Hello, My name is TopoGeorge. People call me TG and this is my first post. About a year ago I bought a 2005 Excursion mainly to haul a 12 foot enclosed trailer, a small crew of people, and sometimes a 24 foot TT across the country. I sell books at school conventions every spring and summer. I also have a 2001 E350 extended that I use for the bigger shows. Both vehicles have the V10 and I am very satisfied with the performance. Shortly after I got the X I noticed a "thump" type noise right at the moment of acceleration and just before coming to a complete stop. So I went to the internet to search out an answer to this mystery. I was hoping that it wasn't the transmission. That's when I found this awesome website/forum. I spent the next three or four days reading almost every post and thread for the X. I found the solution to the the "thump" problem ( transmission tail shaft spline lubrication, which by the way may need to be done again because the noise is back! ) I can now unlock my doors from the keypad and because of this forum, almost ready to install OEM fog lights. But I now have another mystery that I have not found a solution as of yet, hence my first posting.

Here is my mystery! This winter when I first start the X I hear a "bump" or "thump" noise that sounds like it is coming from under the rear of the vehicle. I can be moving or just sitting there when I hear this "thump". Only one "thump" sound and only after the vehicle has set over night. This noise occurs within the first 30 seconds after start up. The first time I heard the noise I thought I had hit the trash can at the end of the driveway. The other bit of information is that the noise does not occur every time. Another way of describing the noise is this: I remember when my buddies and I got our first cars and would hang out together. We would play tricks on each other. As a friend would leave and back his truck out of the drive we would stand next to the vehicle and use our fist to "thump" the side of the truck to make the driver think that he hit something. That was fun for a while. The noise I have has the same sound. Maybe this is payback from my past? Anyway, if anyone has any ideas on what this could be I'm open to suggestions.

 

It's not your imagination, I've heard it too. You start 'er up, and within a couple of seconds something goes, "bang". Sounds kind of like metal on metal.

When I park my X, I back into the garage. I've begun to think it might be the ball joints, when going backwards the loading is different than going forward, when you stop they are in a weird positions, and when they get a chance to unload, 'pop'. With all the discussion about needing to change ball joints regularly, and other symtoms relating to ball joints, that's the direction I'm leaning...

I'll be paying attention to this thread.

Archie

 

I have the same noise. Imagine holding a bowling ball about 6 feet over a metal file cabinet, and then dropping the
ball on the file cabinet. That's what my noise sounds like. The noise is quite loud and you can feel the vibration of it.

It is definitely something in the engine compartment.

 

what it sounds like to me is just some type of expansion caused by the heating of the exhaust... but that is just a quess... i would start by looking at heat guards or something real close to the exhaust...
wrap duct tape around the heat guards and see if the sound changes or goes away

 

VA
that sounds a lot more intense than he is describing... quite possibility two different things...


VA i got my 1:43... did yours ever show up...

 

Ball joints and suspension bushings.
Ball joints and suspension bushings.
Calipers calipers calipers calipers.
Replace these and your noises will go away.
Repeat as necessary.

 

That's weird. I've only had mine for a short time and just last night noticed a strange noise on start up. Only lasted a split second. Kind of hard to describe. I was stationary on the driveway, when I turned it off and started again nothing unusual. I thought I might have been hearing something, sounded like it came from the engine compartment though.

 

I've had 2 different SD and they both did that. If you will notice the next time it happens look down and see if you left the AC on, (remember that the defroster uses the compressor), if you left it on the culprit is the condensor. You have what is essentially a small explosion in there (with no fire just liquid to gas explosion). It is really nothing to worry about, just scares the BEGEEBERS outa me everytime it happens.

 

I believe the sound you are hearing is from the blend-door assy. Its in the heater box.
This is controlled by vacume and will pop closed upon start up once vacume comes to pressure in the door motor assy.
My EX does this too and I had my wife start the truck while I listened on passenger side floor area. Pop right there. You can feel the vibration with your hand on the heater box.

 

My vote is also for blend door.

They all do it, whether you hear it (or feel it) or not.

Pop

 

I had a service tech in my truck to track down the mystery sound....it is the blend door.

 

I have same noise,will verify tomorrow.thanks for help.

 

Yes it comes from that spot but I guess we can't do enything about it???

 

Watching this post to find a fix.

 

I have the same noise, the blend door.