danielr-lv

Hello.

Please bear with me, as I am not a mechanic. If I left out any key information, let me know and I will make it available. I have a 2002 Grand Cherokee Laredo 4x4 v6 with an automatic transmission. I have ~220k miles on it.

Up until last night my Jeep has been running flawlessly. I change the fluids and do routine maintenance myself as scheduled. I was going to make a quick trip to the store and once I got going to about 40mph and a really terrible grinding noise made its self apparent. It seems to be located underneath the center console.

I immediately turned around and went home fearing an imminent transmission disaster. I checked my transmission fluid and it is still bright red, doesn't smell burnt, and reads at an appropriate level on the dipstick.

It was pretty late, so I went to bed and set my alarm early to do some more troubleshooting.

These are the things I have checked as of this writing:
- Transmission fluid. Seems to be acceptable. Seems to be shifting fine as well. No hesitation, and shifts gears smoothly.
- 4x4 works, noise is still there
- U joints. No play at all in rear drive line. Feels solid. The line coming out of the transfer case feels solid, but may have a very slight amount of play
- I didn't notice anything physically out of place or rubbing where it shouldn't be, but again I'm not a mechanic.
- The transfer case is slightly wet around the seal towards the bottom, but there are no fluid deposits on my driveway.

This noise isn't present at all if I am stopped, and is not consistent when driving. Once it starts, its very loud and sounds like grinding rocks. It does stop after a few seconds as well, or just pops once or twice. I can feel it through my shift lever. If I tap on the gas pedal, it seems to stop the grinding sound momentarily.

Any input on this issue would be greatly appreciated. I just want to make sure its not a silly problem before I take it to a mechanic. Thanks in advance.

rawk krawler

Check case fluid

danielr-lv

I will as soon as I get home tonight.

dave1123

It's possibly a broken drive chain in the transfer case. If this is the case, the front axle will not be driving and the chain will be slapping around inside the case.

danielr-lv

Update:

I tried to start it, and the starter is completely hosed. Perhaps this is the issue?

dave1123

Okay! with that in mind, the spring on the starter drive is probably broken allowing the gear to slide back against the flywheel. If this is the case, you may wind up replacing the flexplate (flywheel). You can pull the bottom cover and inspect the gear on the flexplate and make a decision. I had a Chevy that the PO had replaced the starter with one for an automatic trans when it was a standard trans. The difference in engagement length was only 3/8 of an inch, but it wiped out the leading edges of the flywheel gear. The gear was worse in some places than others and if it stopped in those places, the starter would grind.

Replacing the flexplate requires separating the engine and trans. It's a simple job mechanically, but a PIA labor wise. You'll need many blocks, jacks, possibly a chain fall or engine hoist, and a torque wrench. Also a blue vocabulary is helpful, LOL!

danielr-lv

Had the starter + battery tested. No dice, both checked out fine.

I bypassed the starter and it spun up, but didn't engage, just spun. I looked at the fuses and they all seemed fine.

danielr-lv

Bypassed the starter again and it fired up. Im going to limp home where I have tools.

danielr-lv

Does anyone know a ballpark cost for a transfer case swap at a mechanics shop? I just called two places and they wouldn't give me a straight answer.

Is this something that someone with basic mechanical skills could do themselves?

dave1123

Yes, but it is quite heavy and awkward to handle. It would be better with some experienced help. Especially to make sure you have the right one. Is it the Selectrac (with the 2WD option) or AWD?

This is major surgery, so make sure it's the problem before you tear into it.

danielr-lv

I limped it home, but it drove like a champ with no grinding at all. The engine drove smooth, the gears shifted, no grinding noise whatsoever. The transfer case IS leaking and IS a little bit low on fluid. I am going to change its fluid tonight and see if its burned up or any shavings fall out, but that doesn't solve the problem with the starter.

I bought it used about a year ago and they claimed to have flushed all fluids. This is the first problem that I've had with it other than a dead battery. I'm surprised its lasted so long and runs as good as it does having 220k miles on it.

If anything, I will keep this thread up and going until its fixed in case its useful to anyone in the future having similar problems.

btw dave1123, its a 242j case.

dave1123

If it drove home with no noise, I'm willing to bet the problem is with the starter. If the drive is not retracting all the way, it could be hitting the flexplate gear. I've seen this happen with a leaky rear main seal gumming up the starter drive shaft and not allowing full retraction of the drive gear.

I had a friend with a Chevy. When he started it, the engine gave out a terrible racket. Instead of shutting it off to investigate, he revved it up. He blew the starter right off the motor, breaking the bolts and