Tech Tip #12: Turbo Oil Line Etiquette

The majority of turbo failures we have seen over the years were caused by oiling issues stemming from improperly configured oil lines. In this week's tech tip Jay tells you what you need to know about the oil lines in your turbo setup.

The name if the game here is getting enough oil into the turbo to keep the moving parts lubricated, and getting it out of the turbo fast enough that it does not build up pressure inside the center cartridge.

The first thing you should know is that the oil drain on a turbocharger relies on gravity to direct the oil out of the turbo. The oil must be able to "fall freely" out of the bottom of the turbo on it's own. It is for this reason that the oil drain on the bottom of the turbo should point straight down at the ground when the turbo is mounted. The further the oil drain points away from down, the worse the oil will flow out of the turbo. When oil has a hard time getting out of the turbo fast enough, pressure builds in the center cartridge and thats when oil leaks past the shaft into the parts of the compressor housing or exhaust housing where it will cause smoking and oil consumption.

The next thing to remember about gravity is that the oil drain of the turbocharger should be higher off the ground than the fitting it connects to on the oil pan. You want the oil to fall vertically out of the turbo in a downward direction through the oil drain line and into the oil pan unobstructed. We sometimes see low mounted turbochargers for forward facing setups or setups that tuck twin turbos next to the transmission in a v8 rwd car that have horizontal oil drain lines...but as the turbo drain gets lower and lower, the oil will have a harder time "falling" into the oil pan. If the turbos get low enough that gravity cannot drive the oil into the oil pan anymore, a scavenge pump may be required to pull the oil out of the turbocharger and push it into the oil pan.

The next thing you want to look at is the hose size and fitting style for your oil drain line. The oil drain hose and fittings should be big inside. The last thing you want is too small of an oil drain line, or a fitting that gets very narrow inside ristricting the free flow of the oil out of the turbocharger and into the oil pan.

Remembering these things can help you avoid common oiling issues that we see people often make.