Strange noise only when on the gas pedal...

[jpoprock]

Everyone talks about chirping or rattle noises when accelerating... and some say it's only when cold or at certian RPM's. My noise sounds sorta like the idle of a diesel engine, happens warm or cold, at any RPM or speed, and goes away the second you take your foot off the gas pedal.

If I put the vehicle in Neutral and give it gas, no noise. If I coast in gear, no noise.

It's only present when I'm accelerating or holding a steady speed. No matter what speed. And I swear it sounds like a diesel engine idle, only not as loud. There is no way it's something "loose". It's not a "leak" either. It's definately related to whatever being on the gas pedal is mechanically doing to the engine.

So, when you step on the gas, what happens that doesn't happen when coasting in gear? Are the valves only moving when you're on the gas? Surely the tranny gears are moving whether you're holding a speed or coasting. I'm just sure this isn't "exhaust" because what would that have to do with only being on the gas pedal?

Keep in mind... my hubs are all shot. I know the roar of a bearing. This noise isn't that. And besides... a bearing spins all the time and the noise is pretty much present as long as it's spinning. This noise is ONLY when accelerating or holding a steady speed.

Please help! I've read countless threads that lead to nowhere or aren't the same thing. And I know this can't be unusal. There is no way for me to check for the noise unless somehow I'm able to strap myself under the vehicle as someone drives it down the highway! LOL.

Thanks all!

Jason

 

[Number4]

Don't have the answer, just suggesting you mention the engine size.

 

[jpoprock]

Sorry, thought it was in my info. Guess not! 2002 Explorer Limited 4.0L SOHC. Or is it 4.6? Crap. I don't remember. It's a 6cyl and not Flexfuel.

Yeah... I'm no help...

 

[Number4]

If it's a V6, then it's the 4.0.

Sounds drive train related as it doesn't happen in neutral.
Might have a trans shop scan it for codes.

 

[jpoprock]

Ok, I'll sched a service. I'm hoping with a tranny that it doesn't always involve a huge cost. And it's likely not something I can do myself.

 

[jpoprock]

I know what the problem is. It's the differential. It's leaking oil where the driveshaft connects. I've had new spiders installed once before, and I think Ford put a new diff in it at about 25k under warranty. So I'm hoping to find an honest shop who can replace what's needed and not automatically say that I need a new differential. Because I just don't think that's the case.

The reason I am sure it's the differential is because the noise only happens when the driveshaft is spinning. I put the vehicle in neutral and coast, I am only hearing a slight roar which I know is my rear hub. The majority of the noise is the differential. Once I get that fixed I will then address the hubs.

I'm just glad it's not the transmission! My transmission shifts just fine and I'm not getting any error codes.

I will report back with follow up!

Jason

 

[Nuke'em]

Hey Jason!

I'm curious to see what you find out. I have a similar sound coming from under my hood as well. Same thing; noise only comes in while I'm accelerating from a stop AND also when I'm accelerating from a constant speed.

It sounds like a faint whistle, much like your "idle diesel engine" description you mentioned earlier.

I was hoping it wasn't the tranny but I too have great tranny shifts with no jerking...so I "somewhat" ruled out the tranny. But the differential would make sense.

Please keep us posted. This is one of two issues that I'm trying to troubleshoot on my '03.

-Mike