I have a 97 f150 4x4 - new body style - with the 4.6 that I bought about a month ago. about 2 weeks ago, I started hearing a noise that at first I thought was spark knock. But, two days ago while driving with the windows down, I heard that it was coming from the middle of the truck rather than the engine compartment - and it's most prominent when I'm accelerating. Is anyone familiar with this?

Thanks and feel free to email me,

 

Does the sound get faster the faster you go?

 

yes it does now that it's gotten worse. I took it to a shop here in Greencastle, IN and when they put it on jackstands and ran it in gear, it's clearly a bearing going out. They're going to pull the transfer case and open it to ensure that there's no other damage and go from there for the reman. Lucky me!

 

I know it's difficult, but can you describe what "spark knock" sounds like?

I've noticed a noise when accelerating...thought it was just another noise in the FIPK but just hadn't noticed it before. It has me a bit concerned.

Any ideas always greatly appreciated

 

Umm.........there is an engine forum. Might get more help there than jumping in on an unrelated thread.



As far as the noise in your drivetrain goes you might wanna have the shop check the condition of your ujoints if they haven't already. I did mine recently after 75k. But the noise I was having sounds similar to yours.

 

Well, it's now in the shop and the problem is definitely in the transfer case. My hope is that it's just the chain. I was told that when the chain wears/stretches that it can give such a noise - I know that regular chains/sprockets can. Anyway, they're banking on a bearing or the chain being bad, though I'll have them do a complete reman. regardless - unless the case is messed up inside. They put it up on jackstands and checked it out while the motor was running and with it in gear and that was definitely the source.