head itself, and other components.


"The valve guide and/or seat ring may wear over time due to increased lateral forces during operation. This could potentially cause combustion misfire for cylinder 1 through 4, resulting in an activation of the check engine Malfunction Indicator Lamp (“MIL”)."

 

The root cause failure is one or more of the valves and/or valve guides or seats,

This is a symptom. What is the cause? As it’s not happening on with the same frequency on other engine variants.

 

Looking at the poll 50% of people who answered have had this issue which seems to indicate a serious underlying floor in that engine. If there are no known occurances with the FL version do you know what updates were made to the engine or are they just newer and defects are not occuring yet. Im back into Mercedes this afternoon to arrange a courtesy vehicle but hey dont seem very knowledgeable about any engine improvements if there are any.

 

I don’t know yet of what MB changes were made to the FL version, if any. But I would hope MB would not put out the FL with a known design fault.

 

Self reporting Polls on forums are statistically flawed.

 

I just got my A35 back from MB Oxford after a cylinder head replacement under warranty after only 28K miles. While the technician replaced the head, worringly he discovered a crack in the timing chain which was also replaced requiring full engine removal also under warranty. It's my first Mercedes and I have to admit my confidence in the vehicle is shot. Not only has it suffered a low mileage serious engine malfunction but there was also a potentially catastrophic mechanical fault in a component designed to last the life of the vehicle. I wont be keeping it unless I can keep a warranty on it which might be difficult. MB paid 75% of the warranty cost despite it being under warranty which to me indicates that the warranty company is pushing back on claims due to the design fault. I'm worried warranties might not be extended or if available will be prohibitively expensive.

 

Look at around 28mins on this video. A good explanation about the engine valve problem.

 

I understand your worries and agree.....

What I will say is "generally" MB warranty is better than most other manufactures...

How do I know?

Over 20 years of motor trade experience, dealing with many technicians, sales and aftersales staff who have worked at various brands.

It's VERY uncommon for an MB made engine to have a common major issue such as the one with the A35 engine types, the good thing about MB is that they cover sequential damage too (I wont go into full details of MB warranty and bore you haha).

Once MB vehicles are out of standard manufacture warranty they give you the option to extend, so this is an option for peace of mine.

I work for an MB dealership, so learn the trend of faults with many model and engine types, the fault you have experienced is really the only known common issue these cars develop, so yeah I agree it shouldn't happen, but it's been resolved,

So if you like the car, try and enjoy it, give it a second chance and see how you get on

 

I work for an MB dealership, so learn the trend of faults with many model and engine types, the fault you have experienced is really the only known common issue these cars develop, so yeah I agree it shouldn't happen, but it's been resolved,

Do you know if MB have done something with designed of the head to solve the problem highlighted in the video.

 

Hi Jason that’s good information. I only bought the car in December so still have 20 months cover on the warranty and a service plan so I’m won’t do anything rash but I’ll definitely extend the warranty unless it’s hugely expensive. The car will still be under 50k by the so fingers crossed.

 

I haven't had a chance to look at the video yet, BUT.....

When opening EPC and looking at the cylinder head there are special notes attached to it stating that the part number fitted from factory is no longer available and to use an alternative part number instead.

Additionally the exhaust valves have had a supersession on the part number also...

So I guess the head and exhaust valves have been modified.

Three years ago MB also released a "KIT" part number:

We would like to make you aware of the creation of a parts kit for the replacement of the cylinder head on M 260 petrol engine. The parts kit comprises of a complete cylinder head, head gasket and intake manifold seals, all other parts for the repair should be ordered separately.

 

Yup - I reported this back in 2022 😂

https://www.aclassclub.co.uk/posts/195443/

 

Look at around 28mins on this video. A good explanation about the engine valve problem.

I watched the video a few days ago

I haven't had a chance to look at the video yet

Don’t bother.

He’s speculating and barking up the wrong tree re the cause of the valve and seat pitting.

M-B have already stated why the problem is occurring in a TIPS.

https://www.aclassclub.co.uk/posts/225337/

Let’s not continue to set hares running by suggesting there’s a problem with the head.

 

😂

A generalised response from Google AI about the perils of a repeated fault following a repair, with zero nuance about the specifics of the M260 engine, nor the difference between a repair carried out by a professional or not, whether it was a quality repair, or just a replacement without looking into further contributory factors etc.


Yes. Agreed. Let’s not give this any further airtime!!! 😂

 

I'm joining the club with a Misfire in Cylinder 1!

2019 PFL
43000
Reg SMxxTHZ
Status: To be recovered from home soon
No warranty

 

I'm joining the club with a Misfire in Cylinder 1!

2019 PFL
43000
Reg SMxxTHZ
Status: To be recovered from home soon
No warranty

Good luck but note from the experience of others that MB have been contributing to the repair.

 

Good luck and please keep us posted.

 

An update regarding our 2019 A35 AMG.

MB Dealership has confirmed a new cylinder head is required and quoted almost £6,000. Despite the vehicle having full MB service history since new and relatively low mileage, they have only offered a discount of 11%.

 

Within the dealership I use there is a warranty and claims manager. They contact MB about GW gestures. Either your dealership contact MB or you should for a GW gesture. Your quote in terms of what you will have to pay is too high compared to what others were achieving.

 

Update regarding Manufacturer contribution for our 2019 A35 AMG:

After initially offering a discount of 11% against a quote of almost £6k to repair the cylinder head, Mercedes have come back via the dealership to offer a 40% goodwill gesture to the repair. Leaving us to pay £3750. As we have only been dealing with a chap from service reception at our local dealer, we will now contact the warranty and claims manager to try to push for more of a contribution from Mercedes.

 

Thanks for the update. Look forward to hearing if you’ll get any more from them.

 

We had a rather curt response from the service manager at our dealer who has informed us that the 40% is full and final contribution and that we have to either pay the 60% balance on the invoice or they will put the car back together as it is and then we would have to pay the diagnostic fee of £4500. And if we do not choose either option by the end of today we will also incur storage charges of £50 per day on top.

 

Shoddy garage behaviour. Contact the MB CEO.