Turbocharger Waste Gate

[floydfowler]

I have a question about the Holset HX 40W turbo.  What is the function of the internal waste gate?

I have posted about my problem of losing boost pressure after using the exhaust brake. I have  ordered  a new brake from Pacbrake which supposedly has much better braking performance although I followed posted advice and tested the old one  by powering the 12v solenoid and confirming the arm snapped on and off freely.

I am now wondering if my problem could be this diaphragm actuated waste gate.  I tried unsuccessfully to rotate it by hand but have not removed the linkage yet to try it again. I have also removed the front inlet duct on the turbine and confirmed the shaft has no perceivable side or end play. 

After using exhaust, engine loses all power and boost pressure and I see black smoke from exhaust. I can pull over for a few minutes and all is good to go again!

[dickandlois]

Floyd,  the HX -40 is setup like my HX-35,  with the exhaust brake not releasing thing will get hot real fast. NOT Good.

The exhaust gate for the turbo needs to be free to move. Super Lub. it but the location makes it difficult to get to in most cases.

The 12 volts operates an air piston that moves the pakbrake.  The mechanical pivot points need to be lubed frequently or they seize up. 

Use Super Lub. sold by Cummings and others in small bottles.

Not keeping things free can add up to some expensive repairs.

Rich.

[floydfowler]

Thanks Rich.  The exhaust brake moves very freely when I apply power to the solenoid, in fact, it snaps back and forth with momentary 12v applied so I'm thinking it is releasing. I have lube from Pac brake coming with the new pacbrake. 

Still wondering about the diaphragm actuated internal waste gate on the turbo.  I have soaked it with penetrating oil and will try to get it moving by disconnecting the linkage.What is the purpose of the waste gate?

 

 

[dickandlois]

1 hour ago, floydfowler said:

Thanks Rich.  The exhaust brake moves very freely when I apply power to the solenoid, in fact, it snaps back and forth with momentary 12v applied so I'm thinking it is releasing. I have lube from Pac brake coming with the new pacbrake. 

Still wondering about the diaphragm actuated internal waste gate on the turbo.  I have soaked it with penetrating oil and will try to get it moving by disconnecting the linkage.What is the purpose of the waste gate?

Floyd, from your last post it sounds like you have access to the control module, kind of s simple setup, but there is a rather strong spring inside the pressure module.

 The turbo spools up and as it does a small portion of the air is diverted to the mentioned module. 1-lb. of air equals 1 inch of boost. setting the max. boost to match the specifications for the engine is important. Too High and that could and will cause damage to the engine. 

The little wast gate paddle needs to be free. Rust builds up from sitting - that is the biggest issue.  The other big one is damaged turbo compressor vanes and coke buildup in the turbo bearings due to oil breakdown - caused by stopping a hot engine to soon after a full throttle run uphill. The temperatures can easily exceed 1200 degrees.

Hope this helps and clears up how this style wast gate works.

The New VGT setup is similar, but mechanically different, if that makes any sense.

Rich.

[floydfowler]

 

2 hours ago, DickandLois said:

Floyd, from your last post it sounds like you have access to the control module, kind of s simple setup, but there is a rather strong spring inside the pressure module.

 The turbo spools up and as it does a small portion of the air is diverted to the mentioned module. 1-lb. of air equals 1 inch of boost. setting the max. boost to match the specifications for the engine is important. Too High and that could and will cause damage to the engine. 

The little wast gate paddle needs to be free. Rust builds up from sitting - that is the biggest issue.  The other big one is damaged turbo compressor vanes and coke buildup in the turbo bearings due to oil breakdown - caused by stopping a hot engine to soon after a full throttle run uphill. The temperatures can easily exceed 1200 degrees.

Hope this helps and clears up how this style wast gate works.

The New VGT setup is similar, but mechanically different, if that makes any sense.

Rich.

Rich, 

Sounds like what I assumed to be a vacuum diaphragm is actually a pressure diaphragm/module.

[dickandlois]

Floyd. 

 

Sounds like what I assumed to be a vacuum diaphragm is actually a pressure diaphragm/module.

       Yes it is a pressure activated diaphragm .

You got the gold ring while on the Carlisle  ride.

Rich.

[rayin]

Before spending money, soak the waste gate in carb cleaner for a while, if that doesn't make it work as designed, get out your wallet.Banks makes an excellent Big Head wastegateto fit your engine, and explains everything clearly on their webpage.

[wolfe10]

We still need to provide "how to test" info.  Since I have not had a turbo failure in more than half a million DP miles, I have no first hand information.  But am sure someone else can give the "step by step" for testing.

Thanks.

[dickandlois]

Ray, The thing is not as expensive as you might think.

With a factory unit that come preset to the max pressure and one needs only to install it before removing the spacer. makes it much easier.

Rich.

[dickandlois]

Set up and test requires a air supply connected to the input with a pressure regulator one can very from 0 psi to the max air(turbo) pressure that Cummings specifies. up to 30 psi is the range  I would use unless.  Engine can very some in regards to high boost point.

As a side note ! the module should include a new length of silicon pressure line and clamps. Might want to as though it is not a standard auto parts store item.

Brett  do you know where  this info should be included?

Rich.

[rayin]

This Holset Wastegate Failure Diagnosis flow chart can help find your problem. As other replied, "seized wastegate valve-open position" is the usual cause. Your's appears to be sticking momentarily-on the verge of total failure. As they said, carbon-ed up or rusted.

