I need help in identifying a hose on a 91 Ford Ranger 4.0L, V6. Sorry I can't get a picture. I can't reach the area very well. Its a ribbed hose about the size of a radiator hose, coming from the engine block, almost under the battery tray (passenger side). It goes toward the grill of the truck. It doesn't appear to hold any liquids since its cracked to hell. I was thinking it was some kind of air intake or vent. Any thoughts?

 

Welcome to the forum

What you are describing reads like the air pre-heater hose, looks like this kind of hose: https://contentinfo.autozone.com/zne...96024/image/2/

Flexible and ribbed like dryer vent hose but metallic

All Fuel injected Rangers have a Cold Air Intake(CAI), there is a tube from Rad support to Air Cleaner box, it pulls air in from behind the grill, gives engine better power

On this tube is a vacuum valve that diverts air flow from Cold Air to pre-heated air, this is where the flex tube is connected


Since at least the 1940s car makers have added air pre-heaters to engines so they could warm up faster
A thin metal housing was installed over/around an exhaust manifold forming an "air chamber", this air would be heated up very fast once engine started
A diverter valve would pull this warmer air in to the carburetor which prevented icing in very cold climates but also warmed up engine a few minutes faster, so faster heat inside the car and better engine performance/less choke
The diverter vacuum valve is controlled by a bi-metal vacuum valve, these require no power, the bi-metal valve opens and closes based on temperature inside the air cleaner, so when cold the bi-metal valve passes vacuum to diverter which moves to pull in the pre-heated air from around the exhaust manifold
As the air in the air filter box warms up the bi-metal valve closes bit by bit until no vacuum is going to diverter valve and engine is warmed up

Same thing is used on fuel injected engines, for the same reason, although faster warm up also lowers Emissions, so these pre-heaters are now considered an "emissions system" and required to be working in states that have Smog testing

You can buy the metallic tubing by the foot, and there are different diameters, so you need to measure what you have now

These pre-heater tubes and "air chambers" are often removed during engine work and then never re-installed
Unless you live in a cold climate or need Smog testing, you would never miss it not being there

 

Thank you so much. That is exactly the hose I had the question about. I'm glad you said that it doesn't have to be replaced because it looked pretty hard to get to. I don't need something like that so I'll just leave it alone.