2002 Ford F150 V8 Four Wheel Drive Automatic 89000 miles
My truck has a knocking/bearing noise coming from the engine compartment that does not get louder when you rev up the engine. SOmetimes it goes away after it warms up, but there is a whooshing sound coming from under the dashboard that comes and goes. It almost sounds like the AC compressor unloading. The AC has not worked in a while. I had the idler pulley replaced and the noise went away for about a day, but came back. When you start it cold, sometimes it makes the noise and sometimes it doesn't. I have the oil changed every 3000-4500 milles faithfully, and don't beat the truck. Is it possible the Ac compressor could be making this noise? I have been told it would cost thousands to repair because they have to pull the cab to get the engine out. I have held the brakes on and rev'd the engine, and I do not hear any knocking, nor do I when pulling a hill.
The noise you hear underneath the dash is the heater core.
January, 20, 2008 AT 5:52 PM
If it's what I think it is, your noise is refered to as " piston slap.&Quot; If it is piston slap, Ford says it's normal. They also say it does not affect engine life. I worked for Ford for years, but I don't entirely agree. I have heard it on a lot of vehicles. It does sound like a rod bearing out. One way to ease your mind would be to have an oil pressure test done on the engine. If you have lower oil pressure, it may be bearings, but if not, it's piston slap. Give a shout if you have any further questions.