Alarming rattle can noise from under truck

[Scott6]

I posted this on another forum, but I have been wanting to give this place a try. Getting kinda tired of all the delete talk, same thing over and over and over. This seems like a cool place for just the truck stuff.

Anyways, The issues I'm having is when the truck is cold. Only when real cold, like overnight outside cold. It will make a alarming chatter, like a rattle can when accelerating. It doesn't do it after a day of sitting in the parking lot at work, Doesn't do it in reverse, park or nertural, only in forward gears it does. It only does it for 30 seconds or so of driving then stops. If I let the truck idle for a few mins that really helps it a lot, sometimes when it gets 10 mins to warm up it won't do it at all.

Truck has no other symptoms, runs great, shifts just fine.

The basis:

• 2008 2500, 4x4, 3.73:1, 68RFE, 94k on the clock
• All fluids are proper levels (trans, diffs, x-fer, oil, PS)
• Oil is at 9k, Shell T6 - I have new stuff in the garage, working on getting to it (shouldn't matter)
• Fuel filter is at 14k, again almost near a swap (shouldn't matter here)
• Trans fluid was changed at 36k, so I guess I could be near a service there.
• Truck tows my 5er around, but since we moved to Tx I haven't been camping so its been 25k of no load.
• I was using a 40-70hp tune when unloaded for a while, stock when towing, but its been on stock hp for some time now, I just didn't need the power and MPG gain was negligible at best. Not worth it.

This morning I chalked the front tires and jacked up the rear end. I made a video and move the camera to different spots. It defiantly sounds like its form the trans area, not under the hood. The first rev is in Park, no noise. Then I moved it to drive and let the back wheels spin, it's very obvious when you hear it.

(Admin note: broken video link removed)

 

[GCroyle]

Scott,

Welcome to TDR.

Good info and video for your concern. I'm passing on guessing cause that's what I'd be doing. I bet somebody is gonna chime in a offer ideas. OK gotta try one idea. Have you gone under truck and tapped on any heat shields? I don't even know if your truck has any but what the heck.

Good luck,

Gary

 

[DavidC]

Have you checked your torque converter to flex plate bolts under the bell housing cover ?

 

[Scott6]

Good info and video for your concern. I'm passing on guessing cause that's what I'd be doing. I bet somebody is gonna chime in a offer ideas. OK gotta try one idea. Have you gone under truck and tapped on any heat shields? I don't even know if your truck has any but what the heck.

Thanks bud. Ill check those just in case, but since it only rattles in gear I'm thinking its driveline

Have you checked your torque converter to flex plate bolts under the bell housing cover ?

Ill give those a check tonight. If its got loose flex plate bolts it seems weird that it stops after only a few accelerations. The Its only been doing it for 2 weeks. First time I heard it was 2 weeks ago, then not again for a week, now its every morning. So it is getting more frequent. Again temp could come into play here. It did get cold!

Texas, Summer, Windows, Fall and Spring in one week.

I need to get under it while its making the noise, but I need to find a safe manner to do so. Sounds like its coming from the trans pan to me. A man drop might be in order. Im hesitant to take it to a trans shop because it won't do it by the time I get there lol.

 

[DavidC]

Thanks bud. Ill check those just in case, but since it only rattles in gear I'm thinking its driveline



Ill give those a check tonight. If its got loose flex plate bolts it seems weird that it stops after only a few accelerations. The Its only been doing it for 2 weeks. First time I heard it was 2 weeks ago, then not again for a week, now its every morning. So it is getting more frequent. Again temp could come into play here. It did get cold!

Texas, Summer, Windows, Fall and Spring in one week.

I need to get under it while its making the noise, but I need to find a safe manner to do so. Sounds like its coming from the trans pan to me. A man drop might be in order. Im hesitant to take it to a trans shop because it won't do it by the time I get there lol.

Yeah I thought it would be weird also but you never know. Take a close look at the flex plate also.

 

[Scott6]

So what am I looking for? I assume loose bolts and cracks. I didn't think I could see much of the flex plate from the housing cover. But I have never looked for issues there so yea... Ill get a light and go take a look this evening.

