95 ford econoline van. there is a tube on the "side" rear of the engine that leads to the front. Into this tube are loosely placed smaller tubes coming from the engine (or maybe the manilfold?). This tube appears to have snapped. Would this lead to a loud exhaust sound?

Wheel disc warped and loose wheel bearing start with discs

blown head gasket

the tubes i think your talking about have to do with emissions that supply fresh air to the exhaust for those cylinders when required.if they break off you will get an exhaust noise which is what your hearing.there are only 2 ways to fix this.one is to repair/replace the damaged pipe or remove the pipes and plug the system off.be aware if you do the last it will fail an emissions test and have to be replaced to pass anyways.

1997 Ford Econoline Van Car Radio Wiring Diagram
Car Radio Battery Constant 12v+ Wire: Pink/Light Blue
Car Radio Accessory Switched 12v+ Wire: Yellow/Black
Car Radio Ground Wire: Black/Green
Car Radio Illumination Wire: Blue/Red
Car Stereo Dimmer Wire: N/A
Car Stereo Antenna Trigger Wire: N/A
Car Stereo Amp Trigger Wire: N/A
Car Stereo Amplifier Location: N/A
Car Audio Front Speakers Size: 6? x 8? Speakers
Car Audio Front Speakers Location: Doors
Left Front Speaker Positive Wire (+): Orange/Green
Left Front Speaker Negative Wire (-): Light Blue/White
Right Front Speaker Positive Wire (+): White/Light Green
Right Front Speaker Negative Wire (-): Dark Green/Orange
Car Audio Rear Speakers Size: 6? x 8? Speakers
Car Audio Rear Speakers Location: Side Panels
Left Rear Speaker Positive Wire (+): Gray/Light Blue
Left Rear Speaker Negative Wire (-): Tan/Yellow
Right Rear Speaker Positive Wire (+): Orange/Red
Right Rear Speaker Negative Wire (-): Brown/Pink

This info came from website: http://www.modifiedlife.com/1997-ford-econoline-van-car-radio-wiring-diagram/ ----I used this site for my 01 grand marquis, and it was accurate.

Sounds like you may have a loose connection somewhere...I would start by checking the negative battery cable as this seems to be the most common connection that is lost...follow the black lead down to where it connects...usually on the engine somewhere, and then remove it , clean the area where it goes with sandpaper or a wire brush and then reconnect...the positive cable goes to a solenoid that is triggered by the ignition switch..make sure these connections are tight also....the other lead on the side of the solenoid goes down to the starter..check and clean this also...hope this helps

follow the link to how to test the EEC 4 electronic control system this van uses, also known as OBD 1.
http://check-engine-light-codes.blogspot.com/2006/04/ford-1985-95-obd1-code-self-retrieval.html

they no longer use expansion valve.it has been replaced by a FIXED ORFICE TUBE

Yes it does have a heater core. Depending on options and series the core will be on passenger side behind the dash or under hood on passenger side. Just look for your heater hoses and follow them and they will lead you right to it. If you have any trouble let me know and I'll get info you need.

Under the engine, between the rear of the engine and the front of the transmission. It will be on a mount with an oil cooler, (it has metal fins) on the driver's side.

the blower motor in under the hood on the passenger side of the van. it has three screws that hold it in place and is ususally easy to change out