I have a strange sound, like a chain or slinky rattling when the truck is idling. Sounds like it is coming from the center of the engine, maybe the fan clutch. Anyone ever heard this and how can I fix it. Thanks

 

I can't believe someone has not heard of this problem or has some comment

 

I had the heat shield rattling right under the cab of the truck. It would do it only when you closed the door. I noticed that some of push tabs thingys were gone. I made my own and no more rattling.

 

Check the clamps that hold the fuel lines that go to the injectors. I had one that came loose and the rattling sounded a light duty chain rattling. They are on the top of the engine by the valve cover on the drivers’ side.

 

Detonation...check for gasoline in the fuel

 

thanks for the response. It is not the heat shield or the fuel line clamps. or detonation. The noise is definately right in the front/middle of the engine. Sounds like it is the fan clutch or other tensioner pulley

 

05 diesel, doolie, not gasoline

 

Take off your serp belt and see if it quits. Might narrow it down.

An AC clutch can rattle and ring.

 

sometimes the gear on the inj pump makes a ringing type noise, cummins says its harmonics. you can rotate the gear qtr turn & maybe it will go away

 

Thats why I said check for gasoline in YOUR diesel fuel.Sometimes gas gets mixed in the diesel - gasoline burns quicker than diesel,causes detonation,which would be the chain like noise,but it would probably run like crap

 

I always thought diesel caused gasoline motors to detonate as it would fire from the compression before reaching tdc. Dont think it can cause detonation in a diesel as it cant get into the cylinder till a few degrees before tdc.

 

Yeap, sounds as if it is the CP3 gear rattle that you will hear from time to time, especially when cold. Go work the truck and it will go away.

 

FYI. I got the chain sound diagnosed and fixed. It was the fan clutch support assembly. $500. The bolt that went through the bearing and connected the fan clutch broke and the bearings were rattling and about to come apart.

 

Also, why start with an extreme. start with simple stuff. It can be an exhaust bracket.

 

DANG!! I just saw this and was going to say check the fan clutch bolt....


And diesel making a gas engine pre-detonate??

Gasoline is much more volatile than diesel. Putting diesel in a gas engine makes the engine extremely quiet.