Its been a long time since I have been on here. I have a wierd rattle at highway speeds. The wierd part to me is that it does not do it all of the time. It will start and stop at random times. At lower speeds it does not do it at all. The noise sounds like in is right under the pass. floor. Sometimes it rattles if you hit a bump a sertain way. It sounds like something is broke, but I can not find anything wrong. Any ideas?

 

Hows the cat. It could be in pieces inside.

 

I have tapped on the cat and does not rattle. You would hear it ratteling right? I forgot to add it makes the rattle more often when I am pulling my boat. This thing has me stumped. I can't figure it out...

 

Are you sure its not pre-detonation (pinging)? Have you checked the plenum? Usually itll ping under a load or uphill or under heavy throttle, ect. before it will under "normal" driving.

 

I have not checked it reciently. It was leaking about four years ago and I fixed it with the one that hughes engines makes. What ever this noise is once it starts it will do it if you let off the throtel or step on it. When it does this it may do it for about 30 seconds or so and then it may not do it for another 10 minutes and some times it will be even longer. The only time I have noticed it do it more often is when pulling my boat. This summer I was going up a really steap hill and it did it the whole way up. I thought about the CAT, since it is the only thing under the PASS floor board, but there is no egg smell or ratteling when I bang on it. Maybe I need to try to bang on it when it is hot? What do you think.

 

rattle, bumping, thumping under the driver or passenger feet is loose lower front shock bolts. they have to be torqued to about 110 pounds, which is tight as hell.

 

Yup. This also. I forgot about them.

 

I will check these bolts and let you know... thank you...