Glow plug warm up cycle?

[pojo4223]

About a week ago i noticed that when i turn the key to allow the glow plugs to cycle and warm up, theres this weird turbulence/pulsating noise that starts....? The truck starts up just fine and no difference in the performance. the noise goes away after the truck starts and thats the end of it. just curious what this might be? it is getting pretty cold at night and during some days here in Rhode Island, but i'm not sure if thats got anything to do with it? thanks for any advice in advance guys.

[Dirk]

My early 99 has always done that.

[pojo4223]

thanks for the input i appreciate it. Just a bump to see if anyone has any other ideas.

[Mikesf250]

Does it sound like a little pump. Because there is an electric vac pump under hood that sometime comes on when you turn on the key

[pojo4223]

slightly, but its constant lately until i start the truck after the warm up light goes off

[PSDfan99]

Yup I think its the vac. pump PJ. GUYYYYY!

[powerplant]

Vac pump mine seems to run more on start when the temp cools down.Its on the passenger side finder well.

[NCHornet]

Do your hubs still lock, or is the air blowing only out of the defrost vent? These are signs of a vacuum leak or pump problem.

[toddster]

hey nchornet, my 02 only blows out the defrost vent since my accident, I assumed a vacuum leak , where should I start?my heater box was changed by the repair shop and does not change possitions anymore (feet-face-only defrost)

thanks

[ridgerunner98570]

I would start by going back to the repair shop and telling the to finish the job.