Air can make power steering system howl

Q I have a 2001 Silverado 2500HD with a 6.0-liter V8. The power steering works just fine, but it "howls" or whines all the time. The noise changes with RPM; the pitch goes higher. I do not have to be moving or turning the steering wheel to hear it.

I was told to "bleed" the system by turning stop to stop 12 times. That didn't make a difference. Do I need a new pump? Should I try to drain the fluid with a turkey baster? Use Trans Tune?

A First, make sure the power steering system isn't low on fluid. In many cases, a whining noise from the power steering pump is because of a low fluid level allowing air to be mixed in. This creates a foamy, aerated fluid that is somewhat compressible -- pure power steering fluid is not -- and generates the whining in the pump.

If the fluid level is up, I'd try adding 2 ounces of SeaFoam Trans Tune to remove moisture and "condition" the fluid. If this doesn't quiet the pump, a complete flush and refill of the power steering system with new fluid is worth a try.

As long as the system generates proper hydraulic pressure and functions correctly, you can live with the noise. If the whining eventually leads to inconsistency in or loss of the power assist, it may be time for a new pump.

Q I have a '96 Ford Explorer with about 100,000 miles on it. The vehicle is in good condition for its age and it runs well, but because this is my second vehicle, it gets little use.

Unfortunately, the blend door on the heater is stuck on the hottest setting, which is fine during the winter but is going to be a problem this spring and summer. I've been able to confirm that the motor that moves the blend door is working, but somehow the door has become disconnected from the motor.

The dealer indicates that this is a $1,000-plus repair, a huge expense considering the value of the truck. Would it be safe to separate the coolant lines from the heater core and create a loop for hot coolant to bypass the heater core? I'd keep the heater core full of antifreeze and seal the input and output lines. By doing that, no hot coolant would be able to enter the heater core, and the heater could blow only ambient temperature air or air cooled by the air conditioner, which still works great.

I'd do this for the summer, then reconnect the coolant lines to the heater core next winter when I need heat again. Would this bypass of the heater core create any safety or performance issues with the engine or with the air conditioning system on this vehicle?

A Not that I can think of. This is an entirely practical fix for your older truck. By creating a complete coolant circuit that simply bypasses the heater core, I think the engine and its cooling system will be happy. And keeping the heater core full of coolant during the summer should prevent any corrosion or sediment from forming in the core itself.

The only potential performance issue I can think of is that the air-conditioning performance may be somewhat compromised. However, if the blend door is stuck in a position that allows no outside air into the heater/evaporator housing, it shouldn't affect the A/C performance.

While I like the practicality and simplicity of your fix, before doing so I'd suggest calling the folks at Dealer Automotive Services in Hopkins and Roseville and ask them two questions. First, will your fix work satisfactorily? And second, is there an easier way to repair the stuck blend door?

Q I have a 2002 Ford F-150 with 130,000 miles. As the song goes, I love my truck. I had my oil changed yesterday, and the service tech said my transfer case was full. I'm not sure what he meant but it sounded like it could be a problem. He could not give me much more information as to what was wrong nor what I should do. Do I have a problem, and if I do, what is my course of action?

A Am I missing something here? The transfer case should be "full" -- full of the proper lubricant. If the tech checked the lube and found it full, all is good. If he found it full of water or something other than the proper lubricant -- Mercon automatic transmission fluid -- then you've got a problem. But this seems unlikely.

Your best bet is to have another shop check the fluid level and confirm that the transfer case is full of the proper lubricant. And from my perspective, changing the transfer case lube -- along with the transmission and differentials -- every 30,000 to 50,000 miles is good maintenance.