(Updated on May 20, 2020)
A gasket is basically a seal which goes in between various components of the engine. This seal can be made from metal, paper, rubber, or a combination of them.
This particular gasket goes in between the cylinder head and the intake manifold in order to provide a seal there. As you may know, the intake manifold is responsible for delivering the mixture of air and fuel to the cylinders.
If there is a problem with the intake manifold gasket and it is unable to properly seal these two components, then you could have major problems.
Bad Intake Manifold Gasket Symptoms
1) Coolant Leaking
Some vehicles have water jackets in the intake manifold for cooling the intake charge. On these setups, the intake manifold gasket functions a bit like a head gasket, in that its purpose is to seal against both air and coolant leaks.
Naturally, if this seal were to be worn out or damaged, then coolant fluid will be able to seep through the seal and leak out. The leak could either be external (into the engine bay) or internal (into the intake manifold, then the combustion chamber). You may know when this is happening because the smell of coolant will be in the cabin and it is a very distinct smell.
If it gets really bad, then you might even see steam and puddles of coolant from under the vehicle. The vehicle could overheat if it loses too much coolant, and will blow white smoke if the coolant is burned in the combustion chamber.
2) Engine Stalling
When the engine stops turning or is turning too slowly, then stalling will occur. This can happen when a faulty intake manifold gasket causes a vacuum leak, which messes up the ratio of air to fuel.
Then you could be driving and all of a sudden experience a stalled engine. Of course, there could be many other reasons for a stalling engine, but a bad intake manifold gasket is surely one of them. Go see a mechanic to have them verify if it is this gasket or not.
A mechanic will be able to perform a smoke test to rule out vacuum leaks. A smoke test injects smoke into the intake system. If there is a leak in the system, smoke will come out from an area it’s not supposed to.
3) Overheated Engine
An overheated engine is a continuation of the coolant leaking problem. If your bad intake manifold gasket has caused an internal coolant leak, then the coolant is going to get into the intake manifold. Once this happens, your engine will eventually overheat.
You may not even see any visible leaks coming from your vehicle on the outside. But you will know if your engine is overheating because it will show on your dashboard.
It is best to get this issue addressed as soon as possible. An overheating engine is likely to cause other more severe damage if left unchecked.
If your engine is overheating, you will want to rule out other parts of the cooling system to make sure you are replacing the right part. A leak down test will tell you if your head gasket has failed or the head has cracked instead.
You could also test the thermostat to ensure it is working properly. A thermostat that is stuck closed will also cause overheating issues.
4) Bad Fuel Economy
Since a faulty intake manifold gasket causes a disruption in the air to fuel ratio, then your engine is going to consume more fuel than normal.
This means you will be spending more money on gas for doing the same amount of driving that you normally do. As a result, your fuel economy will decrease greatly.
5) Loss of Acceleration
Aside from an engine stalling, you may notice a simple loss of acceleration after you step on the gas pedal. You may get a little bit of power at first, but then the acceleration will stop and start again as you keep your foot on the pedal.
You obviously shouldn’t continue to drive your vehicle when it is in this condition since it’s dangerous to do so. If you are experiencing two or more of the other symptoms, then you definitely need to have your intake manifold gasket replaced promptly.
Intake Manifold Gasket Replacement Cost
The replacement cost of an intake manifold gasket is anywhere from $190 to $540. The cost of the labor will be anywhere from $170 to $420. The gasket itself is very inexpensive and will cost somewhere in the neighborhood of $20 to $120.
You may have multiple intake manifold gaskets if you have a V6, V8, boxer (Subaru and Porsche), or other engine layout with multiple cylinder banks. All intake manifold gaskets should generally be replaced at the same time.
On top of these costs, you will need to worry about the additional fees and taxes too. Overall, though, this is not an expensive replacement job and it should be affordable for most drivers to get done.
Can You Drive With a Bad Intake Manifold Gasket?
While it is indeed often possible to drive with a bad intake manifold gasket, you should not drive too far. Issues like this don’t go away on their own, and they also don’t tend to get better with time.
Leaking additional unmetered air into the combustion chamber has the potential to make the car run lean, which means the engine is likely to run hotter. Knock or predetonation is also more likely. Too much knock under load can actually destroy a perfectly good engine.
An overheating engine is likely to cause additional damage to the engine, including a warped or cracked head or a cracked block. This damage would cost far more to repair than a simple intake manifold gasket replacement normally would.