Hi. My wife's Explorer (4.6, 4x4) has the loudest engine roar I have ever heard. It has been that way since the beginning and when in for service, was told that it was normal. It does not sound like anything is wrong, just loud. It reminds me of the sound you get when the fan clutch locks up. The fan clutch was changed last year nad it still roars. Any ideas?

 

I have the same set up. My engine sounds like a diesel until it shifts thru the gears. I have had two different Ford service managers ride w ith me and they say it is normal. My son has the Expedition with the Triton V8 and he doesn't have the same noise. Mine idles very smoothly but as soon as it starts accelerating the noise starts. Sort of like a spark knock but louder. I drove an 04 and it wasn't half as loud. It had 25K miles, mine has 47k.

 

Well, I looked back through the invoices and I was mistaken. I did not change the fan clutch last year. She was rear ended last year and was pushed into the truck ahead of her. Her bumper went below the truck's and the truck's bumper went through the grill. It pushed the radiator back into the fan and I assumed that they changed the fan clutch. I checked the Haynes manual and it states that the fan should spin freely when cold. Her's feels locked up all the time. So, tomorrow I am going to change the fan clutch. I'll let you know if it helps.

I also had a sound that sounds like your problem and I ignored it until the serpentine belt idler pully locked up and shredded the belt and the pully (left wife stranded). Dealer wanted $200 to replace and I did it with a flashlight in the dark in a parking lot for ~$60 in parts.

 

I have an 03 Eddie Bauer 4.6 and am currently on a mission to determine a similar noise in mine. Sound like one of yours is that loud fan noise some cars have and the other mentions a loud/knock/diesel sound. I have a noise that I would describe as on acceleration mine sounds like a very quiet diesel. It runs perfectly smooth, I just find the engine loud. I previously had an Explorer with the 5.0 and it was much quieter. The loudness has a slight knock to it like you hear when in a diesel. It's not loud like as a diesel but a knock that increases with RPM. I can also generate the knock if in gear with the brake on and feather the throttle up to about 1000rpm or so. The knock is noticeable as the rpm rises and not there as returning to idle. Yesterday I was driving around with everything off inside the truck so I could really listen to the noise at different speeds etc. The new thing I noticed was the knock/noise exists as I lightly accelerate through the gears (upshifts at around 2000rpm) until I'm in 4th gear (overdrive off) and then the torque converter locks and the rpm drops to about 1500. The noise seemed to diminish a lot at this point. I never hear the noise at highway speeds and I just assumed at that point you usually are getting more wind/road/tire noise so you just can hear it. Maybe it's the torque converter I'm thinking and when it locks its a solid coupling and the problem area is not in play. I'm having someone else take it for a ride today to listen. I'll see what they say.

 

Ray it sounds like I wrote your statements. Mine does the very same thing. Sure is annoying but Ford says it is OK. Made them document my complaint in case something happens later.

 

In an effort to eliminate "spark knock" (predetonation), have we tried running premium fuel in it?

 

Really don't think it is a spark knock. Sounds more like a "quiet diesel" engine.

 

I had a mechanic friend of mine listen and drive the truck this weekend. The conclusion is the knock/rattle is not the engine. He says it's either the torque converter or the input shaft on the transmission. The big clue was that the noise basically goes away after the torque converter locks up in either 4th or 5th gears. He was explaining that there are 2 shafts (one runs inside the other). One is the one that transfers the power when in lockup mode and one is when not locked up. If one is worn or loose this is probably whats causing the noise. He tells me that the 4.6L V8 combo is usually very quiet. So now all I have to do is convince the dealer to go digging in this area and get it fixed. I'll be posting the progress as if this fixes the problem I think a few others my be heading back to the dealer.

 

Replaced the fan clutch. that was the problem. It is amazing how much quieter the engine is under acceleration.

BTW - the Haynes manual has you drain the radiator so you can move the upper radiator hose out of the way. It is not required. I had the whole operation completed in 15 minutes. Props to Pep Boys - I was looking for the correct fan wrench to buy and was told that they have a free tool loaner program. So, I did not spend a dime on the tool. Even after I bought the fan clutch at Napa.