Every time I step on the throttle, I hear a loud hissing sound, and I'm not getting the full amount of boost I usually get. I've looked at all four of the rubber hoses on my turbo plumbing, and all appear to be intact. Just sitting in the driveway, I can't get it to build any boost so I can pinpoint the leak. Short of putting a midget under the hood, and hauling a heavy load up hill, HOW DO I FIND THIS LEAK?!?!?!?!?
I pulled 22,000# of limestone yesterday, and my fuel mileage sucked, and I was down on power.

 

Take the boot closest to the turbo off at the turbo side. Messure the inside diameter. Go to local hard ware store get a peice of pvc pipe to fit in it, get a end cap for it, then you can either drill a hole and put a valve stem in it or an air hose chuck so you can put air in it. You stick the other end of the pipe in your intercooler boot and tighten it up. Make shure you glued the cap on, fill it up with 15 20lbs air press and listen for the leak or suirt the rubber boots with soapy water/and the intake horn where the grid heater is.

 

Spray down the air system with a soapy water mix and look for the bubbles.

 

a bunch of plumbing fittings from Home Depot and you get something like this.



Other than removing your intake hose, you don't have to disconnect anything else. Pressurize the whole intake tract, intercooler and the motor itself, your leak will show up.

Jeff

 

Homestead hit it right on the head, spray soapy water on the boost fitting hose and all the intercooler hoses, you will hear it hiss if it a big hole

hope this helps, boost leaks can be very frustrating

 

Boost leaks can be very frustrating. You will hear them if you have one, the trick is finding it.

I chased a major leak for almost 2 months. With the above tester, I was finding a pin hole leak here and there, a leaking intercooler, a leaking intercooler boot, and when we figured we had finally nailed it, found out the boost is going up the valve guides and pressurizing the valve cover. Time for a new cylinder head!!!!

Wasn't to impressed at all but I did find the boost leak LOL!!!!

Jeff

 

Good idea, Homestead.

What about the pressurized air vis-a-vis the valve timing? Do you just find a sweet spot in the firing order, or is there not enough overlap in the cam for it to matter?

I'm getting ready to set the Hobbs switches for my H2O/CH3OH system (which has a Schrader valve for adjustment), so I'm curious about the engine-off bleed air action.

 

XLR8R

I had the same questions come to mind about this. I was dealing with Mark at PDR at the time while chasing my leak and he told me you don't have to worry about with the Cummins.

When you pressurize the whole intake tract and motor to about 25-30 psi, it will hold for a good 30-40 seconds before it bleeds off. That is more than enough time to hear a leak. You can also do what I did and hook you compressor to the leak detector and set it's regulator to 25-30 psi. If the compressor is far enough away so it doesn't interfere noise wise, it can continuously feed air into the motor while you soap everything as well as listen for a leak.

Jeff

 

Thanks!

We can just leave the air chuck from the shop compressor hooked up and set the Hobbs switches accordingly.

 

Homestead,
I see, from your picture above that you have 2 pyros hooked up one pre-turbo, and one into your e-brake. I'm curious what is the steel line conection for on your e-brake, just after the pyro probe. My setup is similar except I just have the post-turbo pyro probe.
thanks, Joe

 

Hey Joe

That steel line you see is for my brake pressure gauge for my exhaust brake. Just out of the picture it turns into regular nylon boost hose and heads into the cab. The hard line just dissipates a bunch of the heat so it doesn't melt the line.
Actually, this is the same setup you would stick into you pyro port if you wanted to measure drive pressure to your turbo. The way mine is right now, if I really hammer on it while under load, my brake pressure gauge actually shows an exhaust restriction of 2 psi.

Jeff