Thumping noise at low revs under load

Armkb, thanks for the sound clip. My sound is similar but not as pronounced. And I don't get the noise unless I have a load on the engine, like when I'm driving uphill. You're the second person who has suggested that the intake on the passenger side fender might be the source of the problem. I will definitely check it out.

 

My soundclip is uphill under load in my driveway. I will bet what you are hearing is the intake. I had a hard time believing it was the snorkel as all the noise was eminating from the driver side down by the floor. Thought for sure it was an exhaust leak. Would have never checked the intake if it wasn't suggested here on TW.

 

Armkb, how did you fix the gasket? Thanks!

 

That's the same with mine. When I say idle, I mean idling under load(in gear) without giving it any gas and have the brake on. When I give it gas the noise speeds up and fades until about 1500-2000 RPM then I can't hear it at all. It also pretty much disappears when I put it into neutral. I'll keep you posted anyway if I find a solution!

 

I just added more foam tape around the existing foam. As I suppested to Saskabush just take the tube off temporarily to see if noise goes away. Very easy to remove.

 

Armkb, thanks! I'll try adding more foam tape.

 

I took the tube off and the foam is pretty crushed, so I will definitely add some some foam tape over it as Armkb suggested. But I also noticed that there are three holes drilled into the bottom of the tube (see picture). They kind of look like they were done by the previous owner. I couldn't find any pictures that would tell me if the holes are supposed to be there or not. Does anybody know if the holes are supposed to be there? If not, why would somebody drill the holes? Should I try to close the holes, possibly with a little bit of foam tape? Thanks!

 

oil pump struggling when truck is at an incline? Left bank gets a little starved of oil, can cause noise? Just a guess? Maybe start the truck, put a jack on the front center jack point and start slowly jacking it up see if you hear any difference in engine. If you have an oil pressure gauge, hook it up and monitor oil pressure as you jack up the front end.

Just a guess.

 

Don't know about the holes. Did you drive it with the tube removed? Is the noise gone?

 

LJ, I did drive it with the tube removed. The noise is not completely gone, but it is less noticeable. I finally found a picture of the bottom of the tube. It was not the same angle as the picture that I took, but it did look like it had the three holes. So I'm going to leave the holes, add some foam tape over the existing foam and put it back together. I'm beginning to wonder if the sound I'm hearing is actually from the exhaust and/or cat. I didn't see any holes in the exhaust and it looks stock, but it does sound almost like an after market exhaust, more of a rumble/burbling sound. Maybe its always there and I can only hear it more clearly at low revs going uphill. I sure hope its not the engine! Thanks!

 

Leave the holes. They are factory and meant for water drainage.

 

Armkb, I did leave the holes. I put the foam tape over the existing foam and put the tube back in place. I may just being optimistic, but I think the "thumping" noise may be diminished. Thanks for your help!

 

jboudreaux1965, I will check into the oil pump. Thanks for the suggestion!

 

I drove for a few days and unfortunately, adding more foam at the air intake did not eliminate or diminish the noise.