Rattling noise at idle

WWDiesel · **Posted:** Wed Jan 28, 2015 11:03 pm

Have you ran the engine with the serpentine belt removed to see if the noise goes away?
Is your serpentine belt tensioner pulley vibrating or jumping up and down at idle?
If either of the above statements are true, replace the alternator decoupler.
Just been there and done that this week. Mine was locked up and only rattled at idle! Worse with AC on :roll:

Amazing how much difference it made at idle... :wink:

Read this topic:
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=81214

remwines · **Posted:** Thu Jan 29, 2015 11:37 am

I planned to take the serpentine belt off today just to rule out anything in that system. The belt and all pulleys and tensioners are running true and smooth. The rattle is no different with the air conditioning compressor engaged or when putting a load on the power steering pump. It does rattle a bit less after the engine has reached operating temperature. I would be very happy if it were the alternator decoupler. Was there powdered rust on your decoupler? I recently had to put a new alternator on my TDI Jetta because of a decoupler failure. The center of the decoupler was covered with powdered rust.

remwines · **Posted:** Sat Jan 31, 2015 11:25 am

It still rattles after taking the serpentine belt off. So I guess I will tear into timing belt cover and hope I find something simple that has failed.

WWDiesel · **Posted:** Sat Jan 31, 2015 12:53 pm

Is the noise at the front or rear of the motor? Some have had the torque converter bolt come loose and rattle at idle. They can be accessed by removing the starter I believe and checking their torque one at a time by manually rotating the engine. :idea:

geordi · **Posted:** Sat Jan 31, 2015 1:07 pm

Not the worst to pull the front cover for an inspection tour, that should take maybe 45 minutes if you go slow. You definitely want to chase this down, it would be unfortunate if it caused another failure. I'm surprised you haven't located it yet though, most rattles tend to be in the driveline somewhere, or a sound short to the body.

Does it change if you put the transmission in drive or reverse and hold the brake? That would load the driveline and shift the engine around. I know you said you replaced the engine mounts... What about the mount under the transmission? Did you try shoving a rubber pad into that, maybe a rubber doorstop just as a test?

remwines · **Posted:** Sat Jan 31, 2015 3:02 pm

I have tried all means to see if anything would make a changes in the rattle, trans fwd/rvs under load, air on/off, power steering loaded, new oem engine mounts, etc. The only things that changes the rattle is to increase RPMs to over 1200, and the rattle will slightly decreases after the engine warms to operating temperature. With the Jeep on the rack, serpentine belt off, engine running, and factory skid plate off, the rattle is definitely in the area of the vibration dampener. I could not find any metal to metal rubs. I didn't know it was possible to inspect the timing belt assembly, so I will try to pull the front cover off enough to see if anything is damaged.

JoeStretch · **Posted:** Sat Jan 31, 2015 11:47 pm

Does it sound like this? http://youtu.be/DclMo04EGLM.

i had this noise crop up when the engine is cold and goes away once warm. Took it to a mechanic and had water pump, timing belt , tb tensioners and idler pulleys replaced. Still makes the noise. The mechanic noticed some notches taken out of the harmonic balancer and said we should try to replace it.

geordi · **Posted:** Sun Feb 01, 2015 3:25 am

You need to pull the balancer off in order to inspect the timing anyway - Look at the back of it, it is easy to get to (once the fan and shroud are out of the way)... If the rubber ring is missing chunks or possibly not really even there - The balancer could be the problem. I've heard of a few people that have had issues with that thing, although for the life of me I can't understand why or how it happens.

remwines · **Posted:** Tue Feb 03, 2015 12:02 pm

JoeStretch: That is the rattle! Sorry for the slow response. I tried to respond right after you posted the video, but I guess it did go through. I will start working my way down to the balancer tomorrow. Sure hope that's it. It is exactly like your video. Thanks much for posting it.

JoeStretch · **Posted:** Tue Feb 03, 2015 2:31 pm

Mine has gotten really loud the last few days, get your serpentine belt off and if it still makes that noise you might inspect the harmonic balancer. Has anyone replaced their harmonic balancer? Best place to buy one?

