Hey everyone, new to the site. I just picked up a 95 F150 2wd with a 302 EFI...I have been hearing a loud rattling/ticking noise after the engine warms up but only at 2,500rpm's or so and lower. I got underneath the truck last night and found what it was. The truck has true dual exhaust with no converters so whoever did the exhaust left the air tube just sitting there hooked to nothing. That is definetley the source of the noise I have been hearing...my question is what is the best method for fixing this? The smog pump obviously isn't needed as there is no converter(s) on the truck so should I get a short belt and bypass the pump? If I do this then what hose(s) to I need to plug or remove, or can I just leave everything where it is? Any advice appreciated....

 

You can leave it the way it is and it wont hurt anything, it will just be noisy. I'm not sure if you can just bypass the pump with a shorter belt because of the way the pullies are routed, but i know that Ford Racing sells an air pump eliminator kit which is a idler pulley that bolts on in place of the air pump.

-Jon

 

I would just leave it the way it is, but that noise is awful to listen to. Maybe I could just attach something to the end of that hose to muffle the sound...

I think I can bypass the smog with a shorter belt, I am just unsure of what components to remove, or hoses/lines to block off without making the computer throw a code.

 

I thought about just plugging/crimping the hose, but I didn't know what effects that would have on the system...

 

OK...one more idea: I was just out running the truck in the driveway and thought of something: When the truck is cold, no air comes out of the hose, but when it warms up, something re-directs the air from what I am assuming is the heads to the exhaust. Could I somehow override this so it is always pumping air to the heads?

 

Sorry about all this rambling...

I found the relay that must control the valve that directs the air from the heads to the exhaust and I unplugged it. That stopped my noise and the air from coming out of the exhaust air tube. I will assume that this will re-direct the air to constantly flow into the heads. Any problems with running like this? There was a second relay next to this one I unplugged that didn't seem to do anything when I unplugged it.

 

I'm presuming you live in an area that won't see any emission testing any time soon.

There are a couple different systems you might have, so this will be fairly general, and probably confusing, so I apologize in advance: Follow the hose from the smog pump until you come to a valve with another hose outlet of the same size, and one or two vacuum hoses. If there is only one additional larger hose, disconnect it and start the engine. That valve is the air bypass valve, and will either route the air from the pump to the second large hose, or to the atmosphere via a couple built in silencer ports. It is controlled by the vacuum hose going to it. In one example, applying vacuum will direct the air out the second large hose, while no vacuum will cause the air to exit through the silencer ports. The other example is the opposite. With the second larger hose disconnected from the bypass valve, and the engine running, determine which system you have by applying and stopping vacuum to the vacuum port on the valve. Set up a vacuum supply hose that does whichever is required for your system to direct the air to the silencer ports (if no vacuum does it, disconnect and plug the original vacuum hose. If manifold vacuum does it, run a hose from a manifold vacuum source to the vacuum port on the valve). Take it for a test drive. If the valve that the smog pump hose goes to has two additional larger hoses attached to it, let me know and I'll try and guide you through that one.

 

It is the first sytem you are describing...only one larger hose.

Like I wrote in my above post, I disconnected the relay that must control that bypass valve. When I unplugged it my noise stopped as that valve stopped air from going through the tube. That being said, is the air now being constantly directed into the heads, or is it just being pushed through these "silencer ports" you talked about. I was wondering what the other relay next to this one was for...didn't seem to do anything when I unplugged it. Maybe it controls the bypass valve when the engine is cold? I am just curious if what I did is putting constant air into the heads, if this is damaging or not...