u/KENOZIZ

TL;DR: Did a manual carbon cleaning on my 105k-mile Kia Lambda II V6. Stripped two head bolts during reassembly due to Kia's notoriously soft aluminum blocks. Rescued it with an aftermarket thread insert kit. Installed an aftermarket oil catch can to help minimize future fouling.

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At 105k miles, I took on a DIY carbon cleaning on my 2015 Kia Sedona SXL. GDI engines like the Lambda II V6 get notoriously filthy with carbon buildup on the valve stems, piston crowns, and fuel injector tips (my injector tips were pretty clean though).

Because these deposits harden to the point where spray-in products like Seafoam or CRC are entirely ineffective, I had to resort to manual scraping within extremely tight confines. It was such a miserable, tedious experience that it genuinely has me having second thoughts about ever buying another GDI vehicle. The only good news was that my 7,500-mile oil change frequency kept the bottom end completely free of oil sludge, but I'll be reducing it to every 5K miles going forward.

Unfortunately, the real nightmare started during reassembly: two of my cylinder head bolts completely stripped out.

At first, I blamed myself, but after digging into the forums, I found out these engines are plagued with incredibly soft aluminum blocks and shallow factory bolt holes. Several owners have reported head bolts backing out completely on their own over time, leading to blown head gaskets.

I talked to a Kia parts manager (who was a former service advisor), and his official diagnosis was that I needed a total engine swap. I refused to accept that. Instead, I tracked down a Huhn NS300L kit, which allowed me to carefully bore out larger holes in the block and install high-quality steel thread inserts. The fix is incredibly solid and should easily outlast the remaining life of the vehicle. If you end up dealing with this same headache, look into Kia's Warranty Extension Program (WTY039). I submitted a reimbursement claim for the thread kit and related parts about three weeks ago. Their autoresponder says it can take up to 60 days to hear back, so I'm just playing the waiting game now, but it's worth a shot if you're paying out of pocket to fix their soft block issues.

With the carbon cleared and the engine successfully reassembled, I installed an oil catch can to help minimize future fouling. However, I completely ignored the manufacturer's placement guide.

Most aftermarket instructions tell you to mount these highly conductive aluminum cans out in the open on a cold firewall or fender well. If you do this, the cold metal walls act as a passive condenser, dropping the hot blow-by gases below their dew point. However, this results in a canister that rapidly fills with a massive volume of milky, watery sludge that you have to constantly drain.

Instead, I custom-routed my lines deep into a hot dead-air pocket located right next to the engine block and the upper radiator hose. By using the engine's own radiant thermal energy to keep the aluminum canister walls very hot, water vapor from combustion is prevented from condensing. It stays in a gaseous state and passes cleanly out to be burned off as steam, so only heavy oil fractions get trapped.

I just pulled the canister for its first check at 140 miles, and the results are flawless: pure, dark, viscous oil with a heavy fuel smell, and no watery emulsion or yellow sludge at the bottom.

If I ever buy another GDI car, an oil catch can will be the first modification I install.

Recently performed some long overdue DIY maintenance on a neglected 2012 TSX Sportwagon with 67k miles. It has been garage-kept during 14 years of ownership, averaging less than 5k miles per year. Although it's exclusively used 93 octane gasoline, the only maintenance that was previously done was annual synthetic oil changes.

Some interesting observations:

• Original spark plugs looked relatively good (replaced)
• Piston crowns had remarkably little carbon buildup (thankfully it's port and not direct injected)
• PCV valve looked barely used and had very little residue when swabbing it out with a Q-tip (replaced)
• Radiator and heater hoses seemed to be in good shape despite the age (replaced)
• Coolant was never changed until now, but was still a vibrant blue when replaced
• ATF was dark brown and never changed before, but after 3 back-to-back 'drain and fills" the transmission still shifts smoothly
• Brake fluid was never changed or topped off before, but the level was to the brim of the master cylinder cover probably from moisture absorption over time. The TSX experienced a mushy brake pedal when braking into a moderate bump, but would go away after pumping the brakes several times. Previously thought it was a VSA/ABS module or master cylinder gone bad, but performing a flush and actuating the ABS solenoids with a two-way scan tool during the flush fixed the problem.
• Car battery would usually last 2.5-3 years at most due to parasitic drain from HFL module. Unplugged the HFL and upgraded to the V6's larger battery size but it needed a larger holding bracket to accommodate.

If you're driving a 2nd generation (2009-2014) TSX and find yourself replacing the battery every 2-3 years, you're not alone. A common culprit is a faulty HandsFreeLink (HFL) Bluetooth module causing a parasitic battery drain. Unfortunately, dealerships often don't acknowledge this specific module as a widespread issue for this generation.

The Problem: The faulty HFL module doesn't fully shut down, slowly draining your battery even when the car is off. Replacing the module is expensive, and there's no guarantee the new one won't eventually fail the same way. Ignoring it can potentially put extra strain on your alternator over time, leading to another costly repair.

The Solution: Disconnect the Module

Since finding clear instructions specific to our TSX was tough, I figured I'd share my experience disconnecting it. It's simpler than you might think and doesn't require removing major console components. You essentially access it from the passenger footwell:

1. Access the Panel: In the passenger footwell, look up under the glove box area. You'll see a black plastic panel/cover.
2. Remove Panel: Gently but firmly pull this panel straight down. It's held in by clips. No tools should be needed to remove it, just careful pulling.
3. Locate Module: Look up into the space revealed. You should see a black rectangular module (the HFL unit) with a wiring harness plugged into it.
4. Disconnect Harness: Press the release tab on the wiring connector and pull it straight out from the module.
5. Reattach Panel: This can be the trickiest part. Get your head down low so you're eye-level with the clip locations. Carefully align the panel's clips with their corresponding slots in the dashboard structure and push firmly until they snap back into place.

Consequences & Alternatives:

• Loss of Factory Bluetooth: Disconnecting the module will disable the built-in Acura HandsFreeLink system. You won't be able to make/receive calls or potentially stream audio via the factory Bluetooth system using the steering wheel or console buttons for that system, but you still have the AUX input within the center console storage area.
• Aftermarket Solution (GROM Audio): If you still want Bluetooth and modern features (and have the factory Technology Package), consider an adapter like those from GROM Audio (e.g., VLine). These integrate with the factory screen and do allow you to retain steering wheel and console button controls for navigating Android Auto or Apple CarPlay. It uses the existing screen, so no touchscreen capability is added, but it modernizes the infotainment significantly. (Full disclosure: I haven't installed one yet, but it's on my upgrade list based on research).

Disconnecting the HFL is a free fix for the battery drain. Hope this helps someone else avoid the dead battery headache and save some money!