Engine/Transmission (1994 - 1998) Wastegate actuator problems

[dcasselberry]

I'm losing boost on the high end of things and finally narrowed the problem down to the wastegate actuator, which is sticking in the open position. I haven't had any luck locating that part locally yet, though we do have a Banks distributor who sells the "Banks Big Head" actuator. It is pricey, but since I haven't even been able to find a price on the Cummins part, much less locate one, I'm leaning toward buying the Banks part. Guess I'd like some advice on which way to go with this.



The dealer told me that they don't replace wastegate actuators, they replace the whole turbo. While I'd love a new turbo, I'm not quite ready to take that plunge yet.



Also, does anyone know the procedure for changing this part? Is it complicated or simple?

 

[Deezul1]

Before buying a high dollar Banks kit try fastening the wastegate closed mechanicaly. I ran a long time with mine disconnected before switching to a non waste gate 16cm housing.

 

[Strick-9]

If you remove the turbo, wastegates are very easy to change. On the truck, they can be tough.



If the wastegate is sticking in the open position, then you should have a great deal of turbo lag. Have you noticed the truck being very sluggish on takeoff? If not, I doubt the wastegate is hanging open.



The easiest thing you could do would be to remove the turbo and then remove the backplate that the downpipe clamps to. This will expose the wastegate. You can then verify if the wastegate is closed or not. You can apply air pressure to the wastegate line and actually watch the wastegate operate.



Over time the springs in some wastegates get softer. This causes them to open sooner. You can adjust the rod a revolution or two tighter to apply more clamping force on the wastegate.



This will be much more clear once the turbo is off.



Hope that helps.

-Chris

 

[grtescpa]

Originally posted by Strick-9

If you remove the turbo, wastegates are very easy to change. On the truck, they can be tough.



If the wastegate is sticking in the open position, then you should have a great deal of turbo lag. Have you noticed the truck being very sluggish on takeoff? If not, I doubt the wastegate is hanging open.



The easiest thing you could do would be to remove the turbo and then remove the backplate that the downpipe clamps to. This will expose the wastegate. You can then verify if the wastegate is closed or not. You can apply air pressure to the wastegate line and actually watch the wastegate operate.



Over time the springs in some wastegates get softer. This causes them to open sooner. You can adjust the rod a revolution or two tighter to apply more clamping force on the wastegate.



This will be much more clear once the turbo is off.



Hope that helps.

-Chris

A quick question: When I had my exhaust manifold apart I noticed that I could not move the counter weight

on the waste gate. Can it be moved by hand to check it or do I need to apply air pressure?

 

[illflem]

I'm with Chris, it doesn't sound like the wastegate is your problem. But if your wastegate truely needs to be replaced a Banks installer is a good place to look. Many folks who have the Banks kits installed leave the OEM parts with the installer, they just don't have any use for them. Good source for stock exhaust parts also.

 

[dcasselberry]

Thanks for all your input. Yes, there is turbo lag on takeoff. We did use air to pressurize and the diaphram indicated movement. Drove the truck afterward and my boost seemed normal again, achieving about 29psi at WOT. Then, the next day, it was back to square one, and I can't get over 20psi now. We tested the lift pump and it showed a consistent 25psi. I could certainly be wrong, but i still suspect the wastegate is sticking, since things were normal again after the introduction of compressed air, only to revert to problem status again later. The overflow valve seems to be functioning properly, and we checked the fuel filter so it's not bad fuel or a clogged filter.



Anyone have other suggestions as to what we may have missed?

 

[GOakes]

I know enough about this to be very dangerous --- but I’m just foolish enough to throw in my two cents worth.



