The rattle mystery....

Sup guys.

1995 Taco 3RZ W59 4x4 Manual

A lot of info here so please read all of it before replying. I know sometimes people read half and suggest something the OP has already done LOL (i've done it myself).

Been having this issue with a rattle/scrapy sound coming from under the truck. Been chasing it for 3 years now.

It's a rattle that sounds more like a heat shield/metal scraping..based on engine rpm. Press clutch and let go of the throttle and it goes away, clutch still pressed you give it some gas and it is pretty loud past 1800 rpm and it's...only when moving (driveshaft spinning). No clearance issues no moving parts hitting anything.

I have recreated it ever so faintly when the driveshaft wasn't spinning at a certain rpm and put my hand on the driveshaft and it went away. Gear doesn't matter.

I can press the clutch in and give it gas when I'm moving and it's horrid. The worst is when it's under 1st, 2nd, or 3rd gear load.

What I have done since it started:

1) Replaced the driveshaft and upgraded it with all new spicer stuff (got a used shaft, cut the double cardan off and had a new one welded on new u joints etc...)

Driveshaft Story: Dealer and 2 driveline shops looked at it.

-Dealer inspected took the shaft off etc.. and determined it was the double cardan joint.

-1st shop replaced the double cardan u joints and ball and rear u joint. (rebuilt it)

Noise came back after 2 months.

Warrantied it out and they did the job again.

Noise came back again after 2 months.

-2nd shop replaced the assembly completely (got used shaft and they put on a spicer set-up)

Noise came back after 2 months.

2) I have replaced the T-case

3) I have rebuilt my trans (all new bearings, syncros etc...)

4) All new clutch, pilot, throw-out bearings, fork, pivot, master, slave cyl.....

5) I have replaced the engine (not that it's relevant but I am rebuilding the original).

6) Replaced entire exhaust from the head back. (all heatshields are good and checked).

So basically I have a completely new drive-line. STILL making that noise.

The only thing I'm thinking it could be at this point since the sound is literally coming from the driveshaft is the rear end pinion bearing perhaps (has very slight play when sitting still) could be resonating through the driveshaft acting like a bell. IDK I am lost.

I noticed that the noise goes away and comes back after the driveshaft is removed and re-installed. I have unbolted the driveshaft for something else and bolted it back on and the noise went away...then came back after a month. Something that has to do with the pre-load I think when it is bolted on and once everything settles it comes back.

Very strange.

Thoughts?

 

Buy a chassis ear setup and try and pinpoint the noise.

$101 Steelman ChassisEAR Automotive Diagnostics Multichannel Electronic Stethoscope Tool, 6 Noise-Finder Microphone Clamps with Leads, Over-Ear Headphones

STEELMAN 06600 ChassisEAR Stethoscope

Parking brake lever and cables aren't loose?
Sounds like a tough one to diagnose. Gremlins?

 

Parking brake lever and cables are in good order. I will double check however.

That chassis ear setup is a great idea. I do a lot of repair work for about 10 years and this is one of the first ones to ever stump me...on my own vehicle lol

I can use it in the future for other things....$220 bucks for the wireless one tho damn...

And as far as gremlins go....with my luck yea. It's an odd gremlin. I have one with my A/C system as well. Ac wouldnt work. I then replaced the entire system and I ended up having to bypass the ECU (after testing 3 different ECU's) just to get the A/C to work. So this is gremlin #2 lol

Thanks for the quick response

 

I have the one i listed a link to. Had it about 20 years. One of they best tools hands down for finding noises.

 

Just ordered the wireless one. I hate dealing with wires. Watched some Youtube demonstrations and it looked like it worked well.

If it doesn't work well Ill just return it get the wired one. we shall see. Should be here tomorrow.


And BTW since we are sharing tool info...I found an amazing tool for Coolant system bleeding, filling, and checking for leaks a couple weeks ago. Takes no time at all less than 100 bucks.

https://www.ecstuning.com/b-schwaben-parts/coolant-refill-air-purge-tool/003466sch01/

Universal but on BMW especially the best tool instead of bleeding for an hour.

Just sharing

 

Well... If it were mine. I'd take a large hose clamp or two, and some rubber "Dampening" material. Strap that to the drive shaft and see if the noise goes away.
I realize this will make the drive line out of balance. But it should cancel any noise.
you might want to check gas tank straps/shields for rattle.

Related; I had a 98 Toyota pickup that had a rattle. Turned out I had bent the forward edge of the bed. It was touching the cab, creating a rattle.

 

Are you referring to temporarily to just diagnose it?

 

Yes, just temporary.

 

You could even move the test clamps up and down the length of the drive shaft.

 

I have removed and reinstalled the gas tank and replaced the dampening material around the tank/straps due to a fuel pump failure 5K miles ago so not that unfortunately.

I can see the forward edge creating a rattle but it's more of a ting than a buzz if you know what a mean.

 

I will see what I can do about mounting the test clamps when I get the tool. I should have it by tomorrow (1 day ship) so we will see.

 

Do you have any spare parts or tools in the compartment behind the seats? Maybe a loose socket got loose?

 

Nah. Regardless of what is behind the seat It is coming from under the cab 100%

When I sit in traffic and start to speed up say and I am in the left lane on the highway with a concrete median and have the window rolled down it sounds nasty as the sound is bouncing off the median you know what I mean?

 

When you say this, along with a raspy/scrapy sound...it makes me think of a bad wheel bearing. Would you describe it as a grinding sound, too?

Easy to check if it's the wheel bearing, jack the tires up and spin them to see if you can replicate the sound. Also check for play in the wheels (try moving them up/down/side to side)

edit: I missed the part about the sound being related to the clutch...which to me sounds like a throwout bearing issue, but you said that's been replaced so maybe not. I had a bad TOB chirp that went away once I replaced it with a new clutch but it came right back a few thousand miles later. TOBs on these trucks are notorious for making noise. Mine still does it; sounds like angry crickets.

 

I Know what you mean, however, I have had it up on all four jack stands in 2WD and 4WD engine on accelerating going through the gears as if I am driving wheels spinning while I am laying down under it (buddy helped obv.) and it is loudest directly under the driveshaft and there is no noise from the wheels. All wheels spin freely if I do so by hand and no noise or resistance.

And in neutral it almost doesn't do it at all theres a VERY fine area where there is a light rattle at 1850 and it goes away after that but it seems like the driveshaft has to be spinning.

 

Not related to the clutch at all! What I meant was I am riding down the highway and put it in neutral and it will do the same thing. I just referred to pressing the clutch as in taking the load off the transmission but still being in gear and it rattles in every gear when I am moving regardless of being under a load or not just revving the engine creates the noise if the driveshaft is spinning. It's like the engine vibrations is causing something to rattle/scrape when the driveshaft is spinning. And extra loud when under a load.

 

Lol I know members have MOD days here depending on state we should have a "Gremlin Day" where we get together like Mod day in a garage and everyone pitches in helping each other solve each other's gremlins

 

well color me stumped, I'll remain subbed to hopefully see a solution in case something similar happens to me lol.

 

Also if you can, try to post a video with sound of the location and noise...might help someone here narrow it down

 

Tomorrow I'm gonna put it up on all 4 jackstands again and see if I can re create it in the garage again and take a video. Hopefully I can capture it.