Just another "what's that strange sound" question

[jugghead23]

Ok, I have a 98 TJ SE 5-speed. 2" Skyjacker coil spacer life and shocks (note: the sound I'm about to describe started BEFORE the lift was installed). The jeep only has about 48k miles on it so it's relatively low mileage.

Anyway, about mid-winter, all of a sudden I started getting a 'clunk-clunk-clunk' in low RPMs (around 1600-1800) in 1st and then again in 2nd gear. Once I've accelerated past those RPMs, everything works itself out and runs smoothly with no noises. The sound also occurs if I go over a marginal bump while the transmission is in neutral. If I go over the same bump while in gear, the sound is less likely to occur.
The sound seems to be coming from around the front of the shifter below the dash/firewall. The jeep does not shimmy and for the most part drives fine and shifts smoothly.

I am hardly mechanical so please excuse me if I sound ignorant.
Shortly after the noise started I installed the lift with a friend. All shock mounts are tight, all sway bar ends are tight, we also installed a new steering stabalizer and kinda 'wiggled' all of the steering components.
We also checked the exhaust and nothing SEEMED loose. same goes with the front driveshaft and u-joints. Again, nothing SEEMED loose but let me again reiterate, I am not a mechanic.

Anyway, last week, I had the jeep to the local STS (people I've known for years and trust before you all start groaning) for an alignment. I asked them, while you're under there, can you see if you can locate something loose. They came back and said the exhaust looks good and so do the u-joints.

Okay, my long story stort has be come a long story long. I've explained as best as I could. Most people tell me 'turn your radio up' but I'm determined to find the culprit. To me it sounds like something is simply loose and under low RPM vibrations is just shaking. Could this be the transmission mount? Motor mount? I've ruled out anything suspension or steering related. The only thing I can think is exhaust or transmission related (since the noise occurs freely while in neutral over bumps)

Next part of my question, does anyone know a good reliable mechanic in the Rahway/Clark/Woodbridge area of NJ? I have a feeling I'm going to need an expert opinion (or two). What about you jeepers, any experienced guys in my area want to swing by and give me their opinion?

Thanks in advance for any help.

 

[Tug-n-pull]

Check motor and transmission mounts. tug

 

[jugghead23]

that's what I was thinking, but don't know how to go about that. I'm still learning as I go.
Seems that 48,000 miles might be a little early for motor and/or transmission mounts no? The jeep did sit for a few years while the previous owner was off at school.

 

[jugghead23]

bump....just wanted to keep this post close to the top..
I know I wrote a book so I apologize...was trying to give as many details as possible.

Again, any trustworthy mechanics in the central jersey area?

 

[graewulf]

hey, if you feel like a drive down south (ocean county) me & a friend are pretty good with jeeps and vehicles in general, we'd love to meet a fellow member & help you diagnose it if you'd like... no guarantees we'll find it but you never know. is it a tire rotation clunk or a driveshaft clunk (faster)? also, does 2wd/4wd change it any?

 

[jugghead23]

I am actually born/raised in Toms River.
You make a good point, today it is wet out so I'll throw it in 4h and see if that changes it at all. I am not sure if it is driveshaft or not..I just assumed it was. I'll be in Pt. Pleasant this Saturday. Where in ocean county are you?

 

[flyboy]

Jeep clutch master to GM slave

I think I know what is. My 99 does the same thing. It will get a little worse over time but it is nothing to worry about. Can you feel it through the floor with your right foot right near the gas pedal? If you can it is simply the mount for the 4wd shifter. You can also check it by holding the shifter down over some of those special bumps. There is supposed to be a grommet or something there to keep it from rattling but mine was long gone before I figured out where it was coming from.

 

[graewulf]

more gross jeep abuse

I am actually born/raised in Toms River.
You make a good point, today it is wet out so I'll throw it in 4h and see if that changes it at all. I am not sure if it is driveshaft or not..I just assumed it was. I'll be in Pt. Pleasant this Saturday. Where in ocean county are you?

Manahawkin.... have a garage we can get you into (dads place). I think it may be a driveshaft, we can jack it up off all 4 and check it out... sometimes its easier to diagnose that way. also, we may be testing out the lift on the XJ sat (if it shows soon) if you really wanna find the rattle... :wink: My driveshaft started to clunk-clunk 2 weeks ago when offroad, now it squeaks at low speed (under 25MPH, most likely the center bearing in the CV joint)

 

[jugghead23]

put it in 4h leaving work yesterday and the clunk-clunk still exists at low rpms and over bumps.
Can't make it as far as Manahawkin on Saturday, have a busy day. I appreciate the offer though

 

[flyboy]

it will still clunk in 4wd it is just the mount pivot part. Climb under your jeep and wiggle the 4wd shifter from under neath and you'll hear the same noise you're hearing inside.

 

[jugghead23]

Neuroc @ Paragon

just wanted to follow-up on my orginal post from way back.

Anyway, never having been able to discover where the clattering was coming from, I finally decided to bring the jeep to the dealership (Frystock in central jersey).

Explained to the service tech what I had done to try and track it down, also was sure to explain that the sound started PRIOR to the lift so they couldn't try and pin it on that.

Anyway, dropped it off, they called me at work about 2 hours later and said "all done".

According to them, it was "excessive slack in the transfer case linkage" and also "while we were in there resecured wiring harness to the firewall which had fallen loose" Total for the work... $72.

To be honest, the jeep is purring right along and I'm very happy. That damn rattle started in January and I did everything I could to track it down. So the money is no big deal, I'm just happy to have my 'heap' sounding less like a bucket of bolts again....at least until the next thing!

Figured I'd post the follow up just in case someone else had a similar rattle and has yet to track it down.

 

[jeep90]

it is really tough to explain sound through words, but i will try anyhow because i think that i am having the same problem. when you would down shift coming up to a stop sign or whatever at low rpms would it sound like almost a gurfling sound? thud, thud, thud and if you didnt know any better you would swear that it was the exhaust? its just so weird that i finally got so sick of the noise after today that i was going to dive into this tomorrow. i would have never guessed that it was the t case linkage