When its about 50 degrees or colder out, just after I start the truck, if I depress the brake pedal I hear a growling/grinding noise. It will stop 15 minutes or so after I start driving. I do hear the noise also after starting the truck without depressing the brake pedal but at a much lower level. I am assuming it the hydroboost but could use some advice on how to troubleshoot.

the noise happens while the truck is not moving (not the brakes pads making the sound))

 

check the power steering fluid level

 

If the truck is is having the problem in cold temperatures I recommend changing out the power steering fluid. If you've never changed out out ps fluid it is a good idea to flush it out & replace it with synthetic ps fluid like Royal Purple. It will get worse in the winter time if you don't change it.

 

guaranteed it's the power steering pump/brake booster.

i had the same problem, flushed and replaced with synthetic many many miles ago and have fine ever since in regards to this issue . . .

 

Good luck finding Synthetic PS fluid. Perhaps it is sold more in the extreme North.

But yea, it is your PS pump.

 

i have seen royal purple at autozones and a few others brands tha are synthetic. goo luck i just replaced my PS pump after a piece of the gear snapped off and locked up the pump, that noise was happening in cold weather sometime before that.

 

how much fluid does the PS take?

 

takes approx 8oz in the resivoir, so if you do the turkey baster thing to suck it empty you will get about 4 "flushes" out of a liter.
so suck it out fill back up, DRIVE truck for one hour or so and do it again and again, until you used up the 1 liter. I suck mine out(8oz only) and refill every 6months.
PS fluid is most neglected on any veh and PS fluid in a dodge is seeing double duty!

 

Suck some fluid out and if it looks clean add a bottle of LubeGard power steering treatment.
I've found it just as good as synthetic.
It's sold at most autoparts stores.