Strange engine clicking noise no one can fix

[rootmanslim]

2001 4x4 auto trans engine is bone stock except for new injectors.
Truck has 98000 original miles
The noise reminds me of a loose tappet on an old solid lifter V8.
It only happens when truck is moving and engine under light load or coasting in gear.
Valves have been adjusted twice by different mechanics. Injectors were also changed to bigger ones.
We live @ 7200' and frequently go up to 10,000' towing 3000 pounds of horses and trailer. (even with the big Geno trans pan, the trans temp gets pretty high as we are only going 25 mph)
You can hear it very well with the windows open on either driver or passenger side.
I think it's something to do with the exhaust manifold or turbo but none of the diesel guys (we have a lot of MOPAR diesels in NW Wyoming) can seem to nail it down.
It's been going on at least 15K miles and doesn't get worse or better. As 01' are pretty noisy to start with, some people say it's just part of the package. My old 12 valve never made noises like this and had it been a 4X4 I wish I still had it.
Sometime soon the truck has to make a 5000 mile round trip towing those horses (happily mostly on the level) and I don't want to be biting my nails waiting to have to ride one of the horses to the nearest MOPAR truck fixer.
Thanks in advance.

 

[Tractorat]

I had my exhaust system replaced a couple of years ago. The first hanging bracket just under the door broke the weld and just sat there and rattled. Got it rewelded last year. Well, I heard the noise again the other day. Same weld broken again. I had to know where to look to find it. It doesnt move much. But if I put my finger on it while the engine is running, the noise goes away. I can wiggle it and just feel movement between the rod and the exhaust pipe.

 

[rootmanslim]

Thanks but this is in the engine compartment. The frequency of the clicks is directly tied to RPMs but does not happen at idle in park or under heavy load or serious acceleration. My exhaust is 100% original (no road salt or rain.)

 

[MARK JAQUITH]

My 01.5 has the same as you describe-- have 259000 miles--has been making that clicking sound since about 205000-never have been able to isolate the sound--hope someone
has an idea as I have checked or had checked everything--

Good Luck

Mark

 

[JR]

So it only happens while the truck is rolling, you can't reciprocate the noise when the truck is stationary and revving the engine. Are you absolutely sure it isn't a drivetrain noise? Universal joint? It seems to me if it was engine related it would not matter if the truck was rolling or not...

Are you familiar with Paradise Road in Boulder? I spent many summers on my grandparents ranch out there. I sure do miss it.

 

[rootmanslim]

Now up to 101,000 and it still does it. Be putting away in a month until June 19'. Out dealer now has a good mechanic so I'll probably turn it over to him come June for a complete review as 17 years is a while. He did one on my 05' Hemi Magnum AWD 133K miles and came up with a list to keep it going to 200K. About 4 grand worth --- lots cheaper than a new anything and truth be told there is nothing as good as that Magnum for WY to FL and back averaging illegal speeds.

 

[rootmanslim]

So it only happens while the truck is rolling, you can't reciprocate the noise when the truck is stationary and revving the engine. Are you absolutely sure it isn't a drivetrain noise? Universal joint? It seems to me if it was engine related it would not matter if the truck was rolling or not...

Are you familiar with Paradise Road in Boulder? I spent many summers on my grandparents ranch out there. I sure do miss it.

Doubt you would recognize it now. Wall to wall gas wells.

 

[AEdelheit]

Long shot but I would check the trans cooler hard lines, in park I dont think the 47RE flows oil through the cooler so if a clamp is slightly loose it could possibly only make noise in drive and there seems to more vibrations at low RPM so that could be why it goes away with a load. Hard to believe it would make a loud enough noise to hear over a 24V but never know.

 

[KATOOM]

I'm guessing the noise you're hearing changes tone or pace depending on the engine RPM...?

 

[Joe Mc]

AEdelheit has a good point. While under mine some time back I noticed the plastic factory clips that secure the lines together and to an oil pan stud broken and looked more towards trans and on both sides of engine and between engine and trans. Anywhere they were close or touching I spiral sliced some rubber hose and slid it between the lines securing with wire ties. Mine wasn't making any noise but lines rubbing together usually end up with a hole...