DIY: Boost Leak Tester


Jun 04

Here’s one idea how to do boost leak testing:
Hook up one end of you boost leak tester to the intercooler piping and the other end to the air compressor valve or pump. Pressurize the intercooler piping and use 5/8″ hose to listen in & pinpoint any air leaks. You can do boost leak testing on individual intercooler pipe pieces / blow-off-valves, etc. as well if you suspect they are not holding up to the desired pressure.

*** NOTE: Use safety goggles – pressurized piping + things lying around it become potential projectiles.

This is what I typically do:

  1. With engine off, I usually remove coupler that connects intercooler piping to turbo, install my boost leak tester there.
  2. Pressurize the whole system, prop open the gas pedal with a piece of wood or brick to ensure I get full pressure flow for testing any manifold leaks as well.
  3. Obviously there will be some leakage depending on cam/valve positions where the engine stopped, so pressure may drop over time. What we are doing is
    listening to external air leaks around couplers, throttle body, manifold, piping, etc.
  4. To aid in listening for the air leaks, grab a 5/8″ hose .. While your buddy or you keep pressurizing the piping to specific psi with hand valve, walk around & probe with the hose for leaks. If you hear a leak through the hose, look where the other end is pointing then turn it to figure out the exact spot of the leak.
    (Note: quiet pressurized air chamber with air compressor off makes sense – loud compressor working in the background does not since you won’t hear any air leaks).
  5. Once you figured out the issue, solve the leak – if it’s piping, reweld it, if it’s hose coupler, tighten it up, etc. then retest until the pressure stops dropping fast.

That was my brief idea on boost leak testing. Now, let’s make the tester. Here’s what you’ll need:

  • A gauge to measure pressure that you’ve built up in the intercooler piping (or you can use the one inside your car if you have it mounted already).
  • Air compressor that you can turn on / off or buddy with a footpump to pressurize the piping up to specific pressure you want to test for. If it is an air compressor, make sure that you have quick on/off switch handy to ensure you do not over pressurize the piping beyond what you are testing for OR you will definitely find a leak or make a new one fast. I test my piping to 22 psi since at most I am peaking 17 psi. If I upgrade bunch of things and my requirements change, I’ll have to raise the pressure level for testing as well.

After making few dual gauge pods a while ago, I ended up with 2 1/16″ wooden cylinders that came out after the cutting was done. My intercooler piping on the hot side is 2″ so putting the 2″ intercooler coupler fits well over the wooden cylinder – just needed to clean up the edges a bit and wholla.

Notice the X in the middle of the wooden cylinder. It is the X used to mark the gauge center – I didn’t even have to drill the center since the cutout saw drill did it for me when I was making the gauge. I hammered in a 2 way barbed fitting so that I can attach vacuum hose for pressurizing the tester. I did clean the center a bit to make sure I won’t dump some wooden pieces in the piping, but it was a win-win situation: make gauge pod, reuse pieces to make a boost leak tester all in one shot.