Engine/Transmission (1998.5 - 2002) Strange Sound

[Hobart]

I've got a rythmic clanging coming from the engine. A ching,ching, ching. Like beating on metal. Loud if I'm under the pan; hardly noticable standing beside the truck. Also I seem to hear it in the cab at around 1500rps under load. Can't hear it above 1700rpms or below 1400.

Thought it might be valves - checked them and they're ok. And like i said loudest under the pan. Actually been going on a long time. I just noticed particularly today parked against a retaining wall which reflected the sound.
Could it be the timing chain rattling?

 

[ILIANBG]

There is no timing chain in these trucks, just gears under that cover in the front of the engine. Have it diagnosed before it is too expensive to fix.

 

[AKAMAC]

I know it's a long shot, but...

Inspect your exhaust system. Especially the hanger next to the transmission and the clamp at the turbo. My MBRB 4" hanger pulled loose and did that noise at those RPMs. I hope that solves your problem.

 

[Hobart]

Well I went over the engine with a hose to my ear. Sound is not from anything like valves,pistons etc. Most of the clacking diesel noise comes from the back between the engine and transmission.

 

[WoosterDiesel]

Does it do it when it's in 4 wheel drive as well? I would try that, and try to decipher from your transfer case, or the transmission, or the engine.

 

[AKAMAC]

Pull the inspection pan under the T/C and check your flex plate and bolts.

 

[MCummings]

Seen this noise alot with broken flexplates...



Merrick

 

[Hobart]

Will do. But what is a flex plate - any photos?

 

[AKAMAC]

Connects the T/C to engine and has the starter ring gear.

 

[MCummings]

Flexplate is the automatics' version of a flywheel...



Merrick

 

[Hobart]

So how do I tell if there is a problem with it?

 

[MCummings]

I've got a rythmic clanging coming from the engine. A ching,ching, ching. Like beating on metal. Loud if I'm under the pan; hardly noticable standing beside the truck. Also I seem to hear it in the cab at around 1500rps under load. Can't hear it above 1700rpms or below 1400.

That's generally how you tell. :-laf

Exhaust all your other options, then drop the trans.

Make sure the TC bolts are tight before you drop the trans as it could just be the TC bolts that are loose.....

Merrick

 

[Hobart]

Removed the inspection plate. Looks OK; no metal or cracks; TC bolts tight.

 

[AKAMAC]

Did you look at the exhaust hanger next to the transmission? It is a 1/2" bar welded to the exhaust and supported by a rubber mount on the frame.