Vacuum Pump hiss...

[dakotajeep]

Ok, forgive me if this is a stupid question! My vacuum pump hisses and blows air out the top through the openings while running. Is that normal? Also, my brakes seem to get hard after I pump them when the engine is cold. Is that a sign that he Vacuum pump is going out. I know that I need to test the vacuum to be sure but want to ask here before I go but the tester.

Thad

 

[1dieselman]

Sure sounds like its going bye bye to me, If you pull the vacuum line from the brake booster do you feel it trying to pull a vacuum there?

 

[fuzzy1626]

Sure sounds like its going bye bye to me, If you pull the vacuum line from the brake booster do you feel it trying to pull a vacuum there?

X2

 

[dakotajeep]

Ok, the hissing is most predominant at startup and then goes away once the engine gets warm......? Any thoughts? I think that I need to get a vacuum guage.

Thad

 

[1dieselman]

You may want to pull your belt and check the idler pulleys and vacuum pump pulley for loose bearings.

 

[dakotajeep]

They are all good.....I have a history of belt issues so they get checked frequently.....unfortunately.

Thad

 

[dakotajeep]

If anyone really cares (I also post help others down the road!):
I read my online repair manual and found some info.
I omitted to mention that my brake light also stays on while it hisses and the engine is warming. It just so happens that the low vacuum indicator is the Brake Light on the dash. Thats good to know if yours stays on when the parking brake isnt applied.

So I will be going to buy another vacuum pump tomorrow.

Thanks
Thad

 

[Truck#3]

i would check all the lines first to see if you have a vac. leak that could explain why there is hissing and poor brakes

 

[dakotajeep]

The hiss comes from the top of the vacuum pump. I got that tracked down pretty easily!!!!!

Thad