One morning, when getting ready to go to work, you decide to remove the plastic intercooler cover and discover a patch of oil on the corner of the intercooler. This discovery can be quite disconcerting, especially if you are new to such kinds of problems. The intercooler is a critical component in your turbocharged engine.
Usually, the supercharger or the turbocharger compresses the air, and the process causes overheating. Heated air reduces the density of oxygen, and that is where the intercooler comes in.
It is up to the intercooler to lower the temperature and allow denser and more oxygen-rich air needed for efficient combustion and engine power.
Your turbocharged vehicle has an Intake Air Temperature (IAT) sensor to control the ignition depending on the temperature. The lower the temperature, the more the ignition advance the system can allow during boost, which translates to more power.
In the absence of an effective intercooler, the IAT goes up and causes the ECU to retard the ignition instead of boosting it.
The intercooler does not need any oil to function. It comes from the turbocharger. Typically, the turbocharger can reach speeds of up to 280,000 rpm, and lubrication is critical.
The turbocharger gets its lubrication from the engine lubrication system, and over time, some leakage from the seal can find its way to the bottom of the intercooler.
A small amount of oil is normal and should not drive your anxiety levels off the hook. But if the leak is a lot, have it checked out by a certified mechanic.
What the Oil in the Intercooler
Means Some oil sweating down from the intercooler, bleeding boost, and lackluster performance means that all is not well. Sometimes, you may also notice that the turbo whistle is not as audible as it used to be.
Oil from the charge tube should be cleaned and checked for further leaks. If there is oil on this part, then it can mean turbo failure. It is not an intake issue.
Possible Solutions to Oil in the Intercooler
Cleaning, Testing, and Installation of a Stronger Bash Plate
Reputable mechanics should perform an external and internally clean, conduct a pressure test and fix any leak. Some vehicle owners opt for a more robust front bash plate for a better protection degree and prevent the problem from recurring.
Installing a Catch Can
One solution that can prove quite effective is installing an oil separator or catch can, a relatively straightforward process. There are several aftermarket offers and options.
For example, there is an option that reroutes most of the EcoBoost vacuum lines to the catch to solve the condensation buildup and oil leakage problem.
However, this solution is not without drawbacks. Installing a catch can means that you will periodically need to drain it. A practical catch can should recirculate the oil vapor without affecting the emissions components.
Most of the new cars these days are either supercharged or turbocharged. As a result, there is an uptick in oiling and condensation problems.
The positive crankcase pressure can exceed what the OEM PCV can handle when there are performance modifications. The number of piston rings blow-by will also increase.
If you notice oily gunk leaking out when you pull the inlet hose from the intercooler, it means that the PCV is restricted or clogged.
A clogged PCV system will leave carbon deposits as oil is sucked in the cylinders and likely cause a misfire. In some of the newer engines, the PCV system is not just a check valve. It is more than that, and this presents a few challenges.
A PCV built into the valve cover and controlled with the ECU is now more common in newer models such as the Volkswagen/Audi TFSI engines. An oil separator is also incorporated together with the PCV system into the cover in turbocharged applications.
When a misfire occurs in engines like the Audi TFSI, the culprit is often the diaphragm seal failure on the oil separator. An aftermarket replacement diaphragm or the replacement of the whole PCV unit can solve the issue.
In most cases, the OEM PCV system should comfortably handle most of the crankcase ventilation. That is unless you neglect regular maintenance.
Boosted applications that go beyond stock require more airflow to allow the escape of crankcase vapors specifically. You can solve this issue by installing another line or increasing the hoses I.D. to reduce pressure.
Oil Leak After A Turbocharger Replacement
In the majority of the cases, turbocharger damage can also cause intercooler failure. Replacing the turbocharger comes with a host of risks if the installation is not done correctly.
Oil and other residues blown from the turbo can clog the intercooler and cause leaking and other problems. Sometimes, the new system pressure leads to the intercooler leakage and eventual deformation of the plastic tank.
There is a high risk of blockage and increased system pressure after installing the new turbocharger if the residue is left in the system. This means that the intercooler will have to handle more pressure than it was designed for, and this will cause it to fail.
The same problem also becomes apparent when you manually increase the output of the turbo. Typically, the increased pressure from this modification is more than what the intercooler can manage, and the risk of the tank blowing goes up.
In certain cases, an inexperienced technician installs a powerful turbo without first inspecting the intercooler. In that case, the system will operate at abnormal pressures and blow oil and other debris accumulated in the intercooler into the combustion chamber. Left unchecked, this pressure and the residue blown into the combustion chamber poses a greater risk of damage to the engine.
But what can be done to prevent engine damage?
Ideally, the intercooler should always be replaced together with the turbocharger. This ensures that it is free from any debris and oil.
The technician should thoroughly inspect all the system components for any metal or oil blockages when installing the new turbo. More importantly, the reason for the turbo damage should be investigated thoroughly before installing the new one. Otherwise, the problem may recur and even cause engine damage, which is even worse
Robert Anderson is a world class motorhead who rebuilt his first carb at age 10, his first engine at age 15, and completed his first full hotrod build when he was just 18! Previously, he has ran a part warehouse, delivered pizzas, and managed the service department for a $20 million/year revenue dealership. Robert knows cars like few others and he is passionate about sharing his knowledge.