I have a knocking sound coming from the underneath of the truck. It doesn't sound like it is coming from the engine and when I rev or drive the truck you can't hear it. It is knocking when it slows down to idle and is very noticeable when standing next to the truck. Any ideas of what it could be?

__________________
1999 Ford Ranger, 5 Speed Manual Overdrive

Can think if prolly 20 different things, checked oil lately? Checked u-joints, checked tranny fluid, is heater or a/c on when u hear it, clutch related components?

Sent from my iPhone using FRF App.

__________________
2005 Ford Ranger XLT Extended Cab, 4.0L. 245 Cu. In, 5-Speed, 4.10's, KYB'S @ corners, Moog Hubs, Rain Guards, and Mobil 1 for life.

As a matter of the fact and assuming that you have looked for and found nothing obvious, and that you happen to have a 4.0 (OP doesn't tell what engine it has) then yes, I have a very good idea what you are experiencing.



4.0 OHV MARBLE NOISE

Some 1998-2000 Ranger/Explorer equipped with a 4.0L OHV engine may exhibit an engine noise that may be perceived by the customer as a "Diesel" type noise and is known as Marble Noise. Marble Noise is clearly heard when the vehicle is at idle, under 2000 RPM or under very light/no load. High mileage studies of the condition show no adverse effect to engine life or performance. Cleaning carbon from the combustion chamber will have no effect on the Marble Noise condition. Marble Noise is a characteristic noise of this engine and cannot be serviced with an engine exchange.

__________________
2004 Ranger FX4 Level II, 5R55E, Sonic Blue Pearl

Proudly JAP/RICE free since March 2000