Pac Brake acting funny

[Cowboy Medic]

I am having a strange problem with my PacBrake. It is not activating all the time and when it does it will feel like it is turning on and off. I have noticed it most right at around 1500 rpms. I am not sure what the correlation would be but it is the only constant I have identified so far. Perhaps someone could explain the system to me again and give me some ideas on what I should be looking for. I am hoping to have time tomorrow or Saturday to start digging around and looking. I am suspicious of a leak in the vacuum line or something along those lines but I could be way off base. Anyone out there with some ideas please shoot them my way. Only thing I know for sure is it is not the typical problem of it sticking because it moves fine just cuts in and out at the rpm range I mentioned. I do know that my led indicators are constant even when the brake itself is cutting in and out, I am comfortable going through the electrical side of it and checking for any shorts etc. Just want to try and get it back to running smoot like I have been used to.



Thanks in advance for whatever you can offer.



Jon

 

[Reb.B]

pac brake makes a pretty good brake but u constanly have to lubricate them. Need to spray WD 40 or LPS 1, or to really make it work right need to find some PB blaster, something like that. Spray the shaft on the brake and have somebody turn it off and on. Also spray the little brass filter on the controller. If that isn't it make sure u have a good pos. and neg. lead to the unit and that there is no vacuum leaks. ooo, one more thing to check. The lines that run from the brake to the controller can get cracked by too muck heat from the exhaust manifold. U can get a vacuum leak there too. Good luck

 

[DieselB59]

If you suspect having a vacuum problem, see if your dash vents switch to defroster only when the problem is happening. If you can, get a vacuum tester and gauge and see if you're not having a low vacuum problem at low RPMs. Furthermore, check vacuum at the pump with nothing else other than the vacuum gauge directly hooked up to it. If your vacuum is poor with nothing hooked up to the pump but a gauge, then your vacuum pump is weak. They don't fail like the old Ford ones do, but if it can work, I promise you it can surely fail. As far as lubricating the Pac Brake, make it a part of your regular service, but you don't have to constantly lubricate them. Just using them on a regular everyday basis will prevent any problem with the shaft.