Engine/Transmission (1998.5 - 2002) Low Boost, can't find leak

[TWilkening]

I've had problems with low boost on my truck. It will only hit around 12 PSI WOT. I rigged up a tester to go on the intake of the turbo. I had the system up to around 12 psi and still can't find any leak. One of my lower IC boots had a slight tear (which ended not going clear through), and I replaced both with new boots from PDR. I can't feel any leaks, and the only noise I can hear is air going past the rings. I would think if I'm losing that much pressure, the leak should be fairly easy to find. I've checked it with the air filter off, and it made no difference.

Any ideas?

 

[MMiller]

Unhook and cap the air piping at the intake. I just used some 3" exhaust pipe and welded a flat plate on it. Run it up to 15-20 psi and use soapy water. I have a cap made with a valve stem in it, I can air up an aftercooler just like a tire. If it holds, all is good.



Do you have black smoke, high EGTS? If not, maybe something is wrong with your fuel system, and its not fueling enough to build boost.



Michael

 

[TWilkening]

I don't seem to have any more smoke than usual, but egts are running 50-100 warmer driving down the highway. I don't have any codes, and I still have good fuel pressure. I'll try hitting the intake with 30 psi and see if I can find anything.

 

[Mad Bomber]

All the bolts should be at 95 INCH LBS. Make sure to check all 9 bolts (2) on every boot and at the bottom of turbo. Also new gaskets on intake horn at the grid heaters. It also could be loose manifold bolts.

 

[DCreed]

the HY has a tight housing check the waste gate sounds like its stuck open.

 

[TWilkening]

What position should the wastegate be in?

 

[DCreed]

fully retracted as boost pushes it open.

 

[TWilkening]

I guess what I meant is which way should the bracket that attaches to the arm be orientated. Can I normally move the waste by hand? It shouldn't hurt anything if I put a pair of vise grips on it and move it by hand, should it?

 

[DCreed]

be VERY carefull !! the pins that hold the arm on are hardened and fracture easily. you can also test by putting a hose on the gate's inlet and putting pressure on it to see when it opens. or try a short run with the gate hose unhooked to see if it will hold. dont push too hard(psi).

 

[TWilkening]

I checked it out and it moves freely. I tried moving it the other direction and it didn't go any, so I think it is free. The wastegate is hard piped on a HY, so I can't undo the line. I'll pump it up and whip out the soapy water.

 

[DCreed]

if it moves with little/no resistance ,that is your problem. there is a spring inside the wastegate "can" that holds the gate shut, if it is weak/broken it wont hold.

 

[Bob4x4]

the w/gate actuator can be removed fairly easily,and be tested with regulated air.



Bob

 

[KLockliear]

BE CAREFUL if you pressurize your IC system. Keep your body and everything else away from the caps. 15+psi will blow that thing across the yard.



You only need 10psi or so to look for leaks with the soapy water. As mentioned, cap the IC tube at the air horn, and make another cap with a hose fitting in it for the other side. May even been the IC itself leaking, not necessarily only a hose.

 

[Bob4x4]

I have a safety chain on mine in case something should slip. There are cases where leaks only show at higher pressures.



Bob

 

[2-ND TIME]

Low boost

Does your engine sound tinny when it is under power? If so sounds like a fueling problem? Mine has been doing this since new! Have one of the dollarshops put the drb as an oscilloscope and have them inspect the signals to the vp44 this will tell fueling. Mine has always fueled at about 70%. IT starts to fuel at about 1450 and by 1975 rpm it is running out of fueling.

 

[DCreed]

2-nd time, have you had the timing checked? that causes the most rattle.

 

[TWilkening]

Okay folks I found the problem. I feel like a blooming idiot, but will share so others don't make the same stupid mistake. Got home from work figured I'd pressurize. Aired it up to around 5 psi on the boost gauge. As usual, heard no leaks. Was sitting in the cap watching the pressure slowly bleed off, and figured I'd pull the boost gauge out just to see. I pull the gauge out, and what do you know, the line has a sharp kink in it, right at the gauge. I straighten it out, and gauge instantly jumps to 20 psi. Thinking about it now, I'd hate to see how much pressure I really had on it when it showed 15 on the gauge Took the truck for a drive, and wouldn't you know it, gauge shows normal pressure.

Moral of the story: Look for the easy stuff first. Now I need to find a new brass fitting that crimps on to the hose. Any idea where to get one?



Now I'm gonna go throw on the J-hook I got when I got the boots from PDR. The factory ones were kinda crappy looking and the one was about worn through, so I get it wasn't a complete waste.





Lord I'm an idiot

 

[DCreed]

its a 1/8 brass ferrule cheap and common. dont over tighten on install or you'll be doing it again.

 

[2-ND TIME]

Low boost

Guess that you are using air lines for air brakes are you. They have the little brass fural that goes over the air line and tighten it up. Maybe you are using the hose clamp style? Just use air line tubing ( is it 1/8") at any of the hiway truck shops and even Napa and stores linke that should have the hose and brass ends that you need? and then plumb it to what you need size wise?



To answer the one previous, yes the timeing has been checked but if you say what the voltage looks like no wonder the engine doesn't run very well. I have copies I made for the different signals if you are curious what the look like. Maybe email or fax them some to you. They are very bad!!! Thanks