Having trouble ID rattle noise.

[Hewy]

Here is the story. While driving a low speeds 45 mph and below, everything sounds good. Good power no sounds other than
the engine humming away.
Hit a few small road bumps and can identify some suspension fender harmonic sounds, at least I think it is.
The engine sounds good even hard acceleration up or down hills.
Here is where the noise that concerns me comes on. At around 50 particularly on a slight incline
the rattle sound starts . Let off the gas pedal and it disappears, back on even just a little the rattle starts again.
My imagination kicks in with " the engine moves and loads the drive train and the rear springs hit the over loads" "The flywheel is loose" The shock tubes rattle"
or worst of all the "valves are coming apart" " piston slapping"
I do know this, the clutch does need attention and probably the rear shocks need to be replaced.
The spring sets are stock 5 leaf front, 6 leaf with overload on top of pack at the rear.3 speed manual trans and a 318 poly.
Any one experience this ?????

[wally426ci]

Could it be "Pinging"?

I do the same. Panic kicks into worst case scenario.

[Hobcobble]

Is your drive shaft clocked?
John

[PwrWgnDrvr]

U-jts do wierd stuff like that before they self destruct.
Or, u can simplify use the tried and true method of "drive it til it breaks, then fix it.)

[dodgeboykim]

Or, u can simplify use the tried and true method of "drive it til it breaks, then fix it.)

That works

[Jims68]

U-jts do wierd stuff like that before they self destruct.
Or, u can simplify use the tried and true method of "drive it til it breaks, then fix it.)

Yeah but... they never break in your driveway!

That is my method. I usually won't fix it till it's broke. All that said, and kidding aside of course if I do see something wrong, I fix it! Sometimes those little klinks and knocks will drive ya crazy!

Jim

[PwrWgnDrvr]

Yeah but... they never break in your driveway!
Jim

That's half the fun - variety, the spice of life - like, rolling the W300 backwards out of the Caldecott tunnel against rush hr traffic cuz there's no shoulder and u cant coast a half mile UPhill!

[Hewy]

No ping just a very distinct rattle like a loose bunch of bolts , then I can push the clutch in rev
the engine and the noise is gone.
I thought of driving till something breaks, yuk. One big reason I stay off the freeways.
I guess it is a process of elimination, wonder how the truck will handle with out shocks.
Drive shaft ujoints will be inspected that is a good place to start.

[StinkFinger]

Drive shaft u joints or clutch disk springs would be my guess

[PwrWgnDrvr]

Easy check for uj's is to get in a cold truck, drive 2-3 miles, then touch each uj cup bearing. If it is dry and failing it will be much hotter than any others. Careful, sometimes hot enough to burn the hell out of u. If u drive farther than that, good cups can heat up enough that they are about the same as a bad one.
On rare occasion, they wont heat up, they wont have side play, they just seem fine, til they break. Only way to check for absolute certainty is to take the damn things out and visually inspect.

[Txas2step]

Hewy, are you sure it's not octane rattle under a load? Are you running the higher octane gas or additive? have you checked the timing? Chris.

[712edf]

How are the motor mounts? Could motor be moving enough under load to be causing misalignment of drivetrain, or maybe fan to hit shroud?
Bucky

[Hewy]

How are the motor mounts? Could motor be moving enough under load to be causing misalignment of drivetrain, or maybe fan to hit shroud?
Bucky

Hewy, are you sure it's not octane rattle under a load? Are you running the higher octane gas or additive? have you checked the timing? Chris.

Don't think it's octane related, pulls fine no noise till moving around 50 + even when not accelerating.
More related to vehicle movement as in suspension action at the higher speed or the drive shaft and/or clutch. Almost as if something
is loose.

[nytemuvr]

Yeah but... they never break in your driveway! :lol:
Jim

That's half the fun - variety, the spice of life - like, rolling the W300 backwards out of the Caldecott tunnel against rush hr traffic cuz there's no shoulder and u cant coast a half mile UPhill! :lol:

The Caldecott high speed test track....130 mph in my Challenger, open headers....lovely sound. Getting away from a bunch of guys in a van tossin water balloons at me.
Sounds like driveline may be bent.

[wally426ci]

Mine has a metallic rattle that I can't place either. It's around the same point in 4th gear. It almost sounds like it's in the trans.

I have not figure it out.

[surfnuke9]

seems to me that if it only happens at 50 mph and not at lower speeds with the same engine rpm, this would seem to eliminate clutch or throwout bearing as the cause and lead more towards a driveline or final gear set in the transmission issue.

[nytemuvr]

I don't have a rattle noise except the windows (need new felts), but it may be your fan if it doesn't have a clutch. Mine makes a noise at 40-45 mph without a fan clutch, that's about where it hits a harmonic noise that's rattle-like, like all old cars pre-fan clutch days.

[Hewy]

seems to me that if it only happens at 50 mph and not at lower speeds with the same engine rpm, this would seem to eliminate clutch or throwout bearing as the cause and lead more towards a driveline or final gear set in the transmission issue.

This seems to be closer to what it might be, it began last time I pulled my travel trailer and intensifies when loading the drive line in high gear.
What I mean by loading the drive line, is to maintain momentum you accelerate slightly that's when the sound is loudest, back off a little and sound goes away.
I am planning on doing a clutch job, so will look at the transmission when it is out. Until then I am driving easy.

[wally426ci]

How would one go about getting the gears set again? I think this is my same issue. After I pulled the top cover and forks, it started.

[Hewy]

Update.........
As I learned many moons ago, I approached the problem by the elimination process
called KISS.
Uhmmm so started with shocks they looked old, but not original to the truck.
The rears came off first, left one collapsed by hand like empty tubes. Oh my vast expertise came into
play worn out Right one came off it was little stiffer, but not much resistance when collapsing by hand.
OK Mister expert mechanic I sez to myself, figure that one out.
Go take the fronts off. Lot stiffer but the right one was weaker than the left.
Here is the conclusion to this mysterious drama, go buy some 4 new Monroes $125 later and installed.
Rattles gone. BEER time.