Also just for kicks, I plugged in Smarty Jr in, I guess I was running SW1 default settings so I am running a little more timing that stock, 40hp is what they call it. I do drive conservatively (19.5 average mpg) so that should not be an issue. Not sure if I will bother loading SW0 or not.

 

[Bob4x4]

Not just loose bolts,but check for cracks and or elongated holes.While driving get on and off the power.

 

[Scott6]

Not just loose bolts, but check for cracks and or elongated holes.While driving get on and off the power.

Ok cool, thanks. I didn't thing I would be able to see all that much of it, but I will look. I did get in an out of power on the highway, no issues at all. Felt smooth and strong just like normal. It even feels fine when its making the noise, it just makes noise.

 

[DavidC]

Rotate it with a big screw driver. Teeth and bellhousing make a good pry point. That's the way I do mine to get to the torque converter drain on the DTT converter.

 

[Ozymandias]

If it is only in Forward Gear (not in Reverse) then it is not Engine or TC.

 

[Scott6]

Did some YouTube and found where the access cover on the passenger side to get to the flex plate bolts... looks like fun.

 

[Scott6]

If it is only in Forward Gear (not in Reverse) then it is not Engine or TC.

Thats kinda what I was thinking... I was very careful to test in reverse. I actually have a 60' driveway I back out of most mornings I do get a little exhaust vibrations form the 100rpm drop in reverse (due to my hack up exhaust piping.. I need new) but defiantly not that noise. Im gonna scope the sound but I feel like its coming from the pan (IE) valve body.

 

[Scott6]

IDK guys I got under the truck and removed the cover. Bolt all look good, no play between converter and flex plate. "looks good".. some oil form a slowly leaking rear main seal (years in the making haha), but otherwise looks ok. Its really weird to me that such a loud and clean that just goes away can be anything on the drive line. Like it should be there all the time. Maybe im being hopefull

 

[brucejohnson]

Boy, this is a tough one without being there. I wish you would have reved it a little higher to see if the rattle changed. Initially it sounded like a fan blade/shroud kissing, but they aren't metal and the video sounds were not right. Then the revs seemed to synchronize with the rattle, so it sounded like RPM induced, like a loose bolt or strap swinging out. But the timing of the sounds just didn't fit the items slinging around. I was thinking what could make the metallic sounds. If the RPMs had more range would help some. In forward gear only...that really throws a curve ball.
Heat shield: should do it all the time at a harmonic with the engine.
Flywheel/torque converter: Loaded/ unloaded - should be consistent forward/reverse.
Transmission: Loose screen, parts in pan, things spinning and clacking. Inconsistent with selected mode drive/reverse and tinny metallic sounds. I believe in reverse it is still flowing fluid through the pickup as it does in forward gears, so no change in the pan. Still, not totally excluded...
Drive line not spinning fast enough to emulate the rattle.
Engine oil pan, sounds from underneath don't sound like they are coming from the pan. Anything in the pan area whapping like that should have flung out the side of the block by now.
Now lets look at the exhaust.
To me, it sounds like a loose baffle in either the muffler or loose guts in a catalytic converter, or other exhaust device. I would choose the muffler over the converter because of the tinny metallic sounds. A slight torque applied to the muffler through the exhaust pipe in one direction may loosen the baffle just enough to rattle consistent with rpm and exhaust flow until the heat causes the metals to expand and the rattle ceases. In reverse, the torsion applies pressure to the parts and prevents the rattle. No torsion, in P or N insufficient torsion to loosen the baffle enough to rattle mode.
Of course this is a WAG, but the sounds on the video sure do sound like bad exhaust internals or touching something.
Best way is get under the secured truck and have someone go though the rattle procedure while you check each suspected component.
Happy troubleshooting!

 

[Scott6]

Boy, this is a tough one without being there. I wish you would have reved it a little higher to see if the rattle changed. Initially it sounded like a fan blade/shroud kissing, but they aren't metal and the video sounds were not right. Then the revs seemed to synchronize with the rattle, so it sounded like RPM induced, like a loose bolt or strap swinging out. But the timing of the sounds just didn't fit the items slinging around. I was thinking what could make the metallic sounds. If the RPMs had more range would help some. In forward gear only...that really throws a curve ball.

