Don’t Panic, it's probably not your turbocharger at all. There are many reasons your turbocharger could be leaking oil without it having to do anything with your turbocharger directly. With the introduction of forced induction for the 2016+ Honda Civic this may be your first turbocharged Honda even if it's not your first Honda car. Let’s get familiar with oil leaks on turbocharged engines so you know how to handle them. 

This blog is not a “how do turbochargers work” blog. For that, you can click here and then come back and resume this blog. In this write up we are going to give you what to check for on your late model Civic in the rare case it's leaking some engine oil from the area in the front of the oil pan. Let's jump right into it. 

The oiling system for your turbocharger is rather simple. Oil goes in, spins around in the turbo and then the oil comes out. So let's follow that path from end to end. We start at the engine block with pressurized oil coming out. There is a little hole in the front of the block that this high-pressure oil exits to enter your turbo oil feed line. It is sealed with a simple O-ring. If you are leaking oil in this area then it’s probably a missing or damaged O-ring. This O-ring is maintenance-free and not something that you should ever have to worry about but if you remove this hard line for any reason (like W1 turbo swap) then it is possible it got pinched, dirty, or even wasn’t put back on.

Following the oil path next, you’ve got the oil feed line itself. If you are still on an OEM turbocharger then check out the two braised spots at the bottom and top of the oil line. These are known to weaken over time and can crack which will cause oil to leak out. If you are running a W1, W2, or CTR Kuro turbocharger then you will have a few more spots to check. As opposed to the OEM one-piece line our turbos come with a 3 piece setup. We outline in our install instructions (found at the bottom of product listings) the importance of making sure these connections are tight. If these fittings are loose an oil leak can happen.

The last part of the high-pressure feed side is the banjo bolt attaching the feed line to the turbo CHRA. The line is secured with a banjo bolt and a pair of crush washers. One crush washer above and below the line itself. There are a few super important things to note here. First, make sure the crush washers are new and not deformed or broken. Second, make sure you have both crush washers installed in the right place. Third, make sure the banjo bolt is torqued to specifications. It’s worth repeating - that’s not tight by hand but torqued to spec with a torque wrench. Crush washers are designed to deform. If you over torque them then you flatten them out and create a big leak. A mistake in any of these 3 steps will result in oil shooting out everywhere.

Next, we follow the oil into the turbocharger. What could cause an oil leak from the turbo itself? Well, a few things actually. Overfilling your engine with oil, idling for extended periods of time, too much positive crankcase pressure from a faulty PCV valve, and worn turbocharger piston rings can do it. If you are certain your oil leak is coming from the turbo itself then you should try and determine if the oil leak is coming from the compressor wheel side, the turbine wheel side, or the CHRA itself. If coming from one of the wheels it can be from one of the first three things listed above. If you are certain that the leak is coming out of the center section itself then you will want to get your turbocharger looked at by a professional. 

If you have inspected the oil path thus far and still didn’t find your leak then it’s time to check the oil return. The oil leaving the turbo works off of gravity and is returned down a tube into your oil pan via a big port on the block.

You will want to check the areas marked with red arrows in the image below. Starting from the top make sure both bolts to the CHRA are torqued to spec and the gasket in between the flanges is in good shape. Also, make sure there is a gasket there lol. Next, make sure both hose clamps are nice and secure. Lastly, make sure the rubber tube is securely over the port on the oil pan. Yes, we have seen cases where that was left off and made a big puddle. It’s also possible for the rubber return line to crack or get cut.

As a general rule of thumb, if there is oil squirting out at high velocity then the leak is likely on the feed line/pressure side. If you have more of a slow dribble or puddle then your leak is at the CHRA or the return line. 

I hope this blog helps you feel more confident to work on and diagnose your 1.5L turbocharged Civic or Accord or 2.0L turbocharged Type R or Accord. Let us know what you think below.

Happy tuning
-Vincent
-Co-Founder