Although intake manifold gasket is not a common reason for an oil leak, there are cases when this kind of failure can be the cause. As you know, nothing lasts forever and every part of your vehicle has its own life expectancy. While it may take months to years for some parts to wear out or break down, others fail quickly – like an engine’s intake manifold gasket.
So, one day you are driving along and suddenly notice that oil is leaking under the hood of your car. You then take it to a mechanic who tells you that your intake manifold gasket has failed and needs to be replaced ASAP or else your engine will seize up due to lack of lubrication. What do you do next?
The thing is, the intake manifold gasket will always be exposed to super-hot and pressurized engine coolant or water. Compressing the two together under such conditions will result in a lot of heat which could cause cracks over time. Due to its location near the engine’s cylinder head(s), it also makes this part more vulnerable to oil and coolant leaks. In some cases, those cracks can also be caused by faulty cylinder head bolts or a cracked engine block. Either way, once it fails to do its job, you could expect an oil leak if the engine is still running. But what happens when your engine is turned off?
A stopped engine will no longer apply pressure to the intake manifold gasket so it will not have a chance to crack. In such situations, oil leaking from your car could be caused either by faulty gaskets or other related engine problems. So, how do you know whether your intake manifold gasket failed or something else is wrong with your car?
If there are coolant leaks or coolant in the oil tank when you check up your vehicle, that would be a clear sign of a faulty cylinder head gasket. But good thing is, the intake manifold gasket does not usually break down all of a sudden. If there are no symptoms just before it becomes too late, chances are high that this part still has some life left.
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What are the symptoms of a leaking intake manifold gasket?
Symptoms of intake manifold gasket leak include black smoke coming out from the exhaust pipe, oil in the engine coolant tank, and an erratic idle or misfire condition. Note that misfire will not cause an immediate oil leak but a few miles after start-up because the engine is still cold at that time. If your car fails to idle properly on a cold day with a weak spark, that’s the time when you should have your oil pressure checked up immediately.
A small amount of oil leak is always normal and acceptable for older vehicles so don’t panic unless it has some symptoms described above or if the severity of a leak increases over a period of time. If it’s really too late for you to replace your intake manifold gasket, think about getting it rebuilt or repaired instead of buying a new one.
Does oil go through the intake manifold?
In most cars, oil is not used inside the intake manifold – it passes through it only on its way to the engine. While there are some engines [like in older model Porschs] where you can find a small oil passage at the back of your intake manifold, this channel will still only carry a very small volume of oil.
How do you check for an intake manifold leak?
If you are not sure whether it’s the intake manifold gasket that is causing an oil leak in your car, check for these things below:
- Take off the engine cover and look at the top of your engine block. If there is an oily residue near or around this area, that would be a pretty good sign of an intake manifold leak.
- Check your oil tank. If there is a lot of oil in the tank, this also suggests that an intake manifold gasket failed and may be the source of your problem as well.
- Don’t forget to check your engine coolant level as well since it will help you detect coolant leaks or any other possible problems with your radiator.
- To see whether coolant is getting into the oil, open up your oil filter and inspect it there. If you can smell something like antifreeze or if you find some traces of white residue inside, this would be another sign that a coolant leak is present somewhere in your engine.
- If you see oil drippings along the front of your engine, this is most likely an indication of a faulty exhaust manifold gasket. To separate these two problems from each other, turn the car on and listen for the sound of leaking coolant near or under the radiator – in some cases, you won’t even need to get out of your car to check for coolant leaks.
- Watch out for signs of overheating as well – it could be an early indicator of a bigger problem inside your engine. To know if you are approaching the red line, just follow this procedure: Turn the ignition key on but do not start the engine, wait until steam comes out from under your hood, after that, check your temperature gauge. If it is close to or past the “H” mark, you’re already experiencing overheating and chances are high that you have some serious problems with your engine.
