Where can I find the correct size fernco couplers to build a boost leak tester? I tried Home Depot, Lowe's, and Ace with no luck on the correct size. The outside diameter on the turbo inlet is 4". I can only find fernco sizes that are 4.5 to 3.5", nothing close to 4".

 

I got mine at Lowes. Try a different one maybe?

 

Sorry I am a little new to my cummins, what is a leak detector made of and how does it operate?

 

NK do a title search for "leak tester". Basically its made of a rubber fernco reducer sized 4" to 3", a 3" PVC cap, and a valve stem (like whats used for tires), and the appropriate 4" and 3" hose clamps. You put the PVC cap inside the 3" end and drill a hole to fit the valve stem in the center of the cap.

Basically if you think you have a boost leak you use this to pressurize your entire intake system from the turbo all the way through your intake manifold. You hook up he 4" side of the tester on the turbo intake, you use compressed air and pressurize the intake system and look/listen for the leak.

I think somebody posted a picture in one of the threads

 

here is mine Dr. Thunder bottle from walmart and a 3" dia. exhaust pipe with end welded shut and a 1/4in flare fitting in the center. Oh a couple of raps of duct tape to make the Dr. thunder bottle to fit snug with a hose clamp. ED





found a leak in the lower passenger side boot.

 

$10 bucks worth of misc plumbing stuff from the local hardware store and here you go. It's found leaks on a whole bunch of trucks to date and keeps on ticking.

 

you can use the 4.5 in size. you just crank the clamp down a little more.

 

Have you tried this? I don't mean to question your intelligence or offend you, but .5" seems like a lot to suck up without creating creases and air leaks. Parts are cheap enough. I guess I could give it a try.