Causes of Intake Manifold Leaks
Damaged Seals
The gaskets that seal the intake manifold can wear, crack, or become damaged over time. This can cause air and coolant leaks, which can lead to a variety of problems like those mentioned above. Car manufacturers don’t typically have a replacement schedule for intake manifold gaskets, so they’re usually only replaced when they leak.
Broken Intake Manifold
Cracks in the intake manifold are also a common cause of leaks. Cracks or holes in the intake manifold can allow excess air into the combustion chamber, which can cause air-fuel ratio-related problems like misfires. Continuing to drive with a cracked intake manifold can lead to more serious problems. Therefore, it is important to have your intake manifold repaired as soon as you notice the symptoms.
Loose components
Intake manifold leaks can occur if components become loose or separate. If the bolts that secure the intake manifold become loose or the vacuum hose becomes dislodged or damaged, air can enter the system. Inspect it regularly and tighten any loose parts. Replace any damaged hoses to prevent leaks and keep your engine functioning properly.
Troubleshooting an intake manifold leak
If your engine has an aluminum cylinder head, you can expect corrosion near the cooling ports. There is plastic under the seal bead on the intake manifold that may also be corroded.
If you see this, it means the seal is not holding and is prone to leaking. So in this case, the seal is not the cause of the leak.
Checking an intake manifold for leaks should not be done by an inexperienced mechanic and should in most cases be left to a professional. However, here are the general steps:
Coolant Leak Inspection
If the coolant is leaking from the outside of the seal, you can see it with your own eyes. However, if you have an internal leak that is causing coolant to get into the oil or combustion chamber, you won’t be able to detect it that easily.
You should check the system completely. First, check the oil for foaming or any other type of contaminant. You should also get the code so you know exactly what you’re dealing with. If the code references the oxygen sensor or efficiency sensor, it means coolant has entered the combustion chamber. Coolant contains phosphates, among other chemicals, which can lead to damage to the catalytic converter and oxygen sensors.
If you have a V8 or V6 engine, you can use the code to find which bank is leaking. A large leak in the port can cause the misfire code. If this problem occurs over an extended period of time, remove all spark plugs in the vehicle. Check to see if there is a chalky white deposit on the electrode. This is the mark that the coolant leaves on the electrode.
Air Leak Test
Even the smallest vacuum leak in the intake manifold can cause problems with fuel conditioning. Finding a leak using only your eyes and ears is very time consuming.
Every time air leaves the intake manifold, it is sucked in instead of pushed out. Whatever is in the intake air will affect the fuel-air mixture, which in turn affects the exhaust and engine systems.
If you have a fogger, you can diagnose multiple leaks in less time. This machine does this by pressurizing the intake manifold while pumping steam and smoke into the system. So, if there is indeed a leak, the smoke will be extracted.
Find the vacuum port and connect the smoke machine, just like you would connect a brake booster to a supply line. If you block the throttle body, make sure you use the correct size plug. The PCV system should also be blocked.
If you have smoke coming from the PCV system or oil filter and the engine is not misfiring, it could mean you have a crack or leak under the intake manifold. It could also mean that the valve seals or guides are too worn.
Is it safe to drive with a leak in the intake manifold? While short distance driving is possible, long distance driving is not recommended. A leak in the intake manifold can cause performance issues such as misfires and reduced power and fuel economy. But more importantly, it can disrupt the cooling system, causing overheating and engine damage.
If you notice a coolant leak or damaged seals, we recommend having a professional mechanic inspect and repair the problem as soon as possible.