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

[5439]

I have a broken head bolt on my 37k mile 2008 SL63.

It all started with a "Top up coolant" warning as I was driving up the M1.

Thank God for my MB Tier 1 warranty

 

[RJ C63]

Not good...

 

[developer]

A rare (relatively) but significant event.

I had my head bolts replaced on my previous M156 (2010) when they were doing the cam tensioner rattle under warranty.

£6K in total

I hope they will play ball without question - do keep us posted.

The modified headbolts were introduced at engine number ending 60658 (for any other interested/worried parties).

 

[5439]

MB World forum owners seem to report a few similar problems...

M156 head bolt problems - MBWorld.org Forums

 

[BIRMA]

I wonder what an independent would charge to do the bolt replacement.

 

[5439]

So the story so far...

Saturday afternoon, on the Motorway doing 80 mph. The temp needle is showing around 95c and the indicator has turned Red. The speed indicator has a coolant symbol and the rev counter displays "Top up coolant See Owners Manual"

I was 1 mile from the Service Station at this point, so I stopped at the services and added half a litre of coolant. I then drove home (10 miles) and the light came on again.

The coolant was then filled and the car was then taken to the MB Workshop.

 

[BIRMA]

Did a double check of my water level today, it hasn't changed for nearly a year does that mean I'm in the clear?
It's a bit like the bore scoring issue with Boxsters, mine never had a problem but I wondered if buying the warranty would be a good idea.

 

[Peter DLM]

Did a double check of my water level today, it hasn't changed for nearly a year does that mean I'm in the clear?
It's a bit like the bore scoring issue with Boxsters, mine never had a problem but I wondered if buying the warranty would be a good idea.

May wanna check your engine number per Developers's post.

 

[V8andTurbos]

My facelift C63 comes up with top up coolant warning every few months. Is this something I should be worried about?

 

[5439]

The MB Workshop then pressure tested the M156 overnight. I was then told that the engine had passed the pressure test.

The car was then collected and driven home, 40 minutes later the "Top up coolant See Owners Manual" returned. The car was then returned to the Workshop.

My understanding is that they have now removed the heads and are replacing the bolts and gaskets.

(Please note, I am not a Mechanic and I cannot answer any technical questions)

 

[BIRMA]

The MB Workshop then pressure tested the M156 overnight. I was then told that the engine had passed the pressure test.

The car was then collected and driven home, 40 minutes later the "Top up coolant See Owners Manual" returned. The car was then returned to the Workshop.

My understanding is that they have now removed the heads and are replacing the bolts and gaskets.

(Please note, I am not a Mechanic and I cannot answer any technical questions)

I'll be interested to see what the cost is.

 

[BIRMA]

May wanna check your engine number per Developers's post.

Mine is a 2008 car engine number is before. As I mentioned my Boxster model were subject to bore scoring so many took the warranty. But I never had a problem in my ownership.
What would be worthwhile is getting a price for bolt replacement and weigh that against the cost over a few years of having Tier 1 cover. My next project as it happens.

 

[developer]

Mine is a 2008 car engine number is before. As I mentioned my Boxster model were subject to bore scoring so many took the warranty. But I never had a problem in my ownership.
What would be worthwhile is getting a price for bolt replacement and weigh that against the cost over a few years of having Tier 1 cover. My next project as it happens.

Some guys on here have had ARP studs fitted as a one for one replacement, hence not removing the heads, and went on to have Weistec chargers added on - with no problems that I'm aware of so far.
MSL can do the studs.

Others say you must remove the heads and change the head gasket as it's a "one use" item. My bolt replacement cost £1200 of the £6000 warranty bill, which I paid as it seemed daft not to do them while the cams were out.

 

[Lee C63]

As John states above.
You can install Weistec ARP studs one at a time so the heads don't need to come off.
However using MB "upgraded" bolts the heads would need to come off.

Studs fitted to mine just for peace of mind. When the MB bolts were removed there was quite a bit of corrosion on the neck of the bolt.

 

[BenzedUP]

That's terrible!
Warranty or no warranty that's a known issue with the M156 engine, well early ones at least and MB should cover that regardless! :|

A friend of mine who bought my 2009 SL63 a couple of years ago had the same issue last year at 43K

 

[5439]

I now have the car back (three weeks later)

I have some paperwork for the parts that shows £1200 inc vat...

4x Hexalobular Bol
20x Cylinder Head B
1x Cylinder Gasket
1x Cylinder Head G
32x Valve Tappet
2x Filter Element
8x Shell Helix Ultra
1x Threaded Bolt
1x Thermostat Element
1x Mobil A Freeze
2x Sealing Ring

I am waiting for an answer to how many hours of labour it took.

(All the work is covered under the MB Tier 1 Warranty)

 

[Randed]

I know this is an old post, but has anyone experienced similar issues recently?

I have a 2009 SL63 AMG with only 17,000 miles on it. I baby it and pretty much only drive it in the spring and summer. The top off coolant warning and coolant light just came on and I took it up to my dealer. Dealership just called and said I have coolant in my oil and my head bolts are broken. They want to charge me $9,000 US to take out engine, fix head bolts, and inspect for damage. That price won’t cover any engine damage done. I am beyond upset. My dealership sent me to Mercedes customer service to see if they will help with the cost, but after looking at some posts on this forum, I’m not optimistic. This is the first I had heard of the issue, as I am a new forum member. Incredibly frustrated that Mercedes has had known issues with head bolts and these engines and hasn’t done anything to fix them. Even a cheap car would have an engine that would last 10 years and 17,000 miles. I expect more from Mercedes. Now I'm stuck with a car that should still be worth a lot, but not with a bad engine.

Any tips on getting them to help. I've already mentioned that our family has bought these cars for 40 years, I'm in the market for a new SUV, and will never buy a Mercedes again if this isn't made right, but not sure they care.

 

[oldguy57]

but not sure they care.

Think you've hit the nail on the head there. There seems to be a wide variation in how consumers are treated in the UK and the US, so people's experience over here won't necessarily be the same anyway. Perhaps posting on MB World over there might get you a more accurate idea. The guy with the R63 on there certainly had no joy in the same circumstances despite his best efforts. I really hope it turns out Ok for you but don't hold your breath!

 

[Petrol Pete]

An old post but bluddy hel ! how much was this car new ££ just 9 years and 37 thousand miles ago ? 4K miles per year and it practically blows up !

Shocking. big engines like this are almost never stressed in normal use, my 17 year old 1.6 120K Astra had its weeny neck wrung almost every time I drove it, don't get me started on the 8 or so 'rep mobile' company cars I abused , and guess what ? not one of them suffered major engine failure like this, that is what a broken head bolt is, a major failure.

MB ought to be ashamed .

 

[BIRMA]

An old post but bluddy hel ! how much was this car new ££ just 9 years and 37 thousand miles ago ? 4K miles per year and it practically blows up !

Shocking. big engines like this are almost never stressed in normal use, my 17 year old 1.6 120K Astra had its weeny neck wrung almost every time I drove it, don't get me started on the 8 or so 'rep mobile' company cars I abused , and guess what ? not one of them suffered major engine failure like this, that is what a broken head bolt is, a major failure.

MB ought to be ashamed .

I agree it put me right off my SL63 which I chose above an Aston Martin V8S soft top and Audi R8. Up to the point I heard about the issue I loved everything about the car, but my usual boredom of a car after 12 months kicked in and I sold it. I didn't have any trouble selling it. There is no doubt the SL63 ticks every box for me and without any shadow of doubt if a latish SL65 came up at a good price I'd probably buy it.
And yes MB should be ashamed and re-call them and sort it FOC