- Check for any loose parts in the area of your intake manifold – if any bolts seem loose, this could also be an indication that an intake manifold gasket leak is present.
- If you hear a whistling sound, also called “singing”, this can be another indication of an intake manifold leak. Singing will occur as soon as the engine reaches 2000 RPM – a rapid increase in air intake pressure should produce this effect. A whistle from the intake system while driving means that a vacuum leak is present in either the intake manifold or the air cleaner.
- If your engine runs only on 3 cylinders, this would be yet another sign of an intake manifold gasket problem as it can also cause incomplete burning of fuel inside the cylinder and affect power output. Start by checking for spark plugs – if one of them is wet, it is likely to be the problem. If one of the spark plugs shows abnormal wear or gap, go ahead and replace it – this should solve your cylinder misfiring problem.
- Check fuel injectors for damaged spray pattern – if some of the nozzles seem to deliver an incorrect amount of fuel inside the cylinder, this can also cause complete engine misfiring. A so-called “strangled” or “scorched” spray pattern is the most obvious sign of a broken fuel injector.
- Check the spark plug wires for signs of oil contamination – if you find any, these wires are in bad shape and should be replaced.
- Check your ignition coil and distributor cap for signs of oil contamination as well. If you find any, take a look at the rotor (also called “spark plug adjuster”, which is part of the distributor) as well – if it seems to be wet or oily, you should replace all these components in order to restore an optimal ignition system.
- If you notice a vacuum leak in your intake manifold at idle, it is likely to be leakage from the joints of one or several air tubes – better check them for oil contamination as well and have them replaced if necessary.
- Finally, take a look at your vehicle’s fuel injectors – any indication of an oily residue inside these injectors means that oil is mixing with your fuel.
Can intake manifold leak cause a low oil pressure?
If you have a lot of oil leaking out the intake manifold, this can cause an abnormally low oil pressure. If you suspect that your problem is caused by an intake manifold gasket leak, there are at least 3 ways to confirm it:
- Check for signs of coolant leaks – if any are present, start looking for other symptoms as well.
- Listen for an engine knocking sound while driving – this is the most common symptom of an intake manifold gasket leak.
- Take a look at your oil pressure gauge while driving, look for any drops in oil pressure during idle or after reaching 2000 RPMs.
Can intake manifold leak cause low compression?
If you notice a low compression reading on one of the cylinders, this can be caused by engine misfire – which is more likely to happen if your intake manifold gasket leaks. Low compression readings are also quite difficult to diagnose accurately, but if you suspect that an oily residue inside the cylinders (or excessive crankcase pressure) is causing or worsening this low compression reading – you should start looking for an intake manifold leak as well.
Can intake manifold gaskets be reused?
Can intake manifold gaskets be reused? The answer is NO. Engine gaskets in general are designed to be replaced.
What happens if you reuse a leaking intake manifold gasket?
A leaky intake manifold gasket can cause serious problems to your vehicle:
- An intake manifold oil leak will increase the amount of air and fuel mixture entering the combustion chamber while driving, resulting in a misfire condition. A rough idle at startup is another common symptom of this problem. This will result in loss of power, irregular idling, and poor acceleration. A misfire or rough idle can be quite difficult to diagnose, but if you think that it’s caused by an intake manifold leak – go ahead and replace the leaking gasket.
- Dirty engine compartment oil leaks will get on electrical components like oxygen sensors, spark plugs, and injectors – resulting in these parts shorting out (a short in the oxygen sensors can set a Check Engine Light).
- Excessive oil leaking out of the intake manifold will collect in the engine oil pan, resulting in excessive crankcase pressure – which will eventually cause damage to other engine components located in this area (like exhaust manifolds and piston rings).
In conclusion, the answer to the question of whether an intake manifold gasket can cause an oil leak is YES. An intake manifold leak can also cause an oil pressure problem, and possibly a misfire condition. It might be worth checking for engine oil leaks when you notice problems with your fuel economy or performance.