As I have been posting, I have been dealing with a whistle in my truck. I towed heavy today, and it whistled a lot. Once I got home and let the truck cool down a little, I did some searching. I can not move the wastegate arm or the shaft all. With the engine off, of course, shouldn't I be able to get some movement in the arm or the shaft, or is it supposed to have no movement to it? I haven't pulled the wastegate off yet to check it, because I haven't had good weather or time.
So, if someone could explain to me how a wastegate works, does it use vacuum or forced air to actuate the valve, and how should it be behaving if it works properly, I would be very appreciative. Not only do I want to understand, but I want to know if this is where my problem lies. Thanks, in advance.
Mark

 

They have a STRONG spring in them! Moving them by hand would take more than the strength of a normal person.

 

OK- that helps.
The flapper itself does, or the actuator?
I plan on removing the wastegate and testing it.

 

The actuator has the spring. The flapper will swing freely when you remove the actuator.

A general way to test the actuator is to connect a vacuum line to it and blow in it. If it holds your pressure then chances are the diaphram is good. If you want to get more technical then you can remove it and connect compressed air to it (don't use the full pressure of the compressor, you'll blow the diaphram; 30psi should be plenty to tell you if its working).

 

If you disassemble the wastegate, the flapper should be easy to move, one finger should move it. The actuator is pressure activated and 20 psi should fully move the plunger.

 

wistle is usually a leak on the high pressure side. i have heard it on the low pressure side if the filterminder broke or came off. you may have to make a fitting and connect it to the turbo where the hose from the filter is now and pressure it to 20 psi i think you will find it fast.

 

I can just about promise you your whistle has NOTHING to do with the wastegate or actuator. Very reliable device. The weakest part is the little hose that goes to it, which is very easy to check.

Boost leaks are usually pointed at first, but often what causes irritating whistling is a preturbo exhaust leak. The manifold and turbo gaskets are steel and very thin and can act like the reed in a musical instrument if something is loose or warped.

The way the wastegate works is pressure from the intake side pushes a diaphragm to overcome a stout spring. The spring pushes the rod and lever that keeps the wastegate closed. The gate itself somewhat resembles an engine valve with the stem cut off. A pivot on it connects it to the a lever which joins to the lever outside that you can see via a shaft. This valve closes off a port on the pressure side of the exhaust to the tailpipe side of the exhaust.

When the intake pressure gets high enough, the diaphragm overcomes the spring and allows the gate valve to pull away from the port and some of the exhaust pressure can bypass the exhaust fan in the turbo.

 

I had a whistle on a turbo car be caused by a WGA. There was a small crack in the body. I agree that it's rare, but not impossible. I second the notion to look toward the charge piping.

 

Pet peeve of mine. A fan takes a rotary force to move a gas. A turbine takes the flow of gas to turn a shaft. The same, but opposite.

 

check all intercooler boots, and the intake manifold gasket, best to build a homemade boost checker and pressurize the intake system, this will help find and fix the leaks

here is a link to what you need to do

https://www.dieseltruckresource.com/...r-t214239.html

 

Boost gauge lines with a small leak most often caused by getting kinked on installation can make a pretty good whistle too.

 

mine was the intake manifold gasket. Easy fix

 

I have made an adapter to test the high pressure side, and no whistle there. I have replaced the intake gaskets on the intake horn, whistle still there. It whistles at high boost, but when it does whistle, I don't loose performance. The job I am working on now has me climbing some really steep inclines (driving to and from), so I am getting some good time in hearing it and trying to pin it down. If I back off the pedal some, it will go away. It also has two pitches, and changes intermittently.
Although it is unlikely to be the problem, my next step is to disconnect the short hose to the hard line for the wastegate, plug and clamp it, and see what happens. If the wastegate is working, then I shouldn't loose any boost, since the spring will keep the flapper closed, correct?
The whistle comes and goes, too. Some days, I can pull the truck hard, and it won't do it.
By the way, thanks a ton for all of your input and wisdom, and don't stop posting it- sooner or later, I will find the issue.

 

So- I pulled the short hose off of the wastegate line, and put 20 pounds of pressure on it. The wastegate is working fine. So, I pulled the short rubber line off (the clamp was pretty tight, but the line was not very tight on the tube), and replaced it. I drove it this evening, and pulled some moderate hills with the pedal to the metal, and I couldn't get it to whistle. So, here's hoping that it is solved. I am not getting my hopes up, but if it stays gone for a couple of days, I may get optimistic.

 

does your tool also pressurize the turbo housing ? or does start right after the turbo? also you might try pressurizing the exhaust system to see if you can get the gaskets to act up