Fixnstuff
Full Access Member
It sounds like something thwacking against the bottom of my bus.
Some of the comments have given good suggestions and advice but that is A LOT of stuff to try to remember and check.
1) As loud as that noise is, the problem is likely to be very obvious upon a visual 'hands on' inspection by someone who knows what they are looking at. (Hands on meaning that they are going to have to grab on to some components and forcefully try to move them by hand to find something that is loose and shouldn't be) and that could lead them directly to the problem..
In any case it should be quite obvious and should not take much time to locate it- just a routine inspection to find where the noise is coming from.
I really should stop at that so you don't get more confused, but actually you are learning a lot so I'll throw in a few more cents worth.
Transmission mount(s)/Engine mounts. As with some of the other parts you've seen, they are metal and rubber.
The rubber acts as a flexible cushion between the metal parts which allows for some movement when under use as he vehicle is being driven. The rubber can be considered as a vibration dampener as well and it serves that function in the motor/transmission mounts AND the easiest place to see this is in the carrier bearing which is approximately in he center of the drive shaft assembly between the transmission and rear differential (the 'pumpkin' shaped thing in the middle of the rear axle which contains the differential gears (ring gear and pinion gear) which produce the rear end gear ratio between the drive shaft and rear drive wheel(s) It is a set ratio but those internal gears can be changed from a lower gear ratio to a higher gear ratio. Low gear ratio is for pulling power such as in a construction pickup that needs to haul heavy equipment on a trailer (like a bull dozer or end loader) to a to a construction site. Low gear ratio will run higher engine RPM for a given speed (also depending upon the transmission) so they are not very fuel efficient at highway speeds. HIGH gear rations are for vehicles that don't need that low end low speed pulling power and at highway speed they run less engine RPM and are more fuel efficient.
A common LOW gear ratio in these vehicles is 4:10 and a common high gear ratio is 3:55. You'll see people mention those particular gear ratios in various topics.
I like to teach but I'll stop there. Some people don't like long posts which is a difficult to break habit with me.
AN ALIGNMENT SHOP COULD MOST LIKELY IDENTIFY THIS PROBLEM DURING A FREE PRE-ALLIGNMENT INSPECTION. I use Les Schwab Tire company because there are only a couple of choices in this little town. They have excellent equipment, really good warranties on the work they do and some free services like free tire rotations.... BUT THERE IS SOME OTHER ADVICE THAT YOU NEED TO KNOW and I'll give you that advice in a reply to david85 after I post this and make some coffee. and a couple of other quick chores (start a load of laundry and I forgot what else)
2) The noise is muffled in your video, it's muffled by the body and insulation of your bus and thus distorted quite a bit from inside of the bus. If someone knowledgeable had been outside on the curb or sidewalk as you drove by the noise would be clearer and probably much easier to identify. Is it possible to to get a video like that? OR if you had a way to attach a camera under the vehicle from somewhere like the middle (side) of the bus pointed forward that would do it. It's more the SOUND that would be helpful rather than the camera lens which by luck might be pointed at the actual problem.
BUT YOU KNOW WHAT? I am going to recommend this: DON'T EVEN DRIVE THAT BUS unless it is to an inspection or to have work done on it, or unless you really must drive it for other purposes and there are two reasons: #1 SAFETY, your own and for others on the road. Something could possibly break and affect the steering or brakes. Since we don't know what the problem is yet, it's better to play it safe. #2: and this is the far more likely scenario than a safety failure: When problems like this occur, they need to be diagnosed and fixed as soon as possible before this problem results in damage to OTHER parts which then becomes more expensive.
Like I've said, I don't think you need to worry because the problem will be easy to identify as soon as it is inspected. See my reply to david85 after it gets posted.
1991 Ford E350 7.3 IDI short bus. I am also getting a front end wobble. It's not a wheel bearing or stuck caliper. This is not constant, happens sporadically.