Hi All. On returning home a few days ago my '03 CL600 decided to cut out whilst I was at the lights. The car started right up however there was an initially strong small of burning oil. Sure enough when I pulled over and popped the hood, there was a small amount of smoke coming from the engine. I then noticed that I had no coolant .
Pulled the codes using DAS and saw multiple cylinder misfires(4, 6, 7, 9, 11)and Oil temp implausible code(no other engine faults).
Attempted to find source of coolant leak and when re-filling, found water pouring out of area behind serp belt so safe to say i was very low on coolant however I always keep an eye on the temp when driving and was nominal during the trip(still to dig into exact source)
Decided to inspect plugs so removed all. Found some oil at the base of some of the plugs(worst plug was #1 which did not report misfire) however no oil on thread or tips of plugs. No evidence of any coil pack or insulator damage.
Completed compression test of all cylinders and all ~160+/-10 so seems fine.
Only obvious source of the oil found was cracked oil fill cap which may explain why plug 1 was worst for oil in the plug housing.
Checked vac hoses and replaced some lines that looked a little on the brittle side.
Put everything back together and cleared codes and started up. Again, on initial startup, engine sounds fine however then starts shutting down cylinders and becomes very rough idle, with cylinder 1 now showing misfire code in addition to those above.
Ran DAS diagnostics counting the errors on each cylinder when idle and all cylinders except #5 showing some level of faults(5 to 15).
I was going to start to swap plugs and injectors next however with all cylinders showing faults, looking for any advice on next steps, or additional diagnostics I could use the DAS for to help. Please let me know if there is critical info I am missing.

Thanks in advance, Chris

 

The v12 models are infamous for issues with the coil packs, I’ve never owned a v12 but I hear about it often enough

the water behind the serpentine belt sort of sounds like a failing water pump to me, your other problems almost make it sound like a blown head gasket? This may be a tricky one

 

Thanks for the quick reply.

Yes, I replaced a coil pack a few months after I had purchased the car a few years ago, however the symptoms then were a consistent and specific couple of cylinders on one bank misfiring. In this case I have both banks affected which I would think make the coil packs less likely. I also upgraded the voltage transformer to the higher temp rated version.
I will be inspecting inside the cylinders at the weekend using one of the mobile endoscopes so will hopefully provide some additional insight

 

Any evidence of coolant in the oil, or vice versa? It might not show this early, but they make test strips so that you can tell for sure. Might be able to find them locally. Keep us updated on the fix

 

03 to 06 v12 engines are bullet proof. Aside from the coil packs and hydraulic suspension fitting. These bad boys are good. That being said, only if you had air in your cooling system would the head gasket be gone. Now once air is introduced, it is not so easy to get it out without special equipment

 

Once you taste the real torque..... sorry but it is more addictive than HP

 

So dam true "No replacement for displacement"

 

Coil pack I am going guess.Common on these 600's

 

I think it would still start with a bad pack. Not with both bad though.