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My brand new, or newly rebuilt, turbo is leaking oil. Is the turbo bad?

There are several reasons why new, fully rebuilt, or good used turbos leak oil, having nothing to do with a turbo problem:

  • Excessively high oil pressure/volume: Oil pressure on these turbos should not exceed 60psi. We actually recommend the maximum being 55psi or lower. Any more pressure than this will blow out the seals. All these turbos need at idle is 1/2 of a liter per minute. You can remove the drain line with the engine at idle and let it run into a container of known size to see exactly what the flow/volume is. If excessive oil pressure or volume is found, a restrictor will be needed to remedy this problem.

  • Oil drain too small, bent, kinked, cocked, or entering the engine below oil level: The oil drain is actually the most important factor in keeping a turbocharger from leaking from the oil seals. This is due to the fact that once the oil has gone through the turbo, it is changed into a consistency of whipped cream or foam, and the system relies on gravity to drain all of the oil. Minimum inside diameter of the drain pipe should be 7/16". We recommend inside diameters of at least 1/2", ideal would be 5/8" if possible. The turbo bearing housing should be as perpendicular (or vertical) as possible, and should not "cock" to either side any more than 15°. Once again, we recommend vertical. Obviously, any kinks in the drain line, or sharp bends will cause oil to back up inside the line, not allowing oil to drain. Also, oil entering the engine below oil level will build up the oil inside the turbo, not allowing it to drain.

These are the top two reasons why new, rebuilt, or good used turbos leak oil on custom installations. There are two other less common problems in this area:

  • Restricted or dirty air filter

  • Improperly installed, or non-functioning PCV system

I purchased a rebuild kit. Will my turbo need to be re-balanced after I complete the rebuild?

You will not need to have your turbo re-balanced if the following applies:

  • Neither of the wheels (compressor and/or turbine) have touched or rubbed the housings

  • There are no worn, chipped, or bent fins on either of the wheels

  • You were careful to mark the position of the wheels in relationship to each other prior to disassembly and rebuilding, and then realigned these marks upon reassembly

What will I need to install my turbo on a non-turbocharged vehicle?

Here is a pretty complete list of items you will need to purchase in order to install a turbo on your non-turbocharged vehicle. There could be a few more small things such as nuts, bolts, fuel lines, etc. You will not need an intercooler if you do not plan on running more than 10psi of boost.

  • Turbo Exhaust Manifold or an Adapter (you can purchase one or build your own)

  • Turbo w/ Internal Wastegate (easier to install)

  • External Wastegate (if turbo is not equipped with an internal one)

  • Oil Feed & Drain Lines

  • Water Fittings (if turbo is water cooled)

  • FMU (fuel pressure regulator that increases pressure as the boost goes up) BEGI is the best one made right now

  • 440cc or 550cc injectors

  • Walbro 195/255 LPH Fuel Pump

  • Exhaust Work for turbo connection

  • Misc. Pipes, Clamps, and Connecting Hoses

How do I install/remove a 1-pc carbon seal?

We have installation/removal INSTRUCTIONS for these seals available on our website.

How do I know which style of T3/T4 hybrid turbo I have?

If you have a T3/T4 hybrid turbo, there are four different styles available:

  • Standard shaft model with 270° thrust bearing (this is the most common)

  • Standard shaft model with 360° thrust bearing

  • Big shaft model with 270° thrust bearing

  • Big shaft model with 360° thrust bearing


There are also 3 seal types:

  • One Piece Carbon Seal (1-PC)

  • Four Piece Carbon Seal (4-PC)

  • Dynamic Carbon Seal


The only way to determine which size shaft you have (without taking the turbo apart) is by the size of the compressor end nut. If your turbo has an 11mm (7/16") end nut then it is a big shaft version, and if you have a 10mm (3/8") end nut then it is the standard shaft version. There is no way of determining the thrust bearing type or the seal type you have without disassembling the turbo to see.

Differences between Mitsubishi Turbos Flatback and Superback compressor wheels?

We have a pages showing the differences in these wheel types. Click here to view that page.

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