Engine knock at idle???

[Nugentmechanicservices]

I have a customer that has recently bought a 2005 ram with a 5.9l Cummins and he called me saying the engine has a rattle. Well I got to his place Checked the truck out and sure enough the engine has an intermittent knock at idle. When you accelerate the rpm’s the engine quits knocking. Is there anyone that maybe help me out. Maybe it’s a fuel knock or it could be worse . Any help would be greatly appreciated.

 

[Signal73]

Going to need to do a injector cut out test for starters.

 

[Nugentmechanicservices]

I agree 100% that’s my next move. Is there a way to upload a video of it running on here?

 

[Ozymandias]

Use Youtube and embeed a link to it in your next post.

 

[Tuesdak]

Check the oil pressure with a mechanical gauge. I have had the pressure valves in the oil cooler (oil filter) area rattle returning to idle due to low oil pressure.

How many miles on the injectors? Factory filtration? Fuel smell like gasoline or other quality problems? Engine oil condition including diesel fuel contamination is a possibility to do a UOA for. Keep and inspect the oil filter in case it came apart internally. Do Not Cut Open as this may affect the filter OEM from covering the engine if the filter came apart.

 

[Nugentmechanicservices]

https://youtube.com/shorts/FmK3XBWOI_o?si=9oZ3qG3TYDWhaaRW

 

[Nugentmechanicservices]

I just uploaded a link on here as soon as it gets approved you should be able to click the link to my YouTube video of the engine running if y’all could take a quick listen and tell me what you think that would be awesome.

 

[Nugentmechanicservices]

I will also definitely also check the oil pressure when I go back to work on the truck. This is a little history about the truck. So the owner was told that the engine had just had a fresh rebuild on it. Now just from going through the engine routine maintenance. I found the water pump was leaking a small bit out the weep hole so I changed it and the turbo was under boost the actuator on the turbo was froze up and not working so the owner had me put a new turbo on. the engine has new freeze plugs through out, new oil pan gasket, or at least it’s been taken off recently by someone else because they used ultra black silicone on the seams doesn’t at all look factory. The exhaust manifold is newer. Just to name a few things I caught going over it. I guess im just wondering if someone did “freshen” up this engine did they not torque the rod caps right or maybe a wrist pin is lose. This I’m not sure of having not opened it up as of yet. I want to exhaust every possible test before I dive deeper don’t want my customer to pay for a service he doesn’t need you know.

 

[Nugentmechanicservices]

Check the oil pressure with a mechanical gauge. I have had the pressure valves in the oil cooler (oil filter) area rattle returning to idle due to low oil pressure.

How many miles on the injectors? Factory filtration? Fuel smell like gasoline or other quality problems? Engine oil condition including diesel fuel contamination is a possibility to do a UOA for. Keep and inspect the oil filter in case it came apart internally. Do Not Cut Open as this may affect the filter OEM from covering the engine if the filter came apart.

As far as I know the truck has around 270000 miles on it. I’m not sure if the injectors have ever been changed. But I did leave a brief description of the history I do know about it. Also I drained the oil and the oil filter which is all stock. All the filtration is OEM nothing aftermarket. Didn’t see any metal flake or shimmer. Fuel smells fine looks clean also I changed the filters just to be sure.

 

[Ozymandias]

Take an oil sample and have it tested.

 

[Killer223]

That doesn't sound like a knock to me. take the belt off, and check the flywheel bolts for torque.

 

[AH64ID]

That doesn't sound like a knock to me. take the belt off, and check the flywheel bolts for torque.

Definitely not an internal knock, something is loose/broken.

 

[sag2]

Cracked flex plate?

 

[bcbender]

That doesn't sound like a knock to me. take the belt off, and check the flywheel bolts for torque.

X2 take the belt off. Could be a failing bearing on an accessory also, sometime (1) ball can stick intermittently and make a clack/tick sound. If goes away with belt off you know its in the front somewhere, if not, its in the back.

 

[Nugentmechanicservices]

Cracked flex plate?[/QUOTE
Thats exactly what I’m thinking.

 

[Nugentmechanicservices]

Ok so after finally being able to get back to the truck I’ve checked all the torque converter bolts and pulling the drive belt off to check for any change in the noise. I noticed that when I put it in gear the noise quits and when I put it back in neutral it starts to rattle again so I’m definitely thinking the flex plate is cracked.