How to Fix an Intake Leak on Your C8 Corvette

How to Fix Exhaust Leaks

Dealing with exhaust leaks on your 2020 Chevrolet Corvette can be frustrating. An exhaust leak can lead to reduced performance and other issues. One owner noted the importance of finding even small leaks: "I wish I had purchased the smoke unit earlier to troubleshoot evap issues. The owners manual to the unit I purchased also says you can use it to find exhaust leaks" (Varilux). This guide provides steps on diagnosing and fixing exhaust leaks.

Symptoms

Exhaust leaks can present themselves in a few different ways, making them sometimes difficult to pinpoint. One common symptom is a noticeable decrease in engine performance. You might experience a loss of power, especially during acceleration. This is because the engine isn't maintaining optimal combustion, leading to reduced efficiency.

Another symptom is an unusual or louder-than-normal exhaust sound. The sound can range from a hissing or ticking noise, especially when the engine is cold, to a more pronounced roar or rumble as the leak gets worse. The location of the leak can also affect the type of sound you hear. It's crucial to pay attention to any changes in the exhaust note of your truck.

You might also notice a smell of exhaust fumes inside the cabin of the vehicle. This is particularly dangerous as exhaust fumes contain carbon monoxide, which is a poisonous gas. If you smell exhaust inside the car, address it immediately. Check for any visible signs of leaks around the exhaust manifold, pipes, and muffler.

Finally, while not directly related to exhaust valves, some owners looking for exhaust leaks found loose connections in the exhaust system itself. As one owner reported: "Got under it and tightened every clamp I could on the ARH long system" (R3DRUM. While this might not be the valve itself, it's a related area to inspect.

Most Likely Cause

Based on owner reports, the primary cause of perceived exhaust issues, specifically related to components that affect exhaust flow, is often an intake leak. While not directly an exhaust valve problem, an intake leak can alter the air-fuel mixture and combustion process, leading to symptoms that might be mistaken for exhaust issues. This imbalance can cause the engine to run less efficiently and produce unusual exhaust sounds.

How to Diagnose

To diagnose an intake leak (which can mimic exhaust problems) on your vehicle, follow these steps:

1. Visual Inspection: Begin by visually inspecting the intake manifold and its surrounding components. Look for any cracks, loose connections, or damaged gaskets.

2. Smoke Test: A smoke test is an effective way to identify leaks. As suggested by one owner: "I wish I had purchased the smoke unit earlier to troubleshoot evap issues. The owners manual to the unit I purchased also says you can use it to find exhaust leaks" (Varilux. Connect a smoke machine to the intake system and observe where smoke escapes. This will pinpoint the location of the leak.

3. Spray Test: With the engine running, spray a small amount of carburetor cleaner or starting fluid around the intake manifold gaskets and vacuum lines. Listen for any changes in the engine's idle speed. If the idle increases, it indicates that the cleaner is being sucked into the engine through a leak.

4. Check Vacuum Lines: Inspect all vacuum lines connected to the intake manifold for cracks, breaks, or loose connections. Replace any damaged or worn-out lines.

Tools required:

• Smoke machine (optional, but highly recommended)
• Carburetor cleaner or starting fluid
• Spray bottle
• Wrench set
• Screwdriver set

Step-by-Step Fix

If you've identified an intake leak, here's a step-by-step guide to fix it:

