I am not even sure what kind of search to do for this /these issues.

'94 xlt 4x4 351 auto.

1st. makes a noise like an exhaust leak at the donut on drivers side but there is no leak. loud.

2nd. under excleration a whoosing sound comes from under the hood, sounds like air trying to get past or through something, on the highway after about ten minutes of speed the sound will start and then eventually joined y a second noise simulair in nature but more mechanical with a slight vibration. Truck starts to loose speed no matter what RPMs. Seems like a vacuum leak to the tranny but I can not find one.



3rd gas milage is down.

had a tune up 5g's ago.

I know I do not contribute often, but life takes over and this has been a busy wacky kind of year.

any ideas or suggestions?

 

Check the air tube across the back of the motor, it's for the air injection system and connects to the exhaust via ports at the back of the heads. This tube and the check valve attached will corrode and break sooner or later.

 

I second the air injection tubes for the system.

 

I was trying to get a good look at that but just can't seem to get close enough. I can see where the tube starts on the exhaust manifold but then loose it behind the engine. I did not know it had a check valve. I will climb in under that hood tomorrow as it is late.
Happy Halloween!!

 

ok, so I finally crawled into the engine compartment. It was dark and I did not have much success in locating that tube and check valve. mostly because I was looking at the wrong tube. Great. Will try again tomorrow.

I went and looked real quick again and I was looking at the right tube. I think. connects to the exhaust manifold on the divers side and disappears behind the engine. I think I can see the check valve on the passanger side. Where dose it coonect to the air injection system?

 

Couldn't the wooshing sound be a bad fan clutch?

 

good point, I am not sure that would account for the lose of power.

 

I agree with Conanski. Sounds like the check valve rusted and separated from the tube. Mine was like that when I bought my truck. Makes a loud exhaust leak sound, and when you step on it it sounds like sucking air. You can get up under the hood and follow with your hand from one head to the other. In the center (roughly) there is a round check valve that should go up to another tube. It breaks right there in the center and you'll feel an open hole there.

 

rrrrrrrraaaaaaaaaaaaaagh.

Ok I know how this looks, he has to get his priorites straight. In my defense I have been working OT and the hours are crazy. Plus I perfer to spend time with my 7yo daughter.

I tried to loo last night but when ever I climbed under the hood someone would call me for something. So,TONIGHT I will FIND that damn tude and valve. Just wanted to let all who have been kind enough to respond I am still working the prob but just alittle bit busy.

How crazy have thing s been? some jerks STOLE my commuter car and took the tires and car parts in the trunk. JERKS. That is what I get for having nice tires on it.

 

that sucks dude, i would also replace the fan clutch they are pretty cheap and they will account for a loss in power as well not sure if it's as dramatic as what you are seeing but something to think of it that valve thing doesn't work out for ya

 

trying to post/inssert a pic of the check valve

 

https://www.ford-trucks.com/forums/4...e-display.html

 

Lets try this photo thing again.

Is this the check valve? If so isn't that the fuel rail/line it is attached to? To solve the problem do I replace the whole rail. Plan on looking at online parts to help determine this. And finally I could not find any holes in the tubing that comes from the head. I also sprayed the area with carb cleaner and did not notice a change in the idle.

 

Fuel pressure regulator?

Can you see/feel a tube connecting the back of your two cylinder heads together?

 

Reach back BEHIND the heads, between the heads and firewall. There should be a BIG tube about 5/8 in diameter. It will be BOLTED to each head.