Anyone else get a grumbling/vibration under your feet?

When I come to a complete stop at a red light, I get a vibration I can feel under my floor drivers side floor board and grumbling, almost grinding sound from somewhere under the front of the truck. Never while in motion, always after I'm stopped for a couple seconds. Very strange. Anyone?

 

Something loose vibrating maybe? Climb under and start grabbin stuff. Skid plate?

 

I took a good look, skid plate is off. Could it be something in the brake booster? It feels like it's at the bottom of the firewall in the engine or close to it

 

Bad motor mount? Tranny mount?

 

Bad wheel bearing?

 

I didn't even think of a bad mount since it only happens when the truck is at idle. Am I looking for cracks?

 

Could be as I hear a canary singing on the driver side when I take off from a stop. It was worse before I changed my drivers side cv axle. Noise had lessened but not gone away.

 

So the problem is still there. In drive, come to a complete stop. Almost a pulsing, rhythmic groaning sound. Doesn't do it in park and I can't hear it in the engine bay. Very noticeable in the drivers seat though. Almost like a pump is struggling somewhere.

Awhile back I had a chirping sound when taking off from a dead stop. I figured it was my bad cv axle on the drivers side so I just drove it until I could fix it. After the axle was replaced I could still hear it. I changed my trany fluid a few times as it was like dirty motor oil. Doubts it's ever been changed. After a few drain and fills the chirping has gone away almost completely. Guess it was something in the neglected trans. I wonder if the current and always present grumbling is something in the trans? Is there a pump in there? I'm guessing trans as it doesn't do it in park, only in gear.

 

Is the grumble there while in neutral ?

If not, I'm thinking the torque converter. I've never had problems in all the vehicles I've had with automatics, but thats all thats left, if you have ruled out the 3 motor mounts.

Have you re-checked the tranny fluid level?

 

Fluid sample, pull a quart or so, Start at the Tranny.

You say it sounds like a pump struggling in drive. Did it downshift all the way? What's your idle at?

Does it grumble after a few seconds of sitting idle, or for a few seconds?

Slushbox diagnosis is a toughie sometimes, so have to ask questions.

Grumbling in drive can get real spendy real fast.

 

I've only noticed it in drive. I'll check in neutral when I drop it off at the audio shop in a minute.

 

My idle is just above 500rpm in drive when at operating temp. Since having the truck I haven't checked or cleaned the IAC valve yet. I'll dive into the throttle body cleaning tomorrow morning.

I just dropped the pan to change the screen filter and clean the magnets. I'm going to take it for a good drive in a minute and I'll shift it in to neutral when I come to a stop at a red light.

It does it after a few seconds of coming to a stop AND it lasts for a few seconds.

 

Do you have a lift?

 

Just checked it. Once I stop at a red light it starts after a few seconds of sitting there I shift in to neutral and the noise disappears. Now I'm a little worried about the cost of this issue.

 

Yes 3" but I'm unsure of the manufacturer or model of lift.

 

I'm willing to bet that's the root cause. I have had the same noise on both trucks I've owned with a lift.

 

btw, I do not have a lift but do have a slight rumble in D at a stop. The 500 rpm is the culprit, if you hold the brake and tap the gas so it goes up to 650-700 it usually is fine, AND the lights (at night) are dim until it gets back to the 650+ range.

Been too cold to do any work but more cleaning is in my future.

 

Aside from gassing it at a stop, any idea for a fix? Cleaned my tb and iac as well as the MAF along with new plugs. Still have the rumble.

 

Had a 85 SR5 5 speed that had a home brew 2" body lift and I could hear the body was drumming in certain gears. A damn good idea to check for loose lift mounts, trans mounts, engine mounts body or suspension before you crank out the serious tools and cash.

A/C unit is in good shape? That kicks itself on and off whenever it feels like it for heat or a/c and could cause a rumble in drive.

 

Maybe a dumb question but how can you tell if a motor or trans mount is loose or bad? Do you try and shake it or move like when checking for a bad ball joint?