jonothejester

I have 1994 Ford F150 5.8L. About 3 weeks ago I started hearing a hissing/squealing (more of a hiss than a squeal) sound from the engine. I took a look at it today and couldn't figure it out.

The noise happens all the time when the truck is running. Sometimes if I go above 45 mph then I think it will either quit or quiet down but it could just be the sound of the engine drowning it out. Whether the air is on or off or the accelerator is pushed or not, it is a consistant noise.

What I have done so far.

I thought it was a pulley going bad so I took off the belt and ran the engine for a about 10 seconds and it still hissed/squealed. This elimated the pulleys.

It sounds a little louder on the left side of the engine block than the right (looking at it from in front of the truck)

I am uploading a youtube video of it...although you can't really hear it because of the hissing mixed in with the noise of the engine, but it will give you a visual of my engine.

I'm not sure if it is something vacuum related or how to verify that it is.

jonothejester

Here is the link to the youtube video...poor quality though. I will try to upload another with better quality. Let me know if you want me to zoom in on anything imparticular. Thanks.

Ryan324

almost sounds like a vacuum leak...check how many inches of vacuum in has at idle and at 2000

jonothejester

What is your recommended tool for testing vacuum (link) and where do you hook it up at?

Ryan324

http://www.autozone.com/autozone/cat...ressure+Tester


hook it up to break booster line

Ryan324

also check to see if your pcv valve has come off

jonothejester

Is this my pcv valve and if so should it have a hose going to the top part of it? (see the video)

jonothejester

I think I have figured it out. I replaced the pcv valve and no change. However, upon further investigation of all my vacuum lines and what I read online people were saying that the egr valve could be stuck or sticking. I started to remove the egr valve to clean it and noticed that my egr tube was loose (the tube coming out of the bottom of the egr valve and going down into the engine. I took a closer look and at the bottom of it, it was rusted through at the bend.

I ordered a new one and it will come in a few days. I will let you all know if that solved the problem, which I think it will.

jonothejester

Welp...I replaced the EGR tube and it was basically rusted into two pieces. However, it did not help the hissing sound. However after replacing the EGR tube, now my truck runs pretty rough, shakes quite a bit more than usual when in gear and has a lack of power when accelerating.

Thinking it may be the EGR Valve or Gasket, I replaced those also...no imporovement on the hissing, running rough, or lack of power.

Any suggestions?

jonothejester

Update:

A couple days after replacing the EGR Valve the hissing magically stopped...go figure.

I think the roughness while it runs is due to a dirty air filter and the secondary filter for the other tube coming out of the air filter box.