Common high-mileage C6 Corvette problems:
- While harmonic balancer problems can strike almost any C6 Corvette, timing chain tensioner issues are limited to LS3 cars while Z06s’ rod bearings and valve guides can fail
- The C6’s alternator and airbag light problems are easily rectified, but late-model fuel pump/sending unit flaws are trickier
- You might not have a problem with how later C6 Corvettes’ magnetorheological shocks work, but the repair bills are another matter
Although the C5 Corvette Z06 is still an incredible sports car bargain, the C6 is surprisingly affordable now, too. And for the most part, the 2005-2013 Corvette is a reliable used sports car. However, it’s not immune to the ravages of time or mileage, nor was it perfect from the get-go. Thus, C6 Corvettes often suffer from one or multiple common problems.
Keep in mind that used Corvettes are still used cars. So, they’ll inevitably experience things like interior rattles, worn-out shifter components, and tired shocks, e.g., common high-mileage used car issues. As such, the guide below focuses on problems that are specific to C6 Corvettes and/or strike them more commonly than other used cars.
Wobbling harmonic balancers are one of the most common C6 Corvette problems
There’s an LS V8 at the heart of every C6 Corvette. 2005-2007 models have the 6.0-liter LS2 while 2008-2013 ones have the 6.2-liter LS3. The C6 Z06, meanwhile, has the 7.0-liter LS7 and the ZR1 has the supercharged 6.2-liter LS9. And while the LS is a stout engine overall, it’s not without its faults.
One of the most common engine-related problems, particularly on base C6 Corvettes, is harmonic balancer failure, PistonHeads says. The harmonic balancer/damper is kind of like a shock absorber for your crankshaft. As your crankshaft spins, the force of combustion causes it to flex slightly back and forth. Unchecked, this could throw off timing, or worse, cause resonance that could shake the engine apart. Luckily, the harmonic balancer absorbs (damps) these vibrations before this happens.
But while the C6 Corvette’s harmonic balancer does its job, it doesn’t always do it for long. Over time, the outer weighted ring starts ‘walking’ down the center mount closer to the engine block. And if you don’t catch it in time, you might be in for a broken oil pump, crankshaft, or even block.
However, a good pre-purchase inspection often catches wobbly balancers before they completely fail. And more durable one-piece replacement balancers are readily available.
C6 Corvettes with LS3 V8s can develop timing chain tensioner problems
Although the later LS3-powered C6 Corvettes are generally more desirable than the LS2 ones, they’re not without some problems.
On the plus side, the C6 Corvette has a timing chain, which lasts longer and doesn’t stretch as much as a timing belt. However, that only applies to chains with functional tensioners. And unfortunately, the LS3’s timing chain tensioners are prone to failure, PH reports. If they fail, not only can that damage the chain, but it could severely damage the rest of the engine.
Fortunately, although replacing a timing chain and its supporting parts isn’t easy or cheap, upgraded replacements exist. So, although C6 Corvette chain tensioner problems shouldn’t be ignored, they’re fixable.
Not all C6 Corvette Z06s have valve guide problems, but many owners still worry
With upgraded brakes, a magnesium front subframe, and that high-revving 505-hp LS7, the C6 Z06 is an enthusiast favorite for track and street duty. But while it can generally handle extreme driving, this extreme C6 Corvette also has some engine problems. Chief among them are the valve guide issues that led to an attempted class-action lawsuit.
The LS7 V8 can rev to 7100 rpm partially because it has titanium intake valves and con rods, which is significant for an early-2000s American engine. However, over time, some Z06 owners noticed their LS7s’ valve guides wearing down extremely quickly. And that’s when the real trouble started.
Initially, worn valve guides just cause excess valvetrain noise, which is annoying but not necessarily harmful. But over time, this lets oil into the combustion chamber, where it burns, fouls spark plugs, causes misfires, and even damages the catalytic converter. And if the guides wear down even further, you’ll end up with broken valves and a broken engine, Road & Track says.
GM eventually traced these issues back to faulty cylinder heads from a single supplier. Reportedly, only some 2008-2011 C6 Z06s were affected. And by now, these cars should have stronger replacement heads. Still, this is one C6 Corvette problem worth keeping in mind when you’re scheduling a PPI.
