98 ford explorer noise on cold days?

If it makes the noise when you get to 6-8 mph, it is the abs pump is testing itself by priming. The abs system is designed to run the test once, in gear at 6-8 mph, if the system pressure is low. You might have an abs pump that is getting weak or noisy, or your brake lines could be vibrating against something.

Does your abs light come on for 5 seconds when you start the truck, then go out? if so, the system is working as designed.

If you can duplicate the noise on a slick surface, by slamming on the brakes from a slow speed (under 15mph), be sure to be safe, then it is working as designed.

Abs pumps usually aren't heard by most people, then they get freaked out when they do.

Abs pumps are designed to supply high pressures at a moments notice, so they test themselves.

Hope it helps......

If it has the 4.0L SOHC engine, it's probably a slight vacuum leak you are hearing. If that is the case, you'll need to have the rubber o-ring style gaskets replaced on the upper & lower plastic intake. How does the engine run when you hear this noise? Does it run silghtly rough? This particular is extremely sensitive to vacuum leaks. Also know that a slight whistling sound is a characteristic of engines equipped with plastic intake manifolds.

Slipping belt in cold or moist weather. Could be bad bearing on accessory in that area of engine.

Check under the hood near the windshield, there are probably leafs caught in the grill that sucks the air for the heater.

Check power steering fluid

Aiiii

take it to a garage

the whistle is a vacuam leak from your break booster