1. Gather Parts and Tools: Ensure you have the necessary replacement parts, such as intake manifold gaskets, vacuum lines, and any other components that were found to be damaged during the diagnosis. Also, gather the required tools, including wrenches, sockets, screwdrivers, and a torque wrench.
2. Remove Intake Components: Disconnect any electrical connectors and vacuum lines attached to the intake manifold. Carefully remove the throttle body (TB). You can consider upgrading components like the TB as part of this process, as one owner mentioned using an "ls2 tb" (Z.06), but ensure compatibility.
3. Remove Intake Manifold: Unbolt the intake manifold from the engine. Be careful not to damage any sensors or components during removal. Lift the manifold off the engine and set it aside.
4. Clean Mating Surfaces: Thoroughly clean the mating surfaces on both the intake manifold and the engine block. Remove any old gasket material or debris to ensure a proper seal with the new gasket.
5. Install New Gaskets: Install the new intake manifold gaskets onto the engine block. Make sure the gaskets are properly aligned and seated.
6. Reinstall Intake Manifold: Carefully reinstall the intake manifold onto the engine block. Align the bolt holes and tighten the bolts to the manufacturer's specified torque. Use a torque wrench to ensure proper tightness.
7. Reinstall Components: Reattach any electrical connectors, vacuum lines, and the throttle body to the intake manifold. Ensure all connections are secure and properly seated.
8. Test for Leaks: Start the engine and listen for any signs of leaks. You can use the spray test method described earlier to check for leaks around the intake manifold gaskets and vacuum lines.
9. Tighten Exhaust Clamps: As a preventative measure, check and tighten all exhaust clamps as another owner suggested when working on their exhaust system (R3DRUM.
10. Verify Repair: After completing the repair, take the vehicle for a test drive to ensure the issue has been resolved and the engine is running smoothly.

Parts and Tools Needed

• Intake manifold gasket (Check with your local Chevrolet dealer for the exact part number based on your engine type)
• Vacuum lines (if needed)
• Throttle body gasket (if removed)
• Wrench set
• Socket set
• Screwdriver set
• Torque wrench
• Carburetor cleaner or starting fluid (for testing)
• Shop towels

Real Owner Costs

The cost to fix an intake leak can vary depending on whether you choose to do it yourself or take it to a professional mechanic.

DIY:

• Intake manifold gasket: $20 - $50
• Vacuum lines (if needed): $10 - $20
• Carburetor cleaner: $5 - $10
• Total DIY Cost: $35 - $80

Professional Mechanic:

• Labor: $200 - $500 (depending on the shop rate and complexity of the job)
• Parts: $50 - $100
• Total Professional Cost: $250 - $600

Keep in mind that these are estimates, and the actual cost may vary depending on your location and the specific repair shop you choose.

As one owner encountered a significant cost for a related repair (though not specifically exhaust valves): "Dealer did confirm it was a bearing, just would not repair it and is trying to force me into buying an entirely new TT assembly - $9500 labor/parts" (R3DRUM. While not directly applicable to an intake leak, it highlights that some repairs can be quite expensive.

Prevention

Preventing intake leaks involves regular maintenance and inspections. Here are some tips to help prevent this issue on your vehicle:

• Regular Inspections: Regularly inspect the intake manifold and vacuum lines for any signs of damage or wear. Look for cracks, leaks, or loose connections.
• Proper Torque: When reinstalling the intake manifold or any related components, always use a torque wrench to tighten the bolts to the manufacturer's specified torque. Overtightening or undertightening bolts can lead to leaks.
• Quality Parts: Use high-quality replacement parts, such as intake manifold gaskets and vacuum lines, from reputable brands. Avoid using cheap or inferior parts, as they may not provide a proper seal and can fail prematurely.
• Professional Maintenance: Have your vehicle professionally maintained by a qualified mechanic. They can perform regular inspections and identify potential issues before they become major problems.

