VACUMN PUMP

[99BEIGEPOWERSTROKE]

I had a problem with my heat not blowing out of vents but it started working again. The problem is my vacumn pump seems to run non stop. Its really loud when I am letting my glow plugs cycle before starting the truck. Is the pump bad since its loud and runs all the time? I have heard another truck and when glow plugs are cycling on it the vacumn pump isnt loud.

[cvdenson]

I have the same problem. Nothing blows out the vents on any setting.

[NCHornet]

Look for a loose vacuum line in the passenger footwell. No a vacuum pump should not run constantly, otherwise no vacuum is being created. The other common spot is on the back of the front hubs ( 4x4) the vacuum line just slips over a nipple and that's it. The hose gets cracked and splits and you loose vacuum, cut off the damaged section and replace over nipple. I check these during every oil change. The pump will run for awhile as it does take a minute or so to build vacuum in a large system. But check those three locations, if they all look good start back tracking towards the pump. I have found vacuum lines melted on the manifold, but it was a rare bird.

NCH

[99BEIGEPOWERSTROKE]

I know have heat blowing out of vents though and the pump still runs all the time. Is there any other reason it would run all the time and be so loud?

[JSchuricht]

When I first got my truck, the pump was running constantly. After it quit running, I found a line that a rodent had chewed through. Vents were still working properly, but the hubs weren't locking. Patched the line and the new pump cycles properly.