First off I have a 93 bronco with 302. Inside the motor compartment between the fire wall and the motor there is approx. 5/8" black hose connected to (it kind of looks like a fuel filter, but not). Well it's just hanging there has one hose coming in and no hose one the other side. I'm kind of thinking this should be connected to something. Is there supposed to be something hanging there between the firewall and the motor or is something disconnected? Also it does make noise sometimes, after it's warmed up and idleing, then it goes away as soon as I hit the gas. I know this sounds crazy, but I can't seem to figure out what the hell it is and where it's supposed to be and it's driving me nuts.

Thanks
John

 

can you post a pic of it. Im not sure what it is but if I could see it maybe I can help

 

Where exactly is it "hanging"? Which side of the engine bay? near the front? rear?

 

where at the back of the engine.......like toward the left or right side of the fire wall? Is it a rubber or plastic hose? We really need a better description of the item and the exact area it lives in.....a picture would be best.


I also have a 93 w/302.....if you like look through my pics and point out the part from there. You can access my pics with the link in my signature at the bottom of this post.

 

Thanks for the replies guys, it's hard to get a pic of the thing it's hanging in a wierd place, but I'll try.

the part itself is similar to a fuel filter, but it's more of a pancake shape. It's hanging between the motor block and the fire wall more towards the passenger side of the vehicle. When I say it looks like a fuel filter I mean it has a inlet side and exit side like a fuel filter, the inlet/outlets are more like 1/2" though. It's made from the same material (it looks like) as a metal fuel filter. You really can't see it from the top, but if you look from under the vehicle you can kind of see it. I don't have the vehicle right now (I have to keep it at my moms place, I don't have room). I will try and get more info when I get a chance to get over there.
Thanks again
John

 

Sounds like its a Thermactor check valve that has seperated. There are two on your 93. The one in question is probably supposed to be attached at the bottom to a metal tub that runs into the catalytic converter.

 

Greystreak,
Would the thermactor check valve make noise ( kind of like sucking or blowing) when disconnected? Also what does it do, would it harm performance?

Thanks for the info.
John

 

I had the metal corrode clean off my thermactor control valve. It broke the tube off the metal. It also caused my check engine light to turn on. They can make a whining noise sometimes. It looked like it would have been a pain to get to so I let it go for a while, then about a month later I toasted my engine. So needless to say when I took the engine out I replaced the valve.

 

Ya thats not good, Mine seems in good shape I just had the motor remanufactured and now I wonder if they didn't hook it back up. I looked around to see if I could see any loose hoses that belong to it, but I didn't see anything. It is in a really hard to get to spot, and now that you say that it is kind of a whining noise. So anyhow what the heck does the thing do?

 

Yes, there is a flow of fresh air through it and at idle the air flow is lower simply because the air pump is running slower. Its very probable that you will be able to hear the air flow and hear changes in it as engine rpm's change with the valve separated from its proper connections. The check valve keeps hot exhaust gasses from backing up into the Thermactor air injection plumbing and burning up or melting down the rubber hoses that make up the system. Loss of fresh air flow into the catalytic converter will not necessarily harm your performance but it will screw with your emissions possibly enough to fail the truck during a test. If the check valve has broken off the tubing there is nothing keeping the hot exhaust gasses from running back up the metal tube into the engine bay or up between the engine and firewall. This would be the primary concern in this situation.

 

OK I finally got too spend some time with my Bronco and my manual and I do beleive it has something to do with the thermactor valve. There are two hoses going in each side of the thermactor valve and one coming out the bottom. The hose coming out the bottom of the thermactor valve has a small filter looking thing attached, this is were its hanging. I couldn't find were it supposed to go. any Ideas?

 

Ok, the setup, starting at the Thermactor tubing that runs along side the passenger side exhaust manifold, goes like this. Metal tubing along the manifold to a formed rubber hose into the diverter valve. The diverter valve has two more larger diameter (5/8" I.D. approx.) hoses coming from it and two vacuum lines. One large hose runs to a check valve at the back of the engine that is mounted on a metal tube that runs between the cylinder heads. The other large hose runs DOWN to another check valve that is clamped to a metal tube protruding from the catalytic converter. (This one is usually easier to see from UNDER the truck). My best guess is that the one that should be attached to the CAT has separated from the tube on the CAT. If all else fails the diagram of the Thermactor plumbing SHOULD be part of the underhood decal marked clearly with the word CATALYST.