What Owners Say

Real experiences from CHEVROLET owners:

Success Stories

"Quote: Originally Posted by knewblewkorvette Even after hitting it with my purse , I still couldn't get my 98's cap to loosen. So out came the channel locks, that did the trick. if swinging my purse harder don't work, an oil filter wrench will Quote: Originally Posted by Kubs I washed it today." — _zebra (source)

"So out came the channel locks, that did the trick. if swinging my purse harder don't work, an oil filter wrench will Quote: Originally Posted by Kubs I washed it today." — _zebra (source)

Owner Experiences

"Turns out after repeated order mishaps I have three of the RPI rear plate covers now. Electron blue, painted/cleared black, and out of nowhere long after the order issues were resolved a third one showed up this weekend which is a flat black." — Tusc (source)

"I don't trust someone flashing dyno sheets at me without knowing firm details, but it claims higher curve across the mean vs our usual setups. It is done in Titanium and domestically so the price is ridiculous." — Tusc (source)

"Aside from the synchro going the transmission which was removed had always felt as heavy as it apparently was. This 70k mile drop-in feels brand new by comparison and if someone told me it had been upgraded I would be inclined to believe them based on the range of improvement." — Tusc (source)

Lessons Learned

⚠️ "I wish I had purchased the smoke unit earlier to troubleshoot evap issues. The owners manual to the unit I purchased also says you can use it to find exhaust leaks." — Varilux (source)

⚠️ "I still have OEM LS7 head castings and a friend's OEM LS7 block in my car. Not much else is OEM there except my TB, intake manifold, and exhaust manifolds." — Z.06 (source)

⚠️ "I assume it was to light up the corny logo filler plate thingie that wad glued to the tub. That is an option for sure but ultimately I still have more than enough room to just keep shortening the rod portion of the hangers." — Mr. Black (source)

Pro Tips from Owners

💡 "They look very similar to motorcycle exhausts. I would love to swap them for a quad tip with an electronic baffle so I can have quiet stop and go driving and loud spirited driving (far away from the law and my neighbors)." — Swollgineer (source)

💡 "I would love to swap them for a quad tip with an electronic baffle so I can have quiet stop and go driving and loud spirited driving (far away from the law and my neighbors)." — Swollgineer (source)

Real Repair Costs

"Got under it and tightened every clamp I could on the ARH long system. Dealer did confirm it was a bearing, just would not repair it and is trying to force me into buying an entirely new TT assembly - $9500 labor/parts Found a good shop near me, going to buy the RPM bearing repair kit and go that route." — R3DRUM (source)

"Dealer did confirm it was a bearing, just would not repair it and is trying to force me into buying an entirely new TT assembly - $9500 labor/parts Found a good shop near me, going to buy the RPM bearing repair kit and go that route." — R3DRUM (source)

"For now, it's looking like a very well spent $100. Here's a link to the particular device I purchased- it's pretty simple to operate and comes with everything you need (whoops, looks like it was a little more than 100- still a good buy IMO at $129- I went for the version with a built in air pump). https://www.amazon.com/dp/B0B2JV8YDP?psc=1&ref=ppx_yo2ov_dt_b_product_details https://www.amazon.com/dp/B0B2JV8YDP?psc=1&ref=ppx_yo2ov_dt_b_product_details" — Varilux (source)

FAQ

Q: How long does it take to fix an intake leak?

A: The time it takes to fix an intake leak can vary depending on your experience and the complexity of the job. If you're a DIY enthusiast, it may take you anywhere from 2 to 5 hours. A professional mechanic can typically complete the job in 2 to 4 hours.

Q: Can I drive with an intake leak?

A: While it may be possible to drive with an intake leak, it's not recommended. An intake leak can cause reduced engine performance, poor fuel economy, and potential damage to other engine components. It's best to address the issue as soon as possible.

Q: Is this a common issue on the 2020 Chevrolet Corvette?

A: Intake leaks can occur on any vehicle, including the 2020 Chevrolet Corvette. However, it's not necessarily a widespread or common issue. Regular maintenance and inspections can help prevent intake leaks.

Q: DIY vs mechanic - what's recommended?

A: Whether you should attempt a DIY repair or take your vehicle to a mechanic depends on your skills, experience, and comfort level. If you're confident in your abilities and have the necessary tools, you may be able to save money by doing it yourself. However, if you're not comfortable working on your vehicle or if the job seems too complex, it's best to seek professional help.