2005 Tundra with engine rattle

My Tundra when first started is quiet until it has run 5-6 minutes then it develops a slight rattle while at idle, it sounds almost like a marble rolling around. When put into drive it quits, taken up to highway speeds for 10 or so minutes and then back to park the rattle is louder, it is coming from the back of the engine, place it back into drive & it stops or is much quieter, it is not an exhaust leak or tappets.
I have a friend who is a certified and 20 year Toyota mechanic tell me he has never heard anything quite like this. We have placed it up on a hoist started it and could not pinpoint where it's coming from but certainly the back of the engine. The Motor is a 4.7 original to the truck & runs great, doesn't use oil and this problem has been going on for the past 5 weeks or so, slowly getting a little louder. It does have 300K
all road miles and no past issues.
Any suggestions?

 

Torque converter? Loose bolt? Doesn’t sound like it. Rattle sounds more like exhaust shield, but surely a 20yr certified Toyota mechanic could spot that a mile away.

 

Its 4WD so I suppose it's not the tranny mount issue the 2WD trucks had a TSB on ....

 

We checked the exhaust shields before , the problem is it's not a loose rattle, more mechanical clicking type of noise. It gets louder when giving it gas while in park, stop's when in drive or barely noticeable.
I have drained the oil out to check for any metal filings in the oil, clean. The motor performs as normal, no power loss, smoking,ect. again it doesn't do anything until the motor has been run 10 minutes or so and then it's a gradual increase. After a 20 mile drive at this point it's still not very loud but it has increased but barely audible in the car, Stopping at a intersection. then the noise is much louder but when taking off up to highway speed again can hardly hear it.
I hope this makes sense

 

I'm not saying this is your issue, but I remember this one time I was super pissed because I had this CLUNK that would only happen on certain turns. Anytime I was on washboard roads, an extra CLACKETY CLACKETY sound which seemed like it was coming from the dash. I literally gutted everything in any storage area of the truck, from the glovebox downward, including the ash tray, just to make sure it wasn't something stored. Ripped the rear seat out and its seatbelts. Passenger seat and seatbelt, rear jack assembly bolted into the chassis. Only thing left in the truck at this point were the headliner, driver seat, and seat belt. Even took out the glovebox door.

Pissed, I leave everything out for a few weeks and drive around like normal. Then, one day, I'm driving west into the sun, and reach up to the overhead console to grab my sunglasses .... "uh, shit" ... I totally forgot two things: One, I didn't have my sunglasses in the truck, they were in the boat. Two, I had a mini flashlight in the sunglass holder which was making the CLUNK sliding back and forth in the sunglass compartment every time I turned, and the CLACKETY CLACKETY on washboard roads.

Anyway, this whole rant to say, it sucks when you can't find noises and sometimes it's in the stupidest place possible you forgot existed. I think the best thing you can do is to get someone to help go through the motions while you're outside the truck with the hood open, try figure out whether it's inside or outside, if outside, is it under the hood, in or under the truck, etc.

 

Thanks Shifty, I spent 30 years of my life in new car dealerships body shops & doing just that, chasing rattles, wind-noise, ect . I've done the same thing to my truck and found that the noise is coming from the rear of the engine and with my mechanic friend, also putting it up on a hoist that I mentioned earlier while it was running.
Don't get me wrong this isn't my first rodeo & defiantly appreciate any and all input, but as you said, it really sucks, I like my truck & being a bit bull headed will not give up until I find it.
I'm hoping that someone out there may have had something similar to my problem, I know there's no magic involved, after all it is man made there is a cure.

 

I wonder if it might be a cracked flex plate.

Check this out.

https://forum.ih8mud.com/threads/do-you-have-a-strange-knocking-at-idle.1003033/

 

Thanks Landphil, I checked that thread out & I'm sure they have something defiantly worth exploring further. They described the sound that I'm hearing plus it's seems to be coming from the back of the engine bell housing area.
This frigid weather makes it harder to get it in right now but will asap, don't want to do any more damage than what has been done.


Thanks again Landphil, I owe you a case of Good Beer. Thanks to that thread you sent we just pulled the tranny & replaced the Flex Plate, mine was definitely cracked and very Lucky it didn't take out the Tranny & Bell Housing.
I would send pictures but haven't figured out to respond to your post, so I hope you see this.
Red Squirel

 

Thanks again Landphil, I owe you a case of Good Beer. Thanks to the thread you sent me with the info that sounded just like my problem and the cure was to replace the Flex Plate, Who would have thought that would be the cure.
We removed the Flex Plate and Holy Crap, I was very lucky it didn't blow apart, it was cracked almost 2/3 of the way around the mounting area. I just uploaded the file pics of the flex plate and hope it comes thru.

Thanks again
Red Squirel

 

Glad you got it figured out. Helping with a picture assist so folks won't need to download the zip file.

(PS - HOLY SHIT!)

 

Hey @Red Squirel when this started, I assume it was a much lighter sounding click? Did the symptoms ever sound anything like the video in this thread, where another member was asking about a clicking noise?

https://www.tundras.com/threads/clicking-noise-from-engine-or-belts.102057/

 

Wow, that's crazy. Thanks for coming back to share what the actual issue was and your remedy.

 

Whoohoo. Mystery solved. A bit of work, but not the worst job.

Were you able to see the cracks before removing the transmission?

 

Wow! Thanks for the follow-up Red Squirel. I guess from the yellow paint dot we can infer this was the original OEM flex plate. It made it 300k miles but still kinda spooky it would fatigue and fail like that. Glad you got it fixed before it detonated inside the housing. On another note, I'g guessing 300k on the original transmission? Toyota for the win!