Howdy Folks,

I don't have a ton of experience with working on vehicles, honestly I'm a total n00b, but I'm trying to learn. I've been crawling around on a bunch of different forums looking for an answer to this and I was hoping someone could help.

I recently bought a 1994 E350 Class C Motorhome. When I test drove the vehicle, it was a little loud, but I looked and saw the doghouse wasn't seated right, so I thought that was the problem. When I got home I took it off and found one of the hoses coming off the metal tube in this picture was burned through, both sides were actually burned through. I took the parts down to the local auto-store and they guessed they were probably something to do with the emissions system, but they wouldn't likely be able to get me hoses in those exact shapes. So I bought a length of hose and cut some. It was a bit awkward without the proper bends, but I was able to make something work. When I replaced the hose the engine got much quieter, so I figured I solved the exhaust leak and fixed it.

Wrong.

Turns out those hoses burned through as well, so I ordered some high temp hose and replaced them. As you can see from the picture, the high temp hose on the right burned through as well. The white powder is ash...

So in my crawling around on the internet trying to get an idea of WTF is going on, the only thing I can come up with is MAYBE the engine is running too rich causing it to run too hot. I'm not entirely sure what would cause that, but someone else mentioned maybe the O2 sensor was bad causing it to run rich? Does that seem plausible? The engine doesn't seem to overheat at all but something is clearly wrong.

Disregard the extra hose clamps on the hoses, it's a temporary solution to keep the hoses from kinking right there, please don't roast me. I ordered a repair manual so I can learn how to work on this stuff.

Too hot, burning through hose.


Concerned about the hose particulates blowing through the hose into this thing in the back. What is it? Emissions system sensor of some sort?

All those hose ashes are going into this

 

There is supposed to be an AIR pump on the engine. It is belt driven. Is it still on the engine?

Next,,,,,,your vehicle's emission system has what are called TAD (Thermal Air Divert) and TAB (Thermal Air Bypass) valves that are controlled by vacuum and electrical power from the vehicle computer based on engine temp info received.

That part with all the white powder on it is called a check valve and it needs to be replaced. It's purpose is to prevent exhaust gases from coming back up the line and burning the hoses that are bringing air from the AIR pump . Sometimes the pumps get destroyed because those check valves stop working.
.If that is the case it will need to be replaced.
Sometimes folks remove or disconnect the air pump because they don't understand why it is on there.
We should be able to assist you to get the system working correctly, if you choose to do that.
The parts tha you may need most likely will only be available from Ford, not sure.

 

Hi Hanky,

Thanks for that! I expect the air pump is still on the engine. I have ordered new check valves and am going to replace them both.

I checked into a new air pump, but the one I found online doesn't really look like the one that's on there. Would that be the Smog Air Pump identified in the back of the 3rd photo and center of the 4th photo?

This is the one I found online.

https://shop.advanceautoparts.com/p/...lVehicle=false

Thanks!

 

What I see in the 3rd and 4th photo are the TAB & TAD valves.

Pretty sure The AIR pump is driven by a thin belt off the crank pulley., it has been a while since I worked on them.
When the system is working right , you don't even know it is on there.

 

Ok, so Thermactor Air Diverter and Thermactor Air Bypass Valves...
Well, at least I have a name for those, unfortunately they seem difficult to obtain. No luck so far.
What do people do when they can't find replacements?

Can they be refurbished? Can parts from other models work?

 

It is not wise to go replacing good parts.
Until you check and verify they may not be working correctly, you most likely will not need to replace them..

Also , after you replace a good part and still have the same problem, not a good feeling .

 

Fair enough, the check valves arrive Friday, so I should know more this weekend.

 

One more thing... That check valve appears to be crimped on or something. Is there a special tool for that? Or maybe its a friction fit?

 

All the check valves that I had to replace had a male thread that the valve just screwed into the female part of the metal tubing..
When you receive the replacements , you will see how they are attached.

 

Looks like its a crimped connection. The hose connects to the input with a hose clamp, but the output appears to fit down into a copper pipe which has no threads, but does have some crimping on it.

Short of using a hammer to tap it out, I can't twist it or anything and there is nothing to get leverage on.

How the heck do I get this apart and re-assemble it??