Groaning noise

1999 Honda Accord, 171K miles. Groaning noise that may last my whole drive. Next time I drive the noise is gone. It happens a couple of times a week. At a complete stand still, if I turn the wheel, I will get this deep groaning and the noise continues while I am driving. I have had the car checked by two different dealers and they cannot hear the noise nor can either find anything wrong with the car.

Is it more prone to happen if you are turning the steering wheel? Check the power steering fluid for level and condition.

Dealers checked the power steering fluid level.

It is really hard to fix a problem that goes away when you take it for repair. For Confirmation you need to have someone look at it while it displays the problem, but to me 2 guesses stand out, 1. Power steering pump, 2 loose belt, but pump is more likely.

I have thought all along it had to do with the steering. I will ask them to check this again. Thank you.