Last weekend went for a ride in the truck and it's not detonation but a loud rattling noise coming from under the truck. it usually only appears during light to moderate acceleration. I crawled around underneath suspecting a loose heat shield or something, but everything appears tight.
I then took a rubber mallet and beat on the exhaust. I could hear a slight rattling when I banged it close to the passenger side catalyst. Is it likely the catalyst media's came loose?
i had a garage do the same with my 2004 f150 4wd and it turened out to be the 4wd hub seal a quick test is put it in 4wd and if the noise stops then it is the vacum in the 4wd hub but it was the same thing garage told me at first was cat so i said why would it not do it in 4wd as well then and yes not using that garage any more
my boss has 04 harley f-150 4x4 his was on seal i am going to check my vacum on the lines first should be holding 20 lbs the new solenoid i picked up the updated one was 27 dollars cdn a quick test is put it in 4 wheel and if the grinding goes away it means it is either the solinoid or your seals wich are right behind your knuckles the solinoid is on the firewall right behind your battery with the two lines attached
I had same sound during accell only. All exhaust components were tight, but when under accell one of the heat shileds would come into contact with another part and the resonance (rattle) would appear.
The dealer fixed by welding heat shiled "up out of way" of contact area. This of course put undue stress on the exhaust and I developed a leak (just a week after rattle fix). Of course the dealer didn't admit that the cause was there welding the heat shield "up out of the way", but none the less the leak and rattle are still gone after a year and 10K-mi.
Can someone better explain the sound? I'm having a similar problem with my truck. On moderate acceleration I hear a rattling type sound that seems to be coming from the engine. It is hard to explain, but almost sounds like if you took BB's and put them in a thick metal pot and shook it. It's not very loud though, it's most noticable when you are driving along jersey walls b/c you can hear it echo off the wall. I only notice it when the windows are down.......