98 front rattle when stopped in gear

[lgc285]

hi guys. just bought a 98 limited 117K. *seems* to run great. but today a rattle started in the front end. it was only happening when the truck is stopped, foot on the break. It went away when I shifted into neutral, but started again when I put it back in drive. once I hit the gas...runs smooth again with no noise. at next stop light, same thing, the rattle started again...

transmission seems to shift smooth and clean, break pedal seems a little spongy... definitely coming from under the hood. any help is appreciated!

pretty frustrating. wish I knew more about trucks!

 

[Jc12]

can't give you a definitive answer but you will probably be at a different RPM while sitting in gear vs neutral and obviously when you are accelerating. I have had cars with heat shields, bolts etc etc rattle at just a certain rpm then disappear once i accelerate or go into neutral. May involve crawling under it..

 

[JBurt]

There could be a lot of different causes. There are a lot of different types of rattles too. Your best bet would be to post a video or sound clip. Good luck.

 

[MattAK]

Did you have your air conditioning on? I've noticed last summer my '01 rattles a bit while in drive, stopped, with foot on the brake, and the AC compressor is on. Shifting into neutral ups the rpm's of the engine and it stopped. Also would stop if I turned off the AC.

Edit: today was warm enough here to use the AC for the first time since October.

 

[lgc285]

thanks guys. what a great resource. turns out it was not coming from under the hood but it was circular clamp right near the catalytic converter i think? basically right under the passenger seat. It has rusted out on one side and is rattling pretty loud.

Easy fix I hope? any suggestions on best place to order a new piece?

 

[pattycakes77]

I was going to suggest looking at the exhaust. My exhaust damper bracket rusted away and the damper fell off, shortly after I would get a rattle at idle but not in gear. Turns out that little damper does do something! I got a new one that I'll clamp on one of these days.

 

[BrianSD_42]

When I had a rattle exactly as you described it was from my air intake being loose.

 

[lgc285]

can I get a replacement piece just about anywhere? ill try to get a pic of it