5 Signs of a Bad Intake Manifold Gasket (& Replacement Cost)

The distribution gasket ensures that no air leaks from the manifold. Here's how to tell if your manifold gasket is bad and how much it costs to replace it

intake manifold gasket

Your intake manifold does a ton of work and is a critical part of your engine. While the intake manifold itself is typically pretty sturdy, the gasket seals between the manifold and the cylinder head are known for failing.

But how do you know that you have an intake manifold gasket leak, and what does it mean if you have one? More importantly, how much is it going to cost to fix?

We’ll break down everything you need to know to fix this pesky problem here. Let’s take a quick look at the signs to look for first:

The most common symptom of a bad intake manifold gasket is a misfiring engine and white smoke coming from the exhaust. You can also notice external coolant leaks if there is coolant going through the manifold. Mostly, it will also show a check engine light on your dashboard too.

Here is a more detailed list of the symptoms of an intake manifold gasket leak.

Intake Manifold Gasket Leak Symptoms

1. Poor Engine Performance & misfires

car misfires

A leaking intake manifold lets air out and coolant in. Both of these things can negatively affect performance. It’s not very likely that you won’t be able to get your vehicle started or that your engine will shut off while running, but you might notice a drop in acceleration and fuel economy.

The biggest concern is that if the coolant mixes with the oil, you’re not only losing the performance of the coolant, but the oil won’t be able to function correctly either. This can lead to excessive wear on a lot of components and cause expensive damages.

You may also find misfire trouble codes in the engine control unit if you check the trouble codes with a scanner.

If the intake leak is very bad, it can fill up the cylinder with coolant, which will make your engine hydrolock, which will make it impossible to turn over. This is very serious and can damage your car seriously. Luckily it is not very common because most car engines are designed, so the coolant will pour down into the intake manifold instead.

2. Excessive White Smoke from Exhaust

oil smoke car e1609805071325

When you’re looking at your intake manifold, you can’t exactly see what’s going on inside unless you tear apart your engine, and at that point, you should replace the intake manifold gaskets whether they were leaking or not.

That’s why it’s essential to know how to troubleshoot this problem without taking anything apart. The easiest way is to start your vehicle and take a look at the exhaust. If there is an excessive amount of white smoke coming out of the exhaust, it’s because your engine is burning coolant. 

The only way coolant gets into the combustion chamber is if there is either a leaking head gasket or a leaking intake manifold gasket – either way, you have a problem. When determining if the amount of white smoke is excessive, keep in mind that you’ll have more smoke during colder weather than you will during warmer weather, and this is completely normal.

3. Coolant In the Oil Pan

engine oil dipstick

One of the most common problems of a leaking intake manifold is that you’ll find coolant in the oil pan. Unfortunately, this is also one of the more serious issues. Not only are you losing out on the cooling properties of the coolant, but you’re also losing out on the lubricating properties of the oil.

When you combine these two problems, you can quickly end up with a vehicle requiring extensive repairs to get back on the road. If you find coolant in the oil pan, make sure you get your vehicle to the repair shop right away. You can easily recognize the coolant in the oil pan because the oil will look milky when you check the dipstick’s oil level.

4. Visible Coolant Leak

coolant leaking e1609789888621

If you have a leaking intake manifold gasket, there are a few ways the coolant can go. First, it can go into the combustion chamber, which is how you get excessive smoke, or it can merge with the oil, which is how you can get coolant in the oil reservoir. But it can also run off the side of the exterior of the intake manifold.

If this is the case, you might have excessive smoke coming off the top of your engine if the coolant burns off before it reaches the ground. Or you might have a visible coolant leak on the ground underneath your vehicle. Either way, if you trace the leak back to the intake manifold, you’ve found your problem.

5. Overheating Engine

engine overheating

The three most prominent symptoms of a leaking intake manifold involve leaking coolant. Since it’s the coolant’s job to keep your engine from overheating, it’s not surprising that if it’s not working correctly, you can get an engine that overheats.

This won’t happen immediately, and it usually occurs once the system runs low on coolant. But if you have an overheating engine and can’t figure out where the coolant is going, there’s a good chance that it might be coming from a leak in the intake manifold.

Intake Manifold Gasket Function

intake manifold gasket

The intake manifolds function is to direct the correct fluids, gasses, and engine necessities to the correct location throughout the engine. The intake manifold gasket assists with this by eliminating any potential escape routes for these fluids or gasses.

The intake manifold gasket forms seals around each of the passages in the intake manifold, keeping everything where it’s supposed to be. It might not sound that complicated, and it’s not, but that doesn’t make it any less important.

Intake Manifold Gasket Location

intake manifold gasket

Your vehicle’s intake manifold gasket is located near your engine’s head between the intake manifold and the cylinder head. On V-shaped engines, it usually sits between both headers. For inline engines, it usually sits off to one of the sides.

Reaching your intake manifold usually isn’t too complicated, but there can be many electrical components sitting on top. Not only can this make it hard to access the intake manifold, but it can make it harder to see too.

Intake Manifold Gasket Replacement Cost

The average intake manifold gasket replacement cost is between $80 and $400, depending on the car model and labor costs. An intake manifold gasket costs $30 to $100 and labor costs $50 to $300.

The intake manifold gasket itself is often quite cheap, but most of the replacement cost comes from labor costs. This is because you have to remove the whole intake manifold to reach the gasket.

Sometimes the intake manifold cracks, causing it to leak near the gasket, and in this case, you can expect a cost of $200 to $800 for a new intake manifold.

Written by:

Magnus is the owner and main author of MechanicBase. He has been working as a mechanic for over 10 years, and the majority of them specialized in advanced diagnostics and troubleshooting. He has also been a motorsport (drifting) driver for over 5 years.