63 headbolts: Worst case?

[breeze247]

Just doing some homework at the moment for a car that would see track use.

Alongside my cooling post (largely but not exclusively facelift C63), I was wondering about the headbolts.

What is the preventative fix and the cost? I think it was keeping the heads in situ and replacing with aftermarket ARP or similar.

What is the worst case, e.g. headbolts have gone. Oil loss / overheating and the engine is scrap or simply a couple of £k?

What are the tell tale signs?

Would be good to know. I am aware that this is pretty rare and only affects early VIN numbers but equally these cars are getting old and track use won’t help.

Grateful for thoughts...

 

[andybond]

Have you checked your engine against the affected numbers ?

 

[Felstmiester]

Think!!?? I have read of one case on here of head bolt failure. I know lee on here had some up rated head bolts fitted due to having a charger fitted on his pre facelift. I know when I got mine (pre facelift) it was all over the us forums about the early head bolt issue but wasn’t common in the uk. I remember looking at a post of what engine numbers was effected. Obviously mine was not effected so just got on with buying and driving lol.

 

[Mercy Me]

Think!!?? I have read of one case on here of head bolt failure. I know lee on here had some up rated head bolts fitted due to having a charger fitted on his pre facelift. I know when I got mine (pre facelift) it was all over the us forums about the early head bolt issue but wasn’t common in the uk. I remember looking at a post of what engine numbers was effected. Obviously mine was not effected so just got on with buying and driving lol.

Feedback from several UK based Mercedes specialists suggests that the headbolt failure is rare. I always check the temperature gauge and coolant level on my pre-facelift model but so far no problems!

Weistec / ARP would be the route I would go if this ever becomes a problem in the future. As Lee was seriously uprating the power output on his, it was imo, very sensible to carry out this precautionary work at the same time as the supercharger install, with the inevitable economies of scale.

 

[AMGeed]

Post#13 explains a bit.

SL63 AMG "Top up coolant" Head Bolt Failure on M156 Engine

 

[JDL60]

Met my first person last Sunday who had actually experienced the failure themselves on an SL63
Bill was 7k. Lucky for him covered by warranty

 

[Heller]

What are the tell tale signs for this? I was literally thinking my temperature gauge always sits at about 90 but it sounds and feels extremely hot......as in feels like I can sometimes feel the heat coming off it from inside the car if the window is open....I've had this a few.times on older cars but certainly nothing younger than 8yrs. Is this normal?

 

[andybond]

What are the tell tale signs for this? I was literally thinking my temperature gauge always sits at about 90 but it sounds and feels extremely hot......as in feels like I can sometimes feel the heat coming off it from inside the car if the window is open....I've had this a few.times on older cars but certainly nothing younger than 8yrs. Is this normal?

Yes.
Big block , small engine bay = lots of heat.

 

[Heller]

Ok thanks. And are there cases of the head bolts failing on post 2011 cars? (Sorry to hijack the thread)

 

[JDL60]

Ok thanks. And are there cases of the head bolts failing on post 2011 cars? (Sorry to hijack the thread)

The magic engine number is 060658, those after have less chance of this issue although it’s not unkown even then but very unusual

 

[breeze247]

Have you checked your engine against the affected numbers ?

I haven’t got a car, just looking at the options.

 

[breeze247]

Thanks for the responses and yes, it does look like the bill if it has already happened is a big one.

I’d still be curious to know what the cost of getting the ARPs is and also how to know that the failure hasn’t already happened. Feels like quite a big gamble, particularly if the car is going to see track work.

With the overheating issue, it does suggest to me that the answer is to go for a late pre facelift that has a later engine number. No coupe in that case.

 

[Lee C63]

If you go the ARP stud route they can be changed out one at a time (that's how we did mine) but it does require dedicated tools to lock Camshafts. While this is done it's worthwhile changing out the valve buckets (followers) at the same time....I put SLS ones in.

If you had a headbolt failure you would see coolant loss and occasionally get the top up coolant warning.
There have been quite a few failures but remember it's all engine numbers below a certain number so not just C class.

If I remember correctly it was 500 pounds for the ARP studs (parts)

 

[Mercy Me]

If you go the ARP stud route they can be changed out one at a time (that's how we did mine) but it does require dedicated tools to lock Camshafts. While this is done it's worthwhile changing out the valve buckets (followers) at the same time....I put SLS ones in.

If you had a headbolt failure you would see coolant loss and occasionally get the top up coolant warning.
There have been quite a few failures but remember it's all engine numbers below a certain number so not just C class.

If I remember correctly it was 500 pounds for the ARP studs (parts)

Just to add that if you visit Weistec's website, they do a 'M156 Head Studs and Maintenance Package' which consists of the ARP studs, cam cap bolts, cam phaser bolts and SLS buckets for $2,552 (parts only). It would probably be worthwhile contacting MSL who are an authorised UK dealer for Weistec products, for a parts and labour quote.

 

[Jame5]

My car is a pre-facelift. First sign of failure was low coolant level message. I checked for leaks, none visable. I topped up the coolant and a day later I got the same message. It seemed obvious to me then I had a failure. It went off to Merc and was repaired under warranty. Final bill was under 4K I understand. Coolant temperature will not be your first sign of trouble.

 

[JDL60]

My car is a pre-facelift. First sign of failure was low coolant level message. I checked for leaks, none visable. I topped up the coolant and a day later I got the same message. It seemed obvious to me then I had a failure. It went off to Merc and was repaired under warranty. Final bill was under 4K I understand. Coolant temperature will not be your first sign of trouble.

Are you the SL63 James?

 

[Jame5]

Are you the SL63 James?

I’m not sorry. Speaking to the dealer it does seem a rare problem but more and more are cropping up.