Hi Everyone,

I have a 1996 3500 133k. My ABS and Brake light are coming on intermittently, also when the lights are on, I have no cruise control.

After reading on here, It appears I am having some sort of vacuum issue. I am not at home, and have about 1200 more miles to go on this trip. I am going to head to an auto parts store in a bit, to find a vacuum tester, so I can test for leaks in the system. The system doesn't appear to be holding any vacuum, after running the engine for a while I pulled one of the line off that 4 way connector and "did not" hear any whoosh of air. With the engine running if I pull off the same line, I can hear a "hisssss" so sounds like it's trying...

My brakes seem to work fine, haven't noticed any stiffness in them. Also when I change the heater controls, they all seem to work and move air out the indicated vents...

My main question is; what else is affected by this? I can make it home without cruise control, but I don't want to do any inadvertent damage if possible.

 

Update

Ok well, I bought a vacuum tester and tested the lines, no leaks...

I decided that I would take it to a dealer that was near the hotel I stayed at. They said it was the anti-lock brake sensor that needed to be replaced. They happened to have one in stock, so a few hours later I am on the road. After a day of driving, no intermittent ABS or Brake light, and cruise works like a champ...

Chalk one up to the dealer, treated fair, solved the problem, and "the big wow" in and out the door in less than 2 hours.

My original question remains though; what potential damage can you do to your truck by running with no or diminished vacuum?

Thanks

 

The biggest problem is a vacuum leak can cause increased blowby and oil usage.
The vacuum pump is basically a compressor with the pressure side discharging into the crankcase. If there are no vacuum leaks, no discharge to pressurize your crankcase.

 

Right, but that wouldn't be causing any real dammage unless you let it run short of oil correct?

 

My 2nd Gen vacuum leaks were at the transfer case. There are 4 vacuum lines that plug into the top of the transfer case. This controls the vacuum actuator on the front axle. I ended up putting new (tight) vacuum lines at the transfer case. Then used vacuum extensions to tie into the original lines. At every vacuum connection throughout the engine compartment I added small zipties. This cured all vacuum related problems.