Fallfork

I have no turbo boost pressure. 0 psig up to 2500 rpm and then no more than 5 psig by 3000 rpm. Measuring boost with a mechanical gauge. Mounted the gauge direct to the manifold to eliminated possibility of a kink in the gauge supply tubing - still no boost. Checked gauge with compressed air, and it appears to be functioning properly. Truck will get up to highway speed, but it takes forever. No check engine light. No codes. I pulled the intake to the turbo and there is no puddle of oil that would make you suspect a blown turbo seal/bearing.

All charge-air-cooler boots appear to be intact and all clamps are tight. I am assembling the fittings necessary to pressurize the intake - does anybody have a method for capping the turbo inlet so I can run this pressure check?

If there is no intake leak, what else do I check? Is it possible the waste gate is stuck open - and how does one evaluate that?

Thanks for you help in advance!

2002-5.9

Plumbing department at Home Depot has everything you need. These homebrew testers work well. Search "boost tester" for more.

Junk Man

I put a shut off valve on mine. That way I can turn the air lower than my air tank would allow. 4" boot is the closest to the turbo size.

Fallfork

Ah... that looks pretty simple. Off to Home Depot tomorrow. I'll keep you posted on what I discover. Thanks to Junk Man and 2002-5.9!!

rebal

are you driving the truck when checking boost?
if your sitting in the driveway you will barley see any
a good place to look for leaks is down at the lower hoses, the fenders can rub holes in them,most guys bend the fender lip away from the boots

Fallfork

I am checking boost in the driveway, so I'll get on the road. Rigged up a leak tester this afternoon. The lower boots needed to be tightened a little bit. The big discovery was that my wastegate actuator is blown and therefore leaking like crazy. I did find one other spot - there is a hole in the back of the intake air horn. It is drilled into a boss that looks like it is cast in the bottom of the air horn. The hole is plugged with something plastic, but it leaks. Is this hole supposed to be there or is it a present from a prior owner? If this is a factory hole, what is supposed to be in the hole that would keep it from leaking? Thanks!

Fallfork

Just went for a drive with the wastegate actuator hose pinched off with a visegrips. Still can't get boost pressure above 8 psig at WOT. Wonder if the wastegate is stuck open??

Fallfork

And any insights on how you get the c-clip of the wastegate actuator rod would be greatly appreciated

rebal

small sharp screw driver for the clip and you should be making 15 psi minimum .if the waste gate is stuck that will lower boost. also the hole in the intake should not be there .

Fallfork

Do you push on the end of he "C" or do you wedge the screwdriver between the pin and the center of the "C" ?

nickg

either way will work, likely it will go flying so be careful, if room use needle nose pliers to pull the clip off

Junk Man

I put my boost boot on the front of the turbo & connected to the air (approx 25#). My leak was from the intake cover next to the lift pump bolt. The gasket was old, brittle & let go. It can leak from any of the plumbing boots, the intake cover or the intercooler if there is a crack. Local shop says that you won't damage anything by driving with a leak. If you can hear the leak, it should be obvious where it is.

Fallfork

Thanks to nickg, I switched to a small awl and the c-clip went flying. I had already written off the c-clip mentally, so I wasn't too ****** when it disappeared With the actuator removed, I was able to determine that the wastegate moves freely, so a stuck wastegate is not part of my problem. Nice of Cummins to, once again, put their part number right on the actuator - so at least it isn't difficult to order a stock replacement.

madhat

Have you tried spraying soapy water all over the path? If there is a leak, it may bubble up. Just do one part at a time...

Fallfork

Check out these photos of my air horn. There is a sizeable leak coming from the drilled boss at the bottom/back of the pipe, which is currently plugged with some sort of torn-off piece of plastic. What the heck is supposed to be in that hole ? Do I drill out the plastic junk and hope there are some threads that will accept a proper plug?