Some C6 Corvette Z06s have problems with their rod bearings
Worn valve guides might be a worrisome C6 Corvette Z06 issue, but the LS7 had some other problems. And right behind worn valve guides are rod bearing failures. Yet in this case, it’s seemingly not because of a flaw.
Until 2012, LS7 V8s had tri-metal rod bearings composed of steel, bronze, and lead. But because of EU regulations, GM had to replace them with bi-metal aluminum-and-steel ones for the 2012 model year. From a health perspective, less lead is a good thing. But lead is good for engine longevity because it can safely trap engine debris; aluminum can’t. As a result, the newer rod bearings wore out faster than the earlier tri-metal ones.
There is some good news, though. Firstly, engine oil analysis usually catches C6 Corvette Z06 rod bearing wear before it causes additional problems. Secondly, rod bearing failure appears to mostly strike track-driven and modified Z06s that don’t switch to higher oil grades or track-specific formulas. And finally, if rod bearing failure truly worries you, aftermarket tri-metal bearings are available.
High-mileage C6 Corvettes sometimes have alternator problems
The previous C6 Corvette problems were engine-specific, but there’s another issue that can crop up regardless of your LS choice. And that’s alternator failure.
Admittedly, alternator failure can strike almost any older used car, not just a Corvette. However, high-mileage C6 alternators fail not just because of age, but because of engine heat, PH reports. And even if they don’t fail, they sometimes don’t charge the battery properly.
Luckily, you can access the alternator fairly easily in a C6 Corvette. So, even if you don’t feel confident in replacing it yourself, it’s not a particularly lengthy or difficult repair for a trained mechanic. And aftermarket suppliers like Billet Tech offer performance-minded replacement alternators with improved cooling.
A lit-up airbag light often has a simple fix
Even if they haven’t always used Takata products, Corvettes have sometimes been part of GM airbag recalls. As of this writing, the C6 isn’t part of any open airbag recalls. But high-mileage C6 Corvettes can sometimes develop airbag-related problems. Or rather, airbag light-related problems.
Now, an airbag warning light usually means that there’s a problem with your airbags. However, that’s not necessarily the case with some C6s, PH notes. Instead, it could be because one of the wires or electrical connectors underneath the driver’s seat wiggled loose. So, before you schedule an airbag replacement, check underneath your seat.
If your C6 smells like gas, you might have fuel tank issues
These next problems can theoretically happen to any high-mileage C6, but 2007-and-later Corvettes are seemingly more affected. Some late-model C6 owners have reported cracked fuel pumps and/or cracked fuel sending units. And in some cases, the cracks even damaged the fuel tank itself. So, if the C6 you’re looking at smells strongly of gas, you might want to walk away.
Admittedly, these fuel pump issues are repairable. Some were covered as part of GM technical service bulletin #15682, for example. However, if your car wasn’t fixed, the repair requires dropping the fuel tank out of the car, PH explains. It’s doable, but it won’t be cheap.
Look out for Magnetic Ride Control problems on high-mileage C6 Corvettes
As noted earlier, suspension wear is par for the course on high-mileage used cars. So, if your old C6 needs new shocks, that’s not a flaw, that’s part of regular maintenance. However, there is a complication with some C6s you should know about.
In 2009, the C6 ZR1 introduced Magnetic Selective Ride Control with adjustable magnetorheological shocks. They work great, R&T says, stiffening up for corner carving and softening for urban commuting. And starting in 2011, the Z07 Package granted these shocks to Z06s. This eliminated the harsh ride earlier Z06s are known for, hence why these later models are often worth more.
But while these fancy shocks are arguably worth paying more for, they’ll also cost you more when you have to replace them. One of these magnetorheological shocks costs around $300-$400, and that’s not including any extra wiring, sensors, or control modules. So, it’s not uncommon for some C6 owners to install non-magnetic coilovers instead and plug in special ‘simulators’ to shut off the resulting warning lights.
And there you have it: some of the most common high-mileage problems C6 Corvettes face. Although some can be expensive to fix, none of these are necessarily catastrophic deal-breakers. Just make sure to set aside some extra time and money if any strike your C6. Or, if you’re Corvette shopping, pick a less faulty car.
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