Engine/Transmission (1994 - 1998) how much vacume??

[RAndrae]

On my 96 just wondering how much Vacume (on a guage ) I should be seeing. My pac exhaust brake is hanging up. Wont release when going down hill, if I slow way down or push in clutch it will release. I cleaned the air solenoid but it didnt help and it seems worse when engine is warmed up/hot. thx

 

[SheldonBates]

My '96 does not have an exhaust brake but with the original completely stock engine at 207,000 miles it always pulls a steady 21 to 24 inches of vacuum on the cab mounted vacuum gauge from idle on up. The 1996 factory service manual states in the brakes service section (Group 5-Page 11) that the diesel vacuum pump output "should hold steady in a range of approximately 8.5 to 25 inches at various engine speeds." There is a low vacuum switch that monitors booster vacuum level when the engine is running. If the vacuum falls below 8.5 inches the red brake warning lamp will illuminate.

Also, the altitude at which you are operating will have an influence on the reading. Highest reading will be at sea level. I live at about 900 ft. above sea level. A completely warmed engine will also sometimes have a little lower reading than when cold. Hope this helps a little.

 

[Missouri Mule]

Many years a there were threads about Pac Brakes hanging up. Seemed they were getting stuck in the brake mode. Seemed they had to clean piston. Also read they had to rebuild a component (sorry don't remember what it was).

 

[GAmes]

If your vacuum was low, the brake wouldn't engage. I recall a thread about cleaning one of the components also. Search is your friend.