Troubleshooting weird rattling noise in engine bay

DieselJeepLuvr · **Posted:** Tue Nov 21, 2017 11:55 pm

I have had a rattling sound on cold starts that has been getting worse (started several weeks ago) I have put probably 1500 miles on it since first noticing it. Once the engine warms up I don't hear it any more and I can't hear it inside just when I stick my head by the radiator or especially when I open the hood. Today I took it to the local dealer and they had a couple mechanics on it with a stethoscope checking things out. They were able to access a portion of stuff inside the timing belt area. They weren't able to nail down a location but one mechanic said it was louder on the turbo housing bracket then any where else. They eventually decided that it's internal in the engine and I should trade it in... or something (probably didn't help I was eyeing their hellcat challenger). I just had an oil sample come back clean so I'm thinking it's got to be something timing belt driven (hopefully) Weird thing is once it's warmed up it purrs like a kitten. Could it be a bad glow plug or something? Reason I bring that up is I have no glow plug light that comes on so either the bulb is burned out or someone before me deleted it???

Thoughts?

GordnadoCRD · **Posted:** Wed Nov 22, 2017 4:18 am

The glow plug light when working properly, goes out almost immediately when you turn the key on, even if it's very cold.
A bad glow plug can cause a hard knocking until that cylinder gets warmed.
It could also be a collapsed or sticking hydraulic valve adjuster that takes time to pump up.
Have you looked at the serpentine belt tensioner? It's a hail Mary guess because I can't see that one going away with temperature, without hearing it though, I can do no better than guess.

Edit: The good news, though, is a main or rod bearing would get more pronounced as it warms up.

WWDiesel · **Posted:** Wed Nov 22, 2017 2:27 pm

Check the harmonic balancer; there have been several of them as of late that have been found coming apart where the rubber is bonded to the metal... :roll:

DieselJeepLuvr · **Posted:** Thu Nov 23, 2017 1:09 pm

Glow plug light never comes on even for a second. If a glow plug is bad won't it throw a CEL? I have none. This weekend I'll start looking at things driven by the timing belt and check out the harmonic balancer too but that doesn't seem like it would cause the sound I'm hearing unless it was about to fall off. I'll keep everyone informed... Thanks for the help!

flash7210 · **Posted:** Thu Nov 23, 2017 1:45 pm

Remove the serpentine belt then start the engine to see if the noise goes away.

If you had a glow plug problem a code would be set.
Does you CEL work?
Have you scanned for codes?

Sergio del Castillo · **Posted:** Fri Nov 24, 2017 12:40 pm

I confronted the same type of noise about a year ago.

The technician removed the serpentine belt and run the engine for a while, the noise was still there. Them we removed the timing belt, was due for a replacement anyhow, and discovered two items at fault. One was the water pump, the bearing was gone and the impeller was rubbing the housing, even though it did not leaked, and the second was the harmonic balancer, the rubber had disintegrated in several places and was wobbling. Replaced the timing belt, idler pulleys, tension puller, the water pump and the harmonic balancer and the noise was gone.

DieselJeepLuvr · **Posted:** Wed Nov 29, 2017 12:27 am

update: This morning was 35 F so I plugged it in last night to see if I could hear it when I first started it (yup). Yes the glow plug light DOES work. Unless you are staring at it the instant you turn the key you will miss it (crazy fast flash) Drove it to full operating temp and I could still hear the rattle. After it cooled down I weaseled my arm down to the vibration dampener and with great difficulty go my finger tip down there and (I think) felt movement. So... I will be replacing this part for sure. Good thing I didn't listen when the dealership said "Looks like it's time to trade er' in..." I was one click away from ordering a new Cummins R2.8 for this bad boy! The hell with those stupid VM's! :JEEPIN:

carbcoma · **Joined:** Sat Oct 01, 2016 9:48 pm **Posts:** 86

what would u guess total cost of swapping in cummins 2.8?

Sir Sam · **Posted:** Sat Dec 09, 2017 12:58 am

carbcoma wrote:

what would u guess total cost of swapping in cummins 2.8?

Probably about as much as buying 2 running and driving CRDs.

DieselJeepLuvr · **Posted:** Wed Dec 20, 2017 12:12 am

Update:

it WAS the vibration dampener! Thanks WW and Sergio for the heads up. it was about to fall apart. This should be something that should be done after 100k during a serpentine belt change. Huge PITA if that's the only thing you need to do. Sometimes I miss the days when you could sit on the inner fenderwell of a vehicle to give it a tuneup...

As for the Cummins R2.8 I've sent several requests to them to sell this motor with plug and play capabilities for our Libbies. No luck yet. From a marketing standpoint it makes no sense to seek custom builders of offroad jeeps when you already have a huge market base of diesel lovers here. All you need is an engine that takes the same adapter plate as the VM to 545 RFE and some interchangable electrical plugs for the injectors, rail, crank position sensor etc. I haven't done any research yet to verify but I think the rail pressures are comparable. Then all you are modifying is the intake filter assembly, exhaust and maybe motor mounts. Cummins won't need to provide all the peripherals that come with it BAM! Now that would sell !!! I would think they'd be able to sell this for the same price or less. The liberty platform is an excellent platform for longevity if they got rid of the stupid VM. Even the newer 3.0 Echodiesel is a POS (They are great until they blow up...) As for the cost of the upgrade... It would be money in the bank. Cummins powered vehicles retain value like no other modern vehicles.

craws010 · **Posted:** Wed Dec 20, 2017 12:23 am

DieselJeepLuvr wrote:

Update:

it WAS the vibration dampener! Thanks WW and Sergio for the heads up. it was about to fall apart. This should be something that should be done after 100k during a serpentine belt change. Huge PITA if that's the only thing you need to do. Sometimes I miss the days when you could sit on the inner fenderwell of a vehicle to give it a tuneup...

I am planning to tackle the dampener job tomorrow. Did you have to pull the radiator, shroud and intercooler?

Troubleshooting weird rattling noise in engine bay

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