[dickandlois]

Thanks Ray, that is the chart not in my file. LOL

Rich.

[floydfowler]

Thanks for all the good information.  I have soaked the gate shaft and connections with penetrating oil and will have a go at moving it tomorrow.  If I should need a new turbo (HX40                      w) can I install it as it is delivered or is there special adjustment needed?

[floydfowler]

Opps, I see Rich has already covered that!

[dickandlois]

1 hour ago, floydfowler said:

Thanks for all the good information.  I have soaked the gate shaft and connections with penetrating oil and will have a go at moving it tomorrow.  If I should need a new turbo (HX40                      w) can I install it as it is delivered or is there special adjustment needed?

Kind of depends on who you get it from. Cummins is generally preset from others it is not preset as they do not always know the engine serial number and the matching set up distance of travel per the engine application.

Rich.

[jleamont]

To test it you need a Magnehelic gauge bar. Looks like this (photo below). First step is to know the pressure spec required. That has a hand pump on it that is connected to a gauge.

Without the specs you can unhook the actuator, make sure the valve operates freely in the turbo housing. Vacuum test the diaphragm to make sure there are no leaks. If those check out the control needs to be checked. For that the proper software with a scan tool would be needed.

In most cases you can over take the engine and actuate/manipulate the inputs and outputs and see if boost changes.

If you can just simply swap the turbocharger depends on the year of the engine. 

[floydfowler]

UPDATE

Good news! waste gate rotates very freely though only for about 30 degrees.  Bad news, "e" retaining  ring left the planet when I finally got it off. Looks like about 1/4" ring but I'll try to get caliper on the shaft to be sure. Also, reattaching actuator arm is a real pain from underneath the coach.

I should have the new pac brake on by Thursday and can't wait to test drive it.

[floydfowler]

Still lose turbo boost after using exhaust brake!   The new PacBrake works great but after turning it on,slowing down and turning it off, I still  have no boost pressure and the engine has zero power.  I finally convinced the DW to ride in the back with the access cover open to observe the brake actuator cylinder.  She confirmed that the cylinder actuates the exhaust brake but when I turn the brake off the cylinder does not open the brake.  I have tested the air switch/solenoid and I know it is operating properly.  I must pull over and put coach in  neutral and set park brake.  After a few seconds, I can depress the accelerator and see that boost pressure is back working.  Drive on fine as long I don't use exhaust brake.

I am thinking the problem lies somewhere with an electrical switch, relay or sensor.  I think I have a throttle position sensor that overrides the exhaust brake  if the throttle is depressed. Whatever the problem, when I turn the brake off, the solenoid isn't getting the signal to release the brake.  It is also tied in to the Alison transmission somehow.  I am not getting any codes. 

A wiring diagram for Pac Brake circuit  for 2001 Holiday Rambler with Cummings ISC 350 would be most helpful if anyone has such a thing.

😞

 

[wolfe10]

What is the exhaust brake "pre-select gear" (left or only window in Allison shift pad) when you turn on the exhaust brake?

When you step on the throttle, does it stay with that gear indicated OR does it go back to "6"?

Same problem if you turn off the exhaust brake switch?

[floydfowler]

Not sure.  When I turn brake on, it stays in 6 until coach slows down and then downshifts.  Slowing more  and it will downshift again.

I will need to get it on the road again to get your answers but I will not be able to do that until Sunday.

Thanks for your reply.

Floyd

[wolfe10]

With a ONE window Allison shift pad, the gear indicated is the "pre-select gear" (the gear toward which it will shift when it will not over-speed the engine).

With a  TWO window Allison shift pad, the left window is as above, the right window the actual gear you are in.

This will tell us a lot as to whether there is a mis-communication in the electrical signal to the exhaust brake.

[floydfowler]

On 5/31/2019 at 9:08 PM, wolfe10 said:

With a ONE window Allison shift pad, the gear indicated is the "pre-select gear" (the gear toward which it will shift when it will not over-speed the engine).

With a  TWO window Allison shift pad, the left window is as above, the right window the actual gear you are in.

This will tell us a lot as to whether there is a mis-communication in the electrical signal to the exhaust brake.

I have only one window and it goes from 6 to 2 when turn on the exhaust brake, and downshifts twice as I am slowing down.  
Good news! I finally studied the wiring diagram ( with a magnifying glass as the print is tiny) and was able to locate two Omron 7866 relays for the exhaust brake in the front panel. I switched then with two borrowed from other positions (panel has 5 or 6 of the same relay) and took the coach for a test drive.  Turbo boost works fine now after using the exhaust brake. One or both of the relays was sticking and both are now in the trash with four more coming from Amazon.

We are ready to hit the road again!😋😎

Many thanks for your time and assistance!

 

 

[jleamont]

1 hour ago, floydfowler said:

I have only one window and it goes from 6 to 2 when turn on the exhaust brake, and downshifts twice as I am slowing down.  
Good news! I finally studied the wiring diagram ( with a magnifying glass as the print is tiny) and was able to locate two Omron 7866 relays for the exhaust brake in the front panel. I switched then with two borrowed from other positions (panel has 5 or 6 of the same relay) and took the coach for a test drive.  Turbo boost works fine now after using the exhaust brake. One or both of the relays was sticking and both are now in the trash with four more coming from Amazon.

We are ready to hit the road again!😋😎

Many thanks for your time and assistance!

 

 

Great troubleshooting! Glad you are all fixed up.