Help me with undercarriage anatomy?

Hey guys. I'm an idiot when it comes to cars and trucks. I watched a video on how to change my oil and that's about it. I have nobody to teach me about these things, but I still want to learn these things. I have a couple questions about the undercarriage.

First of all, The driveline (I think that's what it's called) had two parts. The rear end is almost spotless clean. While as the front part is really muddy. It almost looks like rust, but everything rubs right off. Is this a common thing or is the rear part new or what.

Also, right above the TCase, there is this line that comes from on top of it. And I'm not sure whether it should be connected to something or if I should just let it dangle there.

Lastly, I think part of the exhaust system is getting some rust. I checked and there's no holes, but should I save up some money and replace it? Or should it be fine?

Again, I don't really have anyone to teach me about mechanics of cars, so I really appreciate you guys takin the time to help me out, even if it's just a couple of miscellaneous parts in the undercarriage.

 

The driveline might be clean because it's getting wet from the road and washed off, otherwise I have no idea.

The exhaust part is your catalytic converter. The internals can corrode over time so if it's functioning properly don't mess with it, it's a necessary part of the car for emissions. It's very expensive to replace for oem, and the aftermarket ones that are cheaper don't last nearly as long. It's rusty because it gets so hot it will lose any protective finish on it.

Catalytic converters are basically designed like an oven to cook off unburned fuel gasses coming from your exhaust, quality ones are made of platinum components, that's why they're so expensive

Can't really comment on the hose, might be a breather tube or a vacuum hose, see how far it stretches and maybe there's a fitting you can find, maybe somebody else can chime in on that

 

Thank you! That really sheds lights on things.

 

The rubber hose is a breather for the transfer case.

 

That hose should continue up, and terminate in the engine compartment

 

Should I try to move it or do you think it'll be ok? Orrrrr...?

 

Assuming that is a short piece of rubber hose attached directly to the top of the front diff, then that is likely the 'breather' hose. It used to connect to the 'breather cap', before someone cut it. The breather hose and cap are designed to prevent water from getting into the front differential when driving through deep water (this is a GOOD thing).

You should re-establish that connection. I have attached a photo of the cap that it should be connected to. I took the photo looking directly down from above the brake master cylinder. The 'breather cap' is circled in yellow. This is on my 4-cylinder, so yours might be in a different location.

FYI, there is a similar cap attached directly to the driver-side of the rear diff. No hose there, however. Some guys modify this breather by using a rubber hose to extend it higher up. One of the many mods we 4-wheelers do.