Crap... Just started hearing the tell tale sound of a rattle in the muffler. Starts at around 1500 rpm and goes on up to 2000. It's really loud when you rev it after it's warmed up.

I've not crawled under yet to verify that it's not just vibrating or hitting something yet, but have stood on the pass side and revved the motor with a broom handle and can clearly tell it's from the muffler area, so it's not a cat like I first suspected.

It's not even two years old yet...... Well, it's a good chance to check out a Magnaflow I guess. Still want a fairly quiet system with no drone in the cab, which the Gibson gave me, but stupid baffles get me every time. When will I learn!

 

Could it be a loose heat shield ratttling ?

Also another posting asked about the short black pipe that was on the stock system, which is a vibration dampener. Is this on the Gibson system ?

I think it was Don that said he has a rattle in his system on his L, and they retro fit 2 of these on there.

Just trying to get some background on the rattle, now that you have it narrowed down to not the Cat.

 

Thanks SSCULLY for the additional info.

It didn't have the damper thing on the stock setup. Never done it before either. I'll check the heat shields too.

I've had 'other' baffle type mufflers on various vehicles rattle the same way too. I've also had broken cats and know that rattle noise too well too.

Just need to get my butt under there, or better yet, I'll take it into a muffler shop to get it on a lift at lunch.

 

I have had a Gibson exhaust on two of my trucks. On the first truck I had a baffle break loose twice, but Gibson replaced the system both times. I just paid for a new system on my credit card and when they received my old system they credited my card back. It might be worth it to go this rought and save some money!

 

Thanks azboy. I've thought about that, and I do still have the original paperwork for the Gibson. I was always wondering how they did that replacement deal. That's cool if they credit your card. I assume it has to be another Gibson setup for them to do that??

Still don't know if I want to even bother with it. I've got a decent muffler shop and wish I had just gone there in the first place, but really liked what I heard about the Gibson, and it is exactly what I wanted in a muffler, but I don't have any luck with baffled mufflers for some reason!

Decisions, decisions.......... Thanks again for the suggestion.

 

Update. It was indeed the muffler that was making the noise. So, while at my favorite muffler shop, I asked about the Magnaflow and they said they would have to order it, so I then asked what they had in stock and it was Flo Pro and Flowmaster.

I had Flo Pros before on my 86 5.0 GT and Flowmasters are just not the sound I want.

Wow, what a difference in both throttle response and sound. The Flo's have this nice low rumble at startup and idle. Inside the cab, you can hear 'em, but it's not a drone at all.

I took the old Gibson with me and will see what it takes to send it in for warranty. If they send me a new one, I'll probably just try to sell it locally as I'm not going to put another baffled muffler on any vehicle I own!

Going to have to cancel my endorsement contract with Gibson too! Originally thought it was a pretty good muffler, but now that I've seen the other side, I'm changing my mind!

Thanks everyone for all the additional info on this.

 

The people at Flowmaster require you to reuse the vibration dampener, if equipped, when you put in a new exhaust system. If I were you I'd put that thing back on, it can't hurt...

 

I had a similiar noise with my sweptside. Upon inspection, it turned out to be a loose clamp between the muffler and the headpipe. I tightened it and no more noises. Could this have been the problem?

Did you notice any torque differences with between the Gibson and the new muffler?

 

I had the muffler guy put a scope on the muffler to verify that it was coming from there. No loose clamps, hangers or shields. Also no dampener to worry about. Didn't come with one.

Well, all I can say about the new muffler is that I have this hill I go up every evening. It's pretty steep and the speed limit is only 35 mph. With the Gibson, if I tried to maintain 40 mph, I'd lose steam about half way up and have to press the gas pedal more. This would cause the tranny to either unlock or downshift to 2nd.

With the Flo Pro, I can now maintain 40 mph the entire hill and only at the very top do I need to press a bit more on the gas. It does not downshift at all, and I have to make sure I'm not going 45!! Cops will sit on top of the hill and buzz you as you come over the top!!

The Gibson was a huge improvement over stock. The Flo Pro is as much or more of an imporvement over the Gibson IMO and SOTP feel. Looking forward to hitching up my travel trailer real soon too!

 

I towed my #4500 TT this weekend up and down I-5 to Portland and back and I have to give the Flo Pro another WOW!

I don't know what it did to increase my low end as much as it appears to have done, but it has......

I say this because with the Gibson, I could not really hold the rig in OD, even on level ground. I was pretty much able to cruise in OD now, as long as it was still pretty level and not too much head wind...... (side note, I still don't really like it in OD all the time, as I'm not convinced yet that I'm hurting the OD, but whenever I get a down hill grade or a tail wind, I will let it go into OD)

The biggest noticable difference was in climing up some of the hills. Not sure on the grade, but they are not what I would call steep by any means, but with the Gibson, I had a very hard time holding onto 55-60 mph without it wanting to downshift into second. With the Flo Pro, I just give it gas and I would start to actually gain speed! While still in third gear too!

I seemed to be able to get up to 60 mph a lot easier when merging too. I never had to put the pedal to the floor either. Something I did have to do with the Gibson........

The only thing I do have to say on the negative side of the Flo Pro is that it does have a slight drone in the cab when towing in third and crusing around 50 mph (around 2000 rpms). Not enough for the wife to comment on (yet), but I did notice the familar sound in my ears. The easy resolution is to not cruise at 50, as it does not do it going 60-65 in third or even in OD. Seems to be something with the 2000 rpms that sets it off. I can live with that!

Like I said eariler, I don't have any dyno numbers to prove any of this and it's only from my experience with the Gibson and the new Flo Pro that I'm basing any of this on. I will say that I am still using the Gibson 3" tailpipe, so that probably helps too.

 

Like JSCOTT, I had to retighten the clamp on the headpipe.

I'm surpised by what you say about torque with the Gibson. My boat can weigh anywhere from a minimum of 7000# to a max of about 7500#. Depending on grade, I can hold a hill at 55-60 MPH easy. It'll actually hold OD down to about 1100-1200 RPM and just sounds like a mule. If it's steap enough or long enough to need to kick it down, I can kick it down and once I get over or leveled out, she drops right back into OD. Never a hunt one. I'm actually amazed at how it will hold 3rd if I've hit a few steap grades in a row or kicked it down a couple of times. It'll hold until it reads my mind and I'm ready to cruise again. I think she loves me.

It could be a difference in trucks and mods, who knows. I know I'm real happy with mine. MPG is good even when towing too.

 

Hey FamilyRide, nice to hear from you. Have not seen many new posts from you. You must actually have a life and not spend it all here!

Seriously...... You have to remember that I've got the non PI 5.4, so I'm giving up 30 ponies and 20 lbs/ft of ***** right out of the box. (also only have 3.55 gears, 4x4 AND 31" tall tires!)

I was very impressed with the Gibson when I first bolted it on, as it was a huge improvement over the stock system. I'd still have it if it didn't blow a baffle...... I didn't even touch the clamp on the head pipe and the truck no longer makes the noise, so it was most definitely the old muffler.

Thanks for the comments and I hope you are still enjoying that boat as much as I am enjoying my new camper!

Mitch