Yea the sound is defiantly under the truck, near the middle by the trans/cat. I was a bit rushed because I had to go to work and it was a quiet early morning. If I dont get anywhere new Ill make a better video this weekend when I have time to setup safety stands for the rear. I will try for more rpm range, but it does seem stop at higher RPMs or minimize enough to make it hard to hear. I think its getting worse too, seems to be doing it even when not cold now. Im not going to drive the truck tomorrow

Yes the noise is with revs. Its hard to hear because the truck is so loud but I dont think it makes the noise at all during idle, or even neutral acceleration, like really? WTH. So it needs some load, further pointing to small newish cracks not loose bolts. forward gear only wtf right?

Now lets look at the exhaust.
To me, it sounds like a loose baffle in either the muffler or loose guts in a catalytic converter. I would choose the muffler over the converter because of the tinny metallic sounds. A slight torque applied to the muffler through the exhaust pipe in one direction may loosen the baffle just enough to rattle consistent with rpm and exhaust flow until the heat causes the metals to expand and the rattle ceases. In reverse, the torsion applies pressure to the parts and prevents the rattle. No torsion, in P or N insufficient torsion to loosen the baffle enough to rattle mode.
Of course this is a WAG, but the sounds on the video sure do sound like bad exhaust internals or touching something.
Best way is get under the secured truck and have someone go though the rattle procedure while you check each suspected component.

Heat shield: Yea, the shields are all nice and tight.
Flywheel/torque converter: makes sense to me
Transmission: Im considering a pan drop and inspection on Sat..but it seems much too loud and tinny to be something loose in a pan full of thick fluid.

Now lets look at the exhaust.
To me, it sounds like a loose baffle in either the muffler or loose guts in a catalytic converter. I would choose the muffler over the converter because of the tinny metallic sounds. A slight torque applied to the muffler through the exhaust pipe in one direction may loosen the baffle just enough to rattle consistent with rpm and exhaust flow until the heat causes the metals to expand and the rattle ceases. In reverse, the torsion applies pressure to the parts and prevents the rattle. No torsion, in P or N insufficient torsion to loosen the baffle enough to rattle mode.
Of course this is a WAG, but the sounds on the video sure do sound like bad exhaust internals or touching something.
Best way is get under the secured truck and have someone go though the rattle procedure while you check each suspected component.
Happy troubleshooting!

The sound is defiantly up near the front, but I have not ruled out the CAT either, good thinking! "taping" it with a 4# does not produce any rattling though. Funny because I do have a Cat test pipe sitting in my garage that I never got around to installing. I kinda liked how to took down some of the smell and it does quiet it down alot, and heat, its nice doubled walled setup. If I can better ID the source this weekend maybe that all goes down.

Happy troubleshooting!

Thanks bud! Well see how Sat goes I almost never go to a shop, but this might be one of the few times. Not sure im willing to pull the trans, heck imid be in $250 just for the Jack needed for the trans, and some real HD ramps to saftly get the front up high enough to pull it.

 

[Scott6]

Fired it up this morning and did some more listening. IDK, it might actually be coming form the cat (or something in the exhaust). That would make more sense as to why it stops when it warms up a little, but it doesn't line up with why only in gear? (unless it needs some boost to occur. Maybe im being optimistic, really not wanting to pull the trans IDK.

Took the wife car in today, first time my truck has ever made me take another car to work Gonna grab an automotive stethoscope on my way home and start poking around.

 

[tommyturbo]

I posted this on another forum, but I have been wanting to give this place a try. Getting kinda tired of all the delete talk, same thing over and over and over. This seems like a cool place for just the truck stuff.

Anyways, The issues I'm having is when the truck is cold. Only when real cold, like overnight outside cold. It will make a alarming chatter, like a rattle can when accelerating. It doesn't do it after a day of sitting in the parking lot at work, Doesn't do it in reverse, park or nertural, only in forward gears it does. It only does it for 30 seconds or so of driving then stops. If I let the truck idle for a few mins that really helps it a lot, sometimes when it gets 10 mins to warm up it won't do it at all.

