Engine/Transmission (1998.5 - 2002) Exhaust Brake Back Pressure

[SWC]

I have a 2001 ETH with a Pac exhaust brake. What is the back pressure that is safe when the brake is engaged at higher RPM? I want to put a gauge in the cab to monitor the pressure under working conditions.

I had the original brake replaced under warranty. The new brake is not as effective as the old one. The back pressure at idle is around 16 psi. Is there any way to adjust the brake for more back pressure?

Stan

 

[Sticks]

I want to say the max back pressure you can safely get away with is 35psi, after that you stand a real good chance of floating an exhaust valve, in which case you will need to get stronger valve springs.



I have no idea how to adjust them. Do a search, or find the pac brake website for operator instructions.

 

[JFinke]

On the 12V pac brakes you have to install a plug in one of the 2 holes in the butterfly valve IF you put in heavier exhaust valves. The 24V motors have heavy spings that allow full braking from the factory. My 24V brake doesn't have the second hole, but the one we put in a friends did. We added the supplied plug. All the 12V brakes are supposed to have the second hole left open unless you do the valve spring upgrade. Maybe you got a 12V style without the plug installed.

 

[24VChev]

Back PSI

I think you can go up to 60 PSI safely with the 24V. Should be 20-25 psi at and idle with everything hot. Sounds like you may have both the holes open on the butter fly valve as suggested by JFinke. Make sure the valve is closing fully





Malcolm

 

[Steve Campbell]

I installed a "T" when I put in my thermocouple.....

and hooked up a guage just to see what I was doing.



54-55lbs back pressure at 2400+ rpms.



60 psi is the valve spring pressure on a 24 valve (and the 12 valves can be upgraded), so anything under that should be OK.

 

[SWC]

Thanks for the replies. The butterfly on my brake has one hole. It is slightly larger than the hole in the first brake. I took the pin out on the clevis on the ram and moved the valve by hand to see if the valve was not positioned properly. That made no difference. One of the Piers guys sent me the screw for the 12 valve, but I did not want to install that until I knew what the back pressure should be.

Thanks again. I knew I could get the information I needed from someone on TDR!

Stan