Turbocharger wear

[Joe Rhea]

I have a friend that has a C-9 engine. In the process of trying to find a squealing noise located in the engine area they removed the hoses from the turbo and observed shinny spots where the impeller had been hitting the sides. They checked for shaft movement and found what was thought to be excessive. They started the engine and then observed sparks on deceleration. The turbo was removed and taken to a local rebuild shop. The cost of rebuild was around $500.00 opposed to 3k that Cat wanted for a new unit. His Cat mechanic told him that the excessive use of the pac-brake contributed to the early failure of the turbo with approximately 35K mileage. Excessive meaning that his used his Pac-brake in nearly all stops. My question to the forum is this a correct assumption on the use of pac-brake?
The squealing noise turned out to be the purge valve on the bottom of the drier was not sealing off completely.
Thanks Joe   

[Bill Staley]

Our previous Motor Home had a C9 in it and we put about 75,000 miles on it.  The Pac Brake was never turned off.  The turbo checked out fine when we sold it.  What I was told by the mechanics was that the most important thing was to give the engine at least 6-7 minutes of basically idle time after being on the road for the turbo to cool.  Other wise it would experience excessive wear.  Don't know if that would cause this problem.

[Steve Huber Co-Admin]

Joe,
Do you know if this was a 400HP or 425HP? 425s were used mainly in 08 and 09.
Steve

[Joe Rhea]

Steve it is a 08 model and a 425 HP Serial #9DG09884
A big problem Ron had was finding the gasket between the turbo and pac-brake. Cat does not have a part number for it, it is considered a after market product. The Cummins part # is 2866337 for those that are interested.

[Steve Huber Co-Admin]

Joe,
Turbo problems are fairly common on the 425HP C9s. CAT apparently had a design issue.
Steve

[Dave Atherton]

Joe, use of PAC Brake all the time is used by many members but problems will happen both
With engine and road conditions. It is not recommended to use the engine exhaust brake or
PAC brake or engine compression brake all the time. Build up of heat in engine that is retained
heavy usage on/off, on/off etc. the little piston that activate the pac brake is not built to with
Full time usage. The pac brake is only effective at 45 mph and less because engine exhaust
pressure will open the flapper. The turbo charger rebuild is fine as long as same value spec’s
meets engine OEM spec’s, found this to be a big problem with turbo charger replacement. Air/
fuel ratio will change operation of engine with ECM if value on turbo is not the same spec’s.
It is each owner call as how to drive and maintain his engine, I’m just bringing out from technical
information that advise not to use practice. Dave Atherton Retired Cat Mechanic

[Dave Atherton]

Steve you are correct on the Cat C-9 425 there has been many turbo problems and driving
with pac brake on all the time is main reason problems happen on the road. Reason for this
along with retaining exhaust heat, then there is a carbon buildup on the turbo sliding ring
that service as turbo wastegate not letting all exhaust gas to exit turbo housing. Than carbon
buildup will plug openings in sliding defuzer and sliding ring movement will be restricted.
What happen next power loss, heat buildup. Gasket failure on housing is a real good indicator
about excess heat build up. Dave Atherton Retired Cat Mechanic

[Stan Simpson]

Dave and Joe,
Just to be clear, you are referencing a PAC brake and not the exhaust brake I have on my C9 400? Yes?

[Joe Rhea]

Yes we are referencing the Pac-brake 

[Stan Simpson]

Yes we are referencing the Pac-brake

Curious, we have the same model coach. Wondering why you have a PAC brake and I have an exhaust brake? Optional?

[Steve Huber Co-Admin]

Stan,
When CAT came out with the 425HP C9, they also incorporated the variable geometry turbo exhaust brake. Prior to this (400HP) they used the Jacobs exhaust brake.
Steve

[Stan Simpson]

Stan,
When CAT came out with the 425HP C9, they also incorporated the variable geometry turbo exhaust brake. Prior to this (400HP) they used the Jacobs exhaust brake.
Steve

Thank you, Steve. The reason I asked the question is because Joe Rhea's signature line says he has a c9 400, just like me.

[Dave Atherton]

Gentleman, think there is some misunderstanding about engine exhaust brake and the
engine compression brake. Want to point out Caterpillar 3126 up to Caterpillar C-9 will
have what is called engine exhaust brake (these above engines are called cast block engines
because they do not have replacement cylinder liners and cannot with stand higher cylinder
pressures). The Caterpillar C-10 and up to Caterpillar C-18 have replacement cylinder sleeves
That can with stand higher hp., higher cylinder pressures and are equipped with what is called
Compression brake or Jake brake. There is a very big difference in operation on Caterpillar
engines. The pac Brake is mounted on exhaust side of turbo charger and operates with a
Air cylinder opening and closing a flapper valve. With the compression brake,electrical
Solenoids are mounted under the valve cover on valve train which we talked not to long
ago. Dave Atherton Retired Cat Mechanic

[Joel Ashley]

As you can tell from Dave's description, a Pac-brake is an exhaust brake.  But many of us have one that looks just like, and is oft confused with, the Pac-brake brand, but is actually made by Jacobs Vehicle Systems, a company more commonly associated with the internal compression release brake called "Jake Brake".  Thus the confusion.  Chances are, Stan, yours is like ours - a Jacobs.  A close look at the unit, streetside top of engine via a bedroom access panel, should reveal the manufacturer's name on it.

Joel