mhill2079

98 4runner
3.4 v6
4wd
212,000 miles

About 2 months ago my truck started to make, what I thought, was a loud exhaust noise. First thought was muffler, had the muffler checked out and its in good shape. That guy said that he thought it was an exhaust manifold leak. So I made an appointment with a mechanic to have that checked. They said they couldn't really get it to make to loud noise but they guessed it would be the manifold but it wouldn't really be worth fixing for the price (about 470 dollars). So I waited to take it back to my hometown mechanic to have him look at it and after I got it to make the noise for him, (side note - it only does it in drive or reverse, if I hold on the brake and rev the engine to about 1400 RPM it starts but can go away if i go much over that. Some days it does it all day and some days it doesn't. Some days its really loud and some days it's not.) He thought it was the 'biscuit' in the catalytic converter and recommended replacing it or just putting on a test pipe. So I took it to another muffler shop with that info and after that guy heard the noise he said he would bet money that it was not in the exhaust anywhere. But didn't have much of an idea of what it could be. He said maybe a diaphragm in a pipe. Whatever... So then after talking to a few other people someone though maybe an engine mount had broken, as it seems to only make the noise when there is a load put on the engine. (like I said before it will never do it in park or neutral).

Kind of at an impasse here and not really sure what to do with it. I don't want to just start throwing money at random things hoping it will get fixed. Also the one mechanic that thought it may be the converter said he plugged the muffler with some rags to try and recreate the noise but it didn't get any louder. I am starting to lead towards its just something rattling with the exhaust but not sure.

Any thoughts?

mhill2079

Damn no ideas? well today I took it back to the original muffler guys that said it wasn't the muffler and I was gonna have him cut off the catalytic converter to run a test pipe to see if that cleared it up. He was also the one that initially thought it was the exhaust manifold. And after looking at it again today. ( I went up on the lift in my truck and reved up the engine so he could inspect the underside while it was making the noise) He said, yep thats a bad muffler. WTF. So what he is saying is that the outside layer of metal is getting thin (on the bottom of it) and it has a spot that starts quivering and making a loud rattling noise at a certain RPM. He pushed on it and dented it a little at the noise has almost all but stopped at this point.

drpdmazda

do you have a vid of the noise? is it possibly the flex plate? the flex plate makes more of a pinging or ticking, but when mine was bad it would come and go with the rpms also