Merc M273 V8 Idler Gear Wear/Failure, what's the worst that could happen?

Wife has an 07 CLS550, 123k miles, CEL has been on for abouth a month. While I was doing her oil change, I ran the codes.  P0015, P0016, P0017. Basically codes related to cam timing. Evidently this code combination is a kiss of death. There was a batch of M272 v6s and M273 v8s with improperly hardened timing gears that E36 M3 the bed. My motor sits in the engine code range that is affected. On the v6s, these also drive a balance shaft, on the 8 it's merely an idler gear. When the wear becomes bad enough to the point the variable cam phasers can't compensate, it throws the code. I have to check one the cam alignment through the sensor holes, but I'm 96% sure it's hosed. 

Here's the kicker, to get to this stupid part, it's a full engine out, everything off the front end of the motor to access . 35-40 hours of book time. I haven't made calls yet, but figure 3-4k, almost half retail at this point. JY motors seems to be in the $1500-2000 range. MB did get sued, and there was a class action settlement. At my age/miles, I'm beyond the extensions though. 

At this point I can:

A: Fix it, either do the idler gear or JY engine 

B: Trade it. For kicks, I did a carvana trade, with CEL deduction and a dent, the offer was $300 (-1950 for the CEL, -350 for the dent). Maybe dealers will be more generous. 

C: Ignore it. I'm trying to find out what the worst case scenario of just driving it is. The worst I can really find, is accelarated timing chain guide wear, and possibly if you wear those out, wearing into the block. That seems a ways off. I notice a slight loss of power at lower revs from the cam retardation, she doesn't. Gas mileage is maybe a smidge worse? No misfires or rough idle or other drivability issues. I'll have an issue with NYS inspection when the time comes because it gets plugged into the OBD port, but I'll worry about that later.

WWGRMD?

How quick does it throw the CEL when you wipe it?

Wipe code, do drive cycle, run like hell to Carmax to dump the turd before the CEL lights up again.

In reply to slefain :

Throws it immediately on start. I'm inclined to just send it. I don't think it'll get worse. And honestly drivability is barely affected. I have to push the gas a few degrees more. Famous last words.

Drive it til it breaks or until the inspection runs out, then part it out. Here's your inspiration: https://grassrootsmotorsports.com/forum/off-topic-discussion/parting-out-cars-for-profit-and-maybe-fun-2012-mercedes-c300-edition/145788/page1/

LS swap! (runs, ducks)

fatallightning said:

In reply to slefain :

Throws it immediately on start. I'm inclined to just send it. I don't think it'll get worse. And honestly drivability is barely affected. I have to push the gas a few degrees more. Famous last words.

It really depends on how long until the next stage happens, where the timing chain slips and you wreck all the valves.

If I liked the car and wanted to keep it I'd probably try DIYing the repair -- from what you said it sounds like it's lots of time, but nothing really hard.

In reply to codrus :

Lots and lot of time, and specialty tools. High chance of me mucking it up. 

That's what I'm trying to ascertain, I don't know if its physically possible for the timing chain to slip. The tensioner takes up the slack of the worn out idler gear, which pulls the cams out of phase relative to each other. Once they're out of phase, I don't think they can get "more" out of phase. And I don't think it can physically get slack enough to jump a tooth or cause enough of an out of phase to make valve/piston contact.  

In reply to fatallightning :

If the tensioner can not take up the slack anymore, the chain can jump.

Usually this will happen on a cold start after the oil drools out of the tensioner and phasers.  That clatter on a cold start before oil pressure builds is all the slack in the phasers hammering the stops.  That hammering is what jumps the chain.

In reply to Knurled. :

Possible. Right now the tensioner only has to make up for the small amount of reduced chain travel path created by the worn idler. No ill noises yet, clatter will be something I'll keep an ear out for. 

Methinks that since its cheaper to throw in a used a motor out of the bum idler gear range instead of RnRing the existing one, might as well drive it till she's really smoked. Which may never happen. Only out the tow/AAA wait at that point.

In reply to fatallightning :

Years ago when the LT1 Corvette was still in production, one of the fellow readers of rec.autos.driving (USENET, I did say it was years ago...) decided to see how long the serpentine belt would last.  He reasoned that the water pump was cam driven, so he wouldn't hurt the engine.  He could drive without power steering and air conditioning, and the battery had enough reserve capacity to get him to safety.  And he kept a belt and the required tools in the car.

(120k, by the way, although it started looking like hell much earlier than that)