Dan Ferrell writes about DIY car maintenance and repair. He has certifications in Automation and Control Technology and Technical Writing.
Intake Manifold Gasket Replacement
Intake manifold gasket replacement can be a relatively simple or quite complex operation, depending on the vehicle model you are working on and your own experience.
In most cases, replacing the gasket is a viable project for the home mechanic, and relatively inexpensive. Depending on the engine model, an intake manifold gasket can cost anywhere from a couple of dollars to a hundred dollars or more.
Besides, you can purchase a single intake manifold gasket or a whole set if you are rebuilding your engine.
If you want to change the gasket yourself, or want to explore this possibility as an option, here are some recommendations you can use that will help you carry out the project successfully.
Before you begin, make sure you have the vehicle repair manual for your specific model. If you don't have one yet, you can buy a relatively inexpensive copy through Amazon.
Haynes manuals include:
- Step-by-step procedures
- Electrical diagrams
- Description of the different systems
- Component locations
- Bolt torque specifications
- Maintenance schedule
The manual walks you through the procedures to replace the intake manifold gasket in your particular vehicle model, and will help you in future maintenance and repair projects. So a small investment now can save you a lot of money later.
In This Article
- Is there a Technical Service Bulletin (TSB) for your Vehicle?
- Why Does an Intake Gasket Fail?
- Is Your Intake Manifold Gasket Leaking?
- Intake Manifold Gasket Replacement
There is also a video: "Checking Vacuum Leaks With Propane Gas"
1. Is There a Technical Service Bulletin (TSB) For Your Vehicle?
The first thing you need to do is check whether there's a TSB for your particular car model.
It is not unusual for one or several models to come out of the factory with gasket or some other components failures due to bad engine design or part.
Some General Motors engines built between 1996 and 2002, for example, have experienced unusual intake manifold gasket failures. The problem was the material used in the gasket. The corrosive acid in the antifreeze eats away the gasket.
GM had to issue a TSB for these models to have the intake gasket replaced.
If there is a bulletin for your model, the manufacturer will recommend a new type of gasket that you will need to use to resolve the issue. You can check if there is a bulletin for your model using the NHTSA (National Highway Traffic Safety Administration) database.
2. Why Does an Intake Gasket Fail?
There are two main causes of intake gasket failure:
- The difference in the rate of contraction and expansion of the intake manifold relative to the engine head which ultimately destroys the gasket.
- Chemicals in the antifreeze can also accelerate gasket wear, causing antifreeze, oil or vacuum to leak.
3. Is Your Intake Manifold Gasket Leaking?
The intake manifold gasket is designed to prevent oil, antifreeze, and air (vacuum) leaks. Likewise, the cylinder head gasket creates a seal to isolate the flow of antifreeze, engine oil, and combustion gasses between the head and the engine block. This can make it difficult to determine if the intake or cylinder gasket has failed. Or whether you are facing a different kind of problem.
Having said that, intake manifold gasket failure is the most common cause of engine coolant leaks.
These three tests can help you determine if the manifold gasket is the cause of an engine failure:
- Check Coolant Level: An intake manifold gasket leak can cause the coolant level to drop gradually. However, the antifreeze can evaporate before finding an exit, leaving no traces behind.
- Visually inspect the area: Check around the gasket area between the engine head and the intake manifold. Depending on the model of the car, you may have to use a headlamp, a telescoping mirror, and perform an under-engine inspection as well to thoroughly check all areas.
- Check for Air (Vacuum) Leaks: An intake manifold gasket leaking vacuum will cause a lean mixture in the exhaust and trigger a diagnostic trouble code (DTC) (P0171, P0172, P0174). These types of leaks are easier to detect with the use of propane gas which can cause an engine shift when the gas is administered near the source of the gasket leak. The following video shows you how to perform this test.
Checking Vacuum Leaks With Propane Gas
If you are dealing with an intake manifold leak, you need to verify that the gasket surface of both the manifold and the engine head are completely flat and in good condition. You do this check after removing the intake manifold.
In this case, send the intake manifold to a machine shop for inspection. If the manifold needs to be refaced, the cylinder head may need to be rectified as well.
Other signs that you are dealing with a failed intake gasket include:
- Engine overheating
- Poor acceleration
However, these symptoms are not exclusive to failed intake manifold gaskets. In the Resources section at the end of this post, you can find help for cylinder head gasket related problems and intake manifold leak diagnostics.
4. Intake Manifold Gasket Replacement
Each engine model is different, and there is a wide variety of materials and designs used in the manufacture of gaskets that require different strategies for correct replacement.
Even more, on some car models access to the manifold is easy, on others you will need to remove several components before you can reach the manifold. This may represent a challenge sometimes.
4.1 The Repair Manual is your Best Guide
For this reason, it is necessary to follow the steps outlined in the repair manual for your specific model to change the intake manifold gasket. Besides guiding you step by step, telling you what parts you should remove and how to remove them, the manual will offer some suggestions to do a better job:
- How to disable the fuel system, if you need to remove fuel lines.
- The location of each manifold screw.
- In what order should the manifold bolts need to be loosened (on some models).
- Whether you should use a sealant for the gasket.
- The bolts' torque specifications for intake manifold installation.
4.2 Basic Steps
Still, replacing the intake manifold gasket requires a few basic steps:
Wait until the engine is cool enough to drain the coolant into a clean container. You don't have to drain it completely, just until the coolant level is below the intake manifold, unless your manual says otherwise.