JoeStretch · **Posted:** Tue Feb 03, 2015 7:41 pm

Still not sure why the noise goes away when the engine gets hot? I understand that metal expands when it is
hot but I thought that the harmonic balancer was part rubber? Maybe the rubber is acting the same way?

remwines · **Posted:** Wed Feb 04, 2015 10:29 am

Mine still rattles after it warms up, just less. The balancer is referred to as a crankshaft pulley on the Mopar parts sites and is Part Number: 5072669AA. AllMoparParts.com has them for $100.

remwines · **Posted:** Mon Feb 09, 2015 12:50 am

Today, I removed everything from the Jeep as though I were changing the timing belt and removed the harmonic balancer (crankshaft pulley). It was sure enough shot! The rubber was dried out and cracked in several places. I put the balancer in a vise, and with a punch and small ballpeen hammer, I knocked the weight out of the pulley with just a few blows. The rubber was rock hard.

I do not recall inspecting the balancer when I did the timing belt about 35,000 miles/3 years ago. So I suspect the balancer had signs of failure back then and I didn't catch it. Hard lesson learned! Unfortunately for anyone wanting to inspect their balancer, it has to be removed from the crankshaft to see the rubber.

Since I removed the fan assembly, I will replace the fan clutch. At 135,000 miles and the amount of work it takes to get at it, $110. for an OEM fan clutch seems reasonable.

geordi · **Posted:** Mon Feb 09, 2015 1:15 am

NO! Don't waste your money on the factory fan clutch, it is complete crap. The Hayden Heavy Duty clutch is the better option. The factory clutch fails nearly immediately.

As a side benefit, the Hayden is available from your local auto store for about $40.

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geordi · **Posted:** Mon Feb 09, 2015 1:20 am

Oh, and meanwhile, while you have the shroud out... Save yourself the hassle of reassembly, and do the "fan shroud mod" by cutting the sides just below the top mounting tabs. There is a thin mold line in the plastic to guide you. The bottom can be tossed, it sits too far away from the fan blades to do anything for the airflow anyway. The top then becomes a "safety cover" to keep your fingers out of the fan blades.

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remwines · **Posted:** Mon Feb 09, 2015 3:23 pm

Thanks geordi. I cancelled the OEM fan clutch order and have a Hayden 2905 on the way. I will cut the fan shroud to make working the front of the engine easier in the future. The crankshaft pulley had to be shipped from Detroit to the dealer, so it will be awhile before the Jeep is back together.

Thanks for the help.

JoeStretch · **Posted:** Thu Feb 19, 2015 5:13 pm

Hey Remwines, did you get your new balancer yet? I was waiting for the next pay period to order mine, is the part # that you mentioned just the pulley and rubber and I just reuse my weight?

remwines · **Posted:** Thu Feb 19, 2015 10:38 pm

I received the new pulley/balancer but have not re-assembled everything yet. I am waiting for delivery of a new thermostat assembly from Jeff Bauer at 4J/1G Engineering in Alberta. I want to change out that lousy oem thermostat while everything from the front of the engine forward is off, making it a bit easier to get at the thermostat.

The pulley/balancer that I ordered is a complete assembly. Pull the four bolts that holds it to the crankshaft and it comes right off. Once off, you can see the condition of the rubber between the weight and the rest of the pulley assembly.

remwines · **Posted:** Thu Apr 09, 2015 12:50 am

I just wanted to do an update since reassembling the Jeep. In all, I replaced the engine mounts with OEM parts, fan clutch with Hayden 2905 Heavy Duty upgrade and installed the new vibration dampener (Crankshaft Pulley). The new engine mounts greatly reduced engine vibration and noise being transmitted into cabin. The Hayden fan clutch pulls a lot more air at idle than the original when I bought the Jeep with 36,000 miles on the clock. The new crankshaft pulley eliminated the rattle. I also installed the Hot Diesel Solutions Model 001 Thermostat with the 203 degree thermostat. The engine runs great at the warmer temperature. Happy to have it back on the road! Thanks for the help with getting this done.

geordi · **Posted:** Thu Apr 09, 2015 12:56 am

Glad to hear it is back on the road, enjoy it!

Rattling noise at idle

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