'02 intermittent front end knocking continued

ford
escape

#1

It’s been a year now since I first started to hear intermittent knocking from the front-end of my Escape. It’s finally getting to the point of some regularity/frequency. I was able to duplicate the sound for the mechanic but they are still unable to determine the issue.
So far I’ve had new struts, strut mounts and a left motor mount replaced in hopes that it would fix it. Also, things “secured down” a couple times. They’ve also ruled out CV joint, sway bar and stabilizer link.

Here’s more info about the knocking:

  • intermittent, but I hear it consistently when stepping on the accelerator after driving for a while (when engine is warmed up - like at the end of the day on my commute home), in hot weather, and seems to be more frequent after right hand turns. Speed bumps and the like do not trigger the noise.
  • Sound is coming from the middle to passenger side of front-end

It’s driving me mad trying to figure it out! I was able to record an audio/video of the noise too, wish I could attach it.


#2

Is there a loose exhaust hanger or cat heat shield in that area? That would be my number one suspect.

Another idea, a knocking sound that occurs during acceleration can be the engine pinging. Slight pinging can sound like a tapping on the top of an empty beer can with your fingernail. Severe pinging usually sounds like shaking a tin can full of nuts and bolts.

Attached audio files usually are not of much help. An experience mechanic would be able to rule the engine pinging idea in or out based on hearing what it sounded like during rapid acceleration. When were the spark plugs last changed? Is the gap correct? Overly-wide spark gap can cause pinging.


#3

Not sure about exhaust hanger or cat shield, so I’ll look into it. Spark plugs were last changed at it’s 100,000 mile service (about 2 yrs ago, current mileage is 119,000).
The sound is definitely a knock rather than a ping. Even though I hear it when stepping on the gas it doesn’t increase with speed. I’ll hear the same random (not at all rhythmic) knocking at 5 MPH as I do at 45 MPH.


#4

Concur, symptoms don’t sound liking engine knock or pinging. So that’s a good thing. Stabilizer link bushings are a very common cause of that type of symptom, but it sounds like that’s been ruled out already.

You need some more clues I think. You could try these ideas

  • Exhaust system inspection as noted above.
  • Warm the engine up so it makes that noise when you step on the accelerator. Note the speed. Go a little faster, lift off the accelerator completely and slow down through that same speed. Any noise then?
  • Same as a above, but this time shift into neutral and coast down through that same speed. Noise?
  • Same as above, in neutral, but this time apply the brakes to slow through that same speed. Noise?
  • W/car parked in driveway, use a length of garden hose as a stethoscope and rev the engine a little up and down while probing around with the garden hose to see if you can hear the noise and isolate the location where it is coming from. Careful of engine fans suddenly turning on, hot radiator, etc.
  • Try swapping the two front wheels left to right (temporarily only), see if the noise moves to the other side. While you’ve got the wheels off inspect the front brakes carefully for any small pebbles that have lodged in the workings.
  • Make sure it isn’t just something rattling around inside the passenger compartment or trunk. Remove everything not bolted down for a test drive. I had a golf ball get into a rear wheel well and that happened.

Did anything happen just before you noticed this? Hit a big pothole? Some work done?