SOLVED - Questionable noise when cold and under load

[thefrey]

This noise recently developed:

CEL is for cats so it's unrelated.

You don't hear it at idle, it becomes apparent at about 2k rpm under some moderate acceleration, and it goes away when warm. I haven't done much staring under the hood yet, but I don't really know what this noise would be...

I have a new(er) serpentine belt (10 months) and new AC belt. I know my tensioner is quitting (it's bouncing around when running) so not sure if that would be causing the noise, but I feel like it would happen all the time if it was the tensioner.

I might have a slight exhaust leak.

Dunno what it is. Figured I'd come here and see what ya'll think.

 

[ReaperHWK]

Sounds like an exhaust leak at the manifolds to me. If it goes away when it’s warmed up that would be a tell tale sign as the manifold expands and fills the “leak”.

 

[thefrey]

Sounds like an exhaust leak at the manifolds to me. If it goes away when it’s warmed up that would be a tell tale sign as the manifold expands and fills the “leak”.

Huh, interesting. I didn't know an exhaust leak could sound squeaky like that.

 

[OR VietVet]

CEL for cats and you don't think is related? How about clogged cats and back pressure causing problems?

 

[thefrey]

CEL for cats and you don't think is related? How about clogged cats and back pressure causing problems?

I don't think it's related.

I don't have any loss of power or MPGs, my cat codes are for both banks, and I was/am an idiot and installed my exhaust manifold gasket wrong the 1st time. I fixed it but I don't think it's sealing right.

Cat codes came up before I did exhaust manifold gaskets or my DOD delete so I think the cats are just tired. Not sure. I don't have emissions though and not sure if I want to sink 3k into new cats.

 

[15burban]

If you don't have emission testing you can pickup universal cats for a lot cheaper and weld them in. Or make the current ones "lighter" and get some spacers for the rear 02 sensors to keep the code away.

 

[thefrey]

If you don't have emission testing you can pickup universal cats for a lot cheaper and weld them in. Or make the current ones "lighter" and get some spacers for the rear 02 sensors to keep the code away.

I may keep my current cats and just keep an eye on them with spacers. Or just do a lil' bit of weight reduction and get some spacers as well.

I figured they're still "working", but just not as efficient, and it probably doesn't hurt to keep them in as long as they aren't clogging. I don't know how stinky catless would be but figured having some cat material in will help unstank the stunk.

 

[rdezs]

Hard to diagnose off the internet, but yeah, it sounds like an exhaust leak to me.

I suppose it's plausible that could trip a code for the cats, depending what the downstream sensors are detecting....

Easiest way to do those exhaust manifold gaskets.... Install two or three studs, stainless steel preferably.... Hang the gasket on them, then the exhaust manifold. I use nothing but stainless steel studs these days, the ones with an allen head in the end. Then I use stainless steel star washers followed by stainless steel nuts. Never had an issue.

 

[thefrey]

Hard to diagnose off the internet, but yeah, it sounds like an exhaust leak to me.

I suppose it's plausible that could trip a code for the cats, depending what the downstream sensors are detecting....

Easiest way to do those exhaust manifold gaskets.... Install two or three studs, stainless steel preferably.... Hang the gasket on them, then the exhaust manifold. I use nothing but stainless steel studs these days, the ones with an allen head in the end. Then I use stainless steel star washers followed by stainless steel nuts. Never had an issue.

I have both a 420/430 code. It's kind of confusing me because I had the code first initially trip the night before I did my DOD delete (and before I touched anything) so it might just be tired cats at this point... I don't have any loss in power or gas mileage. I suppose an exhaust leak could make the issue worse, but I don't know how much chasing the code for the cats will do for me. I am just confused they both came on at the same time.

I do have all stainless bolts for my exhaust manifolds. I got decently lucky and all my broken studs came out with vice grips when I had everything apart.

 

[LsHart]

Gut the catts?

 

[LsHart]

Doesn't work for everyone.P0420 AND P0430 are restriction codes. If I remember a exhaust leak before catts would throw a lean or rich code(if any) for the O2s.You would be surprised on how peppy it would be once catts are removed or replaced. So drives like normal is because u are used to driving it like that. Codes are telling u something.

 

[LsHart]

I don't think it's related.

I don't have any loss of power or MPGs, my cat codes are for both banks, and I was/am an idiot and installed my exhaust manifold gasket wrong the 1st time. I fixed it but I don't think it's sealing right.

Cat codes came up before I did exhaust manifold gaskets or my DOD delete so I think the cats are just tired. Not sure. I don't have emissions though and not sure if I want to sink 3k into new cats.

I went back and read this. Codes are for both banks? 420 and 430 are forward catts and or rear(aftercat). So now(this is a question) if now running on all 8. The catts are getting the full load of exhaust and fuel. I almost bet if u remove the DOD the light wouldn't come on for a while if any. Engine goes from 4ish highway cylinders to all 8 non stop. Computer reprogram or just as u said tired catts? I am by no means trying to jab per say, just wanna help if anything.

 

[thefrey]

Gut the catts?

I’m tempted… my biggest worry is smell. I drive a good amount and don’t want the car smelling terrible. My thought is that the cats might be working, just not as good as new.

.P0420 AND P0430 are restriction codes.

Maybe I am wrong in this, but I thought these both pointed to cat efficiency and had nothing to do with restriction since the downstream o2 is measuring how efficient the catalyst is. I plotted my o2 sensors and they are both mirroring or following the upstream sensors. I believe some of my honeycomb is starting to fall apart too.

I almost bet if u remove the DOD the light wouldn't come on for a while if any.

I have had DOD disabled from 202k-215k and I did a full DOD delete with camshaft and lifters at 215k. I have had the code since 215k (literally the day before my DOD delete) and I am now at 223.5k. I have tried to clear it multiple times and it has come back usually within 100-200 miles

The only perhaps red flag is the code popped up the day after I got DOD tuned out in my ECU at 215k and maybe something happened there?

Not sure at all. I appreciate all the thoughts but not sure where to go from here. I am not too worried about the cats since I don’t have emissions and the 420/430 codes are more of just a nuisance for me. I just don’t want smell or a super loud sound increase. I would enjoy more sound but I drive 25k a year right now and a lot for work

 

[thefrey]

Turns out it was an exhaust leak. New driver side manifold gasket did the trick. Thanks ya'll