First penny: Chris Strickland knows where of he speaks --- listen to him…



Second penny: My 97 model had been slowly loosing power for some time. The loss had been so gradual that I failed to recognize it until it was hitched to an eight thousand pound trailer. There a long string of events that followed including a 1200 mile trip to the mountains and some tough times getting up a Colorado mountain pass that prompted me to dig in to the problem. I don’t know anything about diesels or turbo chargers but I did have a service manual with instructions on the test and adjustment procedure for the turbo waste gate actuator. I removed the turbo charger and put in on the bench (just like Chris said). I spent more than twenty-five years in electrical testing and repair, that experience taught me to be careful and recheck any and all test findings. What I found worried me so much that I did three “As Found” test sheets. My waste gate actuator was so far out of adjustment that boost pressures were 30 to 40 percent below where they should be. It took two full turns of the adjustment on the actuator rod to get things back into spec. I took the truck out on the highway today and renewed an old acquaintance, “power and performance”.

It’s important to caution that this is just one incident and one turbo charger and it may not apply to any other situation. Based on nothing but a guess, I’m betting that it was all due to a weakening of the spring in the waste gate actuator. This device has never been touched by anyone sense the day it was delivered to me (new) in September 1997.

Your truck is a 96 model and may not use the same testing and adjustment procedure as the 97 model so I don’t want to muddy the waters by offering any thing more, except to say --- If your actuator is replaced or any adjustment is made to the existing unit you (or someone) will to have to check it out against some standard or specification. --- Unless you know a whole lot about the Cummins B5. 9 and satisfactory modifications to that engine, or you are willing to run the risk of damaging something, follow the Dodge/Cummins procedure for your year model.





Old georg

 

[dcasselberry]

A big thanks to everyone who offered advice.



In the end, it did turn out to be a faulty wastegate actuator. As soon as I replaced it, everything was normal again.



It is great to have so many knowledgeable and helpful folks here to help folks like me troubleshoot problems and find solutions.



Thanks again!

 

[drrhoades]

dcasselberry,

Did your truck seem to start building boost around 1900 RPM and after that only till about 2500. That is what mine is doing and I was just wondering if it is the same problem. I dont have a boost gauge yet so I am still guessing.



Thanks,

Doug

 

[dcasselberry]

Doug:



My truck became a slug on both low and top end... ... at WOT it would barely reach 20psi... ... then drop off quickly. A boost gauge will be a big help to you..... I'd make gauges a real priority... . I certainly swear by them..... and I'm no expert so I'd be hard pressed to say that the problems you're experiencing as the same as what happened for me. The more data and description of symptoms you can post here about your truck problems, the more likely the real knowledgeable folks here on TDR will be able to help you troubleshoot. Good luck in getting your truck back in order.

 

[drrhoades]

Thanks for the reply. I am hopefully ordering gauges today so I will be able to tell more.

 

[Andy Redmond]

part number for actuator

The cummins part no for the actuator is 3533948 (likely superceeded by now). It should work on all 94-early 98 12v's with the HX 35w. Exceptions may be the 96-98 12v 5spd trucks as they had a higher oe boost specs.



Good luck,

Andy

 

[drrhoades]

Well I got gauges and I have found that I can make 23 or 24 lbs(iI get out of it at that point and slow back down) or boost on a supposedly stock truck, which from what I can tell it is. Could it be that the wastegate is stuck closed. Boost doesnt build until around 1800 or 1900 rpms and on the highway at 70 I am running 6 lbs. What should I look for to check this out. Is it bad to have the wastegate stuck closed.



Thanks,

Doug

 

[bubba_zanetti]

The purpose of the wastegate is to allow the turbo to build a lot of pressure early (low RPMs), without blowing up the engine as more pressure becomes available.



In other words, the wastegate will remain closed as boost is building. At a pre determined point, the wastegate opens and is fully opened at max boost (20 psi for stock trucks)



So as boost is building, your available boost pressure is already bypassing the turbo and heading out the exhaust.



If the wastegate stays closed (frozen, unhooked, or whatever) then the only thing limiting your boost is the turbo itself... (under most situations the stock turbo can only produce about 30 psi max... from what I have read here)



If your wastegate is frozen open, then boost will only build at the highest rpms... and is limited to stock setting (about 20psi).



Also remember a small turbo housing spins up faster, produces boost earlier, but has a low max boost available. A large turbo housing spins up much slower, but has a much higher max boost available.

 

[Cooker]

Wow, this is dragging up an old post from the dead