Chain Noise While Driving

[boganst]

2001 TJ 2.5

Once I get up to 20 mph or so I can hear a metallic, loose chain sort of noise. I thought it might be a rattle but I can't find anything loose. Also, it does not change tempo with speed, gas, clutch, shifting, or anything. Once it starts up it just kinda rattles along until I come close to a stop. I can't recreate it on the driveway. I am starting to wonder if it is the front drive shaft or something in the transfer case that is spinning idle while in 2WD.

4WD seems to work fine, but I have not gotten up to the speed the noise starts (20mph) as I don't have any dirt or gravel.

Figure I will take the front drive shaft off and see if that is it but figured I would ask around at the same time. Thanks for reading.

 

[gasiorv]

Not saying this is it but Transfer case is a chain drive and the chain will be slack and spinning when front wheels spin in 2wd. Google how to check TJ transfer case chain slack and there is a bunch of info and videos on how to do it.

 

[CharlesHS]

You should not be hearing chain slop from the t case.
IF you can; then I would be worried about the chain coming in contact with the case halves…
A friend of mine and I had to deal with that situation in Moab in the campground behind our cabin.
Split the case, replaced the chain and clean thoroughly cleaned the inside before reassembling.

 

[boganst]

I'll check the slack tonight. Thanks for that tip. I just did a drain and fill and did not find any shavings or metal.

Would old u-joints cause a chain dragging like sound?

 

[CharlesHS]

Old U joints usually make a squeaking sound when the needle bearings are dry.
You can see shiny spots on the U joint coups.

 

[boganst]

Been a while. I found the video on how to test slack and didn't come away finding any issues. So I removed the front drive shaft and have been driving like that for a while. I thought I found the problem, however, I can still hear the chain dragging noise especially when I shift to 3rd or 4th a little early and the jeep is trying to get up to speed for the gear or when at 50 mph in 4th I let off the gas and just coast. Also, when I push the clutch in the chain dragging noise goes away. Appreciate the advice/insight.