Symptoms of a Failing Intake Manifold Gasket

Don't ignore a bad intake manifold gasket.

Despite their simple constructions, gaskets have one of the toughest jobs of any engine part. Smashed between two pieces of hard plastic or metal, they withstand relentless heat, temperature fluctuations, fluid battering, and frame-rattling vibrations. Until they don’t. 

Just as they do a fantastic job of sealing off engine compartments, they also do an incredible job of frustrating their owners when they go bad, particularly the intake manifold gasket or the head gasket. 

Even a small nick or pinhole can create issues and affect how your vehicle drives.

And although you can’t see the gaskets, you’ll likely know when something is wrong thanks to a number of outward symptoms. Prepare for the worst and learn the tells of a bad intake manifold gasket.

What Is an Intake Manifold?

The intake manifold is the part of an engine that collects and directs air into the cylinders. In addition to distributing air, it also distributes coolant to prevent the car from overheating. They are most often made of metal, but occasionally they are made of treated hard plastic.

What Is an Intake Manifold Gasket And How Does It Work?

An intake manifold gasket is a specifically shaped piece of rubber and/or other materials used to seal the connection between the intake manifold and the engine block. It also keeps the air and fluid directed into the correct chambers.

A service diagram of an Acura Integra intake manifold.
A 1998 Acura Integra’s service manual shows how to remove the intake manifold.

What Are Signs of a Bad Intake Manifold Gasket

These issues are not specific only to bad intake manifold gaskets, but they could indicate the problem.

  • Coolant Leaks

The intake manifold has tiny tubes that run coolant through the engine to keep it cool. The gasket keeps the fluid in those tubes, so if it breaks, fluid could leak out. 

  • Overheating

Similarly, if coolant is escaping the engine block, the car might overheat.

  • Rough Idling

If the gasket cannot contain the air it is directing into the engine, the air/fuel mixture 

  • Car Dies

If the leak is big enough, that rough idle could turn into sputtering, which could turn into dying.

  • Poor Fuel Economy

When the air/fuel mixture is not accurate, you might see a negative difference in your car’s fuel efficiency as your car adjusts. 

  • Check Engine Light

If the air/fuel mixture is off due to an intake manifold gasket leak, it could create misfires, which would throw a check engine error code.

Diagnosing a Bad Intake Manifold Gasket

Technically, the only real way to confirm a bad or damaged intake manifold gasket is to remove the intake manifold and inspect the gasket, but that’s a somewhat involved job for something that might not be broken. If you’ve narrowed down your symptoms and believe you have a bad intake manifold gasket, try using a smoke machine to locate the exact position of the leak.

Replacing a Bad Intake Manifold Gasket

Although intake manifolds are all located in similar general positions, their removals are all unique to the specific car. To access the intake manifold and its gasket, you will need to remove numerous parts, tubes, and wires, likely from above and below the engine. 

If you have experience working on a car and are comfortable removing that much of your engine, then find your service manual and follow the step-by-step instructions. If this sounds like a task equal to running a five-minute mile, you should probably take it to a professional.

 

Car Bible’s Glossary of Related Terms

Welcome to Bible School!

  • Manifold 

A manifold is a pipe that splits into numerous inputs or outputs and vice versa.

  • Exhaust Manifold

 The exhaust manifold collects the exhaust gases from the engine and funnels them into the exhaust system.

  • Engine Block

The engine block, also known as just the block, is the primary piece of metal that makes up the engine. It contains the crankshaft, the cylinders, the pistons, oil, coolant, and dozens of other parts vital to your car’s functionality..  

Your Questions, Our Answers on Intake Manifold Gaskets

Car Bibles’ answers all your burning questions!

Q: Is a Head Gasket And an Intake Manifold Gasket the Same?

A: They are not. Whereas the intake manifold gasket seals the intake manifold to the block, the head gasket seals the cylinder head to the block. 

Q: Should I Use a Sealant on Intake Manifold Gaskets?

A: Some gaskets do require sealant such as RTV upon installation, but not all of them. Read the packaging and instructions that come with your new gasket, and they should tell you where, if at all, you need to place small amounts of sealant.

Q: What Is the Best Gasket Sealant?

A: If you need it, we recommend buying the sealant that comes with or is suggested by the gasket you buy.

Q: When Should I Change My Intake Manifold Gasket?

A: Gaskets are not really things you preventatively change out like oil. You change gaskets when they fail. 

Q: Can I Use Sealant To Repair a Bad Intake Manifold Gasket?

A: We don’t recommend it. If your gasket is bad, do it the right way and replace it. If you take the shortcut, you’ll just end up with more problems down the road.

Video on Intake Manifold Gasket

Car Bibles’ editors understand that not everyone is a text-based learner. For those kinesthetic people out there, we have your back with a video showing you exactly what an intake manifold gasket is. We pulled it from one of our favorite, and most trusted, sources and it’s a great additional resource.

Car Bible’s Favored Related Products

You can buy tools for intake manifold repair at almost every auto parts and home improvement store, as well as online stores like Amazon. You have a sea of options to select from. The ones we like are the Ancel Classic Enhanced Universal OBDII Scanner and Dewalt Mechanics Tools Kit and Socket Set. Check’em out.

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Tony Markovich

Tony MarkovichTony has a thing for pop-up headlights. His first car was a $3,000 1996 Saturn SC2 Coupe, and his current project is a 1970 Opel GT junker. When he's not daydreaming about the Cadillac Sixteen, he's watching the Chicago Bulls go undefeated on TNT. Contact the author here.