peezy

So first off i have a 1998 f150 4.6L v8. About a month ago i started hearing a knocking type noise and figured it was a exhaust leak. Now it is getting louder and i need to get it fixed. The sound only happens when the vehicle is cold and you can slightly hear the sound when the vehicle is hot.

I have traced the noise to the drivers side and under the truck around the manifold and cat flange. Other then that i cant pin point the noise.

I have tried the soapy water trick and blocking the exhaust tip but with no luck at finding the leak.

All the studs look to be fine and not really rusted. A engine was dropped into the truck so i think they didn't replace the manifold as that's really rusted.

Is my manifold warped or is there another problem? I am thinking about taking it in so someone else can check it out but i would like to see if i can pin point the problem first.

Here is a video i took when the truck was cold.
http://s1128.photobucket.com/albums/...43D2E36580.mp4

i really need help so the problem does not cause a big problem.

peezy

no one?

Stimmel.20

did you check the egr tube?

peezy

No, how should i check it? I took a look at the oil filter to make sure it was not a fram and its a premium guard.

When i get home i will check the egr tube, thats the tube going into the manifold correct?

Stimmel.20

Yeah its the tube going to the manifold. Mine has rusted out where it connects to the manifold and leaks real bad. I didn't notice it was coming from the tube for awhile so I thought I'd throw it out there.

peezy

I will let you know, it might be the tube as all the studs on the manifold are not really rusted. etc, how much does a replacement tube run?

peezy

ok so i think i found a leak, i did the hose trick and located air coming out of the bolt holding the egr tube to the engine not the manifold side. so could that make a pretty noisy sound?

1997F150XLT

Oh yea it's gonna be loud.

peezy

ok, sweet now i know where to start working, going to replace the egr tube, put new oil filter on and put 5w30 motorcraft filter/oil semi-syt, and go from there hope this will fix the problem!

peezy

The problem is still present. It did reduce the sound but i still have it. I need to get a stethoscope to pin point it, But i think it is Piston Slap. I have a 97 windsor 4.6 engine.

What other steps i can take to figure out whats causing the noise?

This morning it was making the noise, it went away about a min or two after i started the truck. When i gave it gas the sound went faster, Not really louder just faster.