Truck has no other symptoms, runs great, shifts just fine.

The basis:

• 2008 2500, 4x4, 3.73:1, 68RFE, 94k on the clock
• All fluids are proper levels (trans, diffs, x-fer, oil, PS)
• Oil is at 9k, Shell T6 - I have new stuff in the garage, working on getting to it (shouldn't matter)
• Fuel filter is at 14k, again almost near a swap (shouldn't matter here)
• Trans fluid was changed at 36k, so I guess I could be near a service there.
• Truck tows my 5er around, but since we moved to Tx I haven't been camping so its been 25k of no load.
• I was using a 40-70hp tune when unloaded for a while, stock when towing, but its been on stock hp for some time now, I just didn't need the power and MPG gain was negligible at best. Not worth it.

This morning I chalked the front tires and jacked up the rear end. I made a video and move the camera to different spots. It defiantly sounds like its form the trans area, not under the hood. The first rev is in Park, no noise. Then I moved it to drive and let the back wheels spin, it's very obvious when you hear it.

SCOTT6. GCROYLE has the right idea. I'm thinking the same because my '08 started with the sound of pots and pans
sheet metal rattle sound when cold that went away when warmed up. I also noticed a slight haze from the exhaust pipe
when moving out fast. It was a few months before a smog check in 2017. Hearing stories about cracked DPF media got me
paranoid, so I swapped out a new one and passed smog. The media didn't show any signs of damage and looked normal.
I still didn't know why it let out a haze. The haze went away with the new DPF. A year later the rattle came back along
with the haze. In 2019, smog check was coming up and did not change the DPF out but rather if it fails smog, then
replace. It passed smog with flying colors. I should have left the original DPF on the first time.
Thinking back when before the rattle started, I noticed the sound of petite backfires some times during heavy regens
when the exhaust brake is on and the throttle is just at coasting speed, in between slight accelerating and slight
exhaust braking. I here a "puck-puck" sound. I believe that the fuel saturated hot exhaust gases going down through the turbo and
DPF was actually doing a push pull from the turbo and has ignited causing a backfire and loosening up the filter media "can" inside
the DPF. This doesn't happen when the exhaust brake is off during heavy regen. So now I turn off the EB when in regen and turn
it back on when done. The rattle is still there when warming up but now I will leave the DPF alone until if the smog check fails.
Tommyturbo

 

[Scott6]

Well without going into details, im 100% sure its not my DPF of NOX. But I will be giving the CA extra attention tomorrow morning.

 

[Scott6]

Well, I got under it this morning with a stethoscope. I could hear the noise, but it didn’t seem to be coming from anywhere on the trans or the cat with the scope. (I guess that’s good)

I thought I heard it in the starter, but then it stoped shortly after getting there. Like I said before the noise seems to go away pretty quick after running, also my trans was getting hot (225* at the hot line out from power braking it) so let it cool in neutral and the noise has yet to come back. I did reload my tune to “stock power, off road only mode” sw0 just to be sure. Took it for a drive and really it runs perfectly fine, so IDK... spent some more time under inspecting and banging on stuff, nothing new to report.

 

[brucejohnson]

Well, I got under it this morning with a stethoscope. I could hear the noise, but it didn’t seem to be coming from anywhere on the trans or the cat with the scope. (I guess that’s good)

I thought I heard it in the starter, but then it stoped shortly after getting there. Like I said before the noise seems to go away pretty quick after running, also my trans was getting hot (225* at the hot line out from power braking it) so let it cool in neutral and the noise has yet to come back. I did reload my tune to “stock power, off road only mode” sw0 just to be sure. Took it for a drive and really it runs perfectly fine, so IDK... spent some more time under inspecting and banging on stuff, nothing new to report.

Maybe pull the starter and look at the return spring function? Doesn't quite sound like ones I have had that went bad...too tinny sounding; but this ain't no 60's beefed up small block FORD either. Still doesn't explain the trans mode forward gear element...Exhaust brake valve??? More video and audio needed. Still sounds exhaust related...or reciprocating mass area - fan, engine crank to trans input/flywheel.