Store antifreeze in a safe place, so you can reuse it or recycle it later.
- Disconnect the battery and, if necessary, follow the steps in your manual to remove any covers located on the engine, and then remove the air cleaner assembly.
Tag and disconnect intake manifold vacuum hoses, remove the throttle body, fuel rails, and all other components necessary to reach the intake manifold.
In some models, it is necessary to deactivate the injection system, and remove the harness or wiring along with the fuel injectors; Also, you will have to disconnect the exhaust gas recirculation system (EGR) from the manifold.
Keep removed parts organized in a safe place along with related screws, nuts, wires, and accessories, in the order in which you are removing them. This will make reassembling much easier.
- Depending on your particular car model, and to ensure that the intake manifold does not distort, loosen the bolts in the reverse order in which they will need to be tightened. Start with the bolts located towards the outside of the manifold, ending with the bolts in the center. Consult your repair manual.
- Depending on your particular model, especially on four or six inline cylinder engines, it may be necessary to raise the front of the vehicle and secure it with jack stands to gain access to the lower manifold bolts.
Remove the upper and lower manifold, depending on your model, and perform a visual inspection of each.
If the manifold appears stuck to the head of the engine, use a rubber mallet to break it loose, using gentle taps to prevent damage. You may use a screwdriver if you know you won't affect the manifold's or cylinder head's gasket surface.
Once the manifold is removed, cover the intake ports on the cylinder head with paper towels to prevent dirt or other objects from falling into the head, especially when you are cleaning the gasket surface.
Thoroughly clean the gasket surface on the intake manifold and cylinder head.
You can use brake cleaner spray or some other special chemical found in auto parts stores. Also, when working on hard residue, use a plastic spatula. Avoid using metal spatulas and abrasive brushes. This may wear out the surface and cause leaks in the future.
- Buy the correct gasket for your specific engine model. If necessary, use the Vehicle Identification Number (VIN) to ensure you are purchasing the correct gasket. And handle the new gasket carefully to avoid damage.
Install the intake manifold using the new gaskets.
If your repair manual says to use a high temperature RTV sealant or some other adhesive with the gasket, don't use too much. The sealant is not as strong as a gasket and can create weak spots. The sealant could also block the capacity of the gasket to absorb. The gasket must absorb oil to expand and create a better seal for the intake manifold.
- Verify that the surface on the intake manifold and cylinder head are completely clean. Oil residue, dirt, rust, traces of the old gasket, and dried sealant will prevent the new gasket from sealing completely.
- Verify that the threads for the intake manifold bolts are completely clean and in good condition. Some engines require the use of sealant for the threads of the intake manifold bolts. Check your repair manual.
- Place the new gasket in the correct position on the surface of the engine head or manifold. Compare that the holes for the bolts, the oil, and the antifreeze in the gasket and the surface of the engine head and the manifold match. Some gaskets are marked with guides such as "top" or "front". If you install the gasket incorrectly, you could cause the engine to overheat, lose oil pressure, and ruin the engine.
Install the intake manifold bolts by hand to ensure they go in without any difficulty. Next, use a torque wrench to tighten the manifold bolts to the specification listed in your repair manual, following the indicated sequence.
Make sure you are using the correct torque values. In some manuals, bolt torque values are listed in pound-inch (lb.in), not pound-foot (lb.ft).
Likely, you'll begin tightening the bolts starting from the center, ending with the bolts on the outside of the manifold. In some cases, the screws are tightened in three steps. Check your repair manual.
Reinstall the rest of the engine components; install the vacuum hoses in their correct places, and refill the cooling system, if necessary, with new antifreeze.
Consult your owner's manual to find the right antifreeze for your model and how to bleed the system to prevent overheating. You'll find some help in the Resources section at the end.
- If the engine oil has become contaminated with antifreeze due to a manifold gasket failure, drain and refill the engine with the oil listed in the manual as well.
- With everything in place, start the engine. Check for leaks and verify that the engine runs properly.
- On some modern engines, it is necessary to use a scanner to reset the engine idle. Check your repair manual.
- If everything seems OK, do a test drive and check for any leaks.
- Diagnosing an Intake Manifold Leak
Intake manifold leak diagnosis can be tricky. A leak may occur for more than one reason, including a disconnected vacuum hose. Here are a few simple techniques and steps to find the problem.
- Symptoms of a Blown Head Gasket
Symptoms of a blown head gasket are varied and usually get confused with faults in other systems, unless you know what to look for and what diagnostic tools to use.
- Engine Head Gasket Repair
An engine head gasket repair could be a feasible project to do at home, if you know about the different necessary resources.
- Engine Hesitates During Acceleration But Gives No Trouble Codes
When engine hesitation occurs with no trouble codes, you could feel at a loss, but this post will help you find the problem.
- How to Change the Coolant Without Causing the Engine to Overheat
How to change the coolant in your own garage, and purge the system to avoid making the engine overheat.
- Diagnosing Trouble Codes P0171 and P0174
Don't let trouble code P0171 or P0174 leave you without your ride and, worst of all, with an expensive repair bill later on.
- P0300 Random Misfire Diagnosis
P0300 random misfires can be hard to diagnose, leave you stranded and with an expensive repair bill, but this guide can help you.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
© 2022 Dan Ferrell