I have a 1996 G10 van with approximately 143,000 miles. The van occasionally makes a very loud squealing or high-pitched groaning noise. One of the difficulties lies in the lack of predictability or consistency of the noise. It only occurs at low speeds. It seems to occur regardless of whether or not I am applying the brakes. It does not appear as if I have to necessarily be turning the steering wheel either. While the noise seems far more common in reverse, I believe it also occurs in drive. The noise seems to occur almost exclusively when I am either parking (even if it is just on the side of the street) or pulling out of a parking space. However, it does not occur all the time when performing these options.
The noise seems to occur far more frequently after the van has been driven for a while. For example, I do not usually hear it when I am leaving my house to go to work, nor leaving work to head home. However, I do hear it occasionally when I am parking at work (after having driven from my apartment), and, more frequently, when returning home.
This van is a relatively new purchase. I have had the rotors turned and front brakes replaced. I do not recall hearing the noise until after the brakes were replaced, though I could be mistaken. I lubed the chassis (as that was one of my initial guesses), but it did not resolve the issue. However, I certainly could have missed a fitting as this was my first time doing it. I had my sister take it to a shop. They did not notice a noise, but said the brake caliper was sticking slightly.
The noise is hard to describe. I suppose is less of squeal or squeak, and more of loud, but high-pitched groan. It does not appear to be coming from the engine or engine bay, but somewhere in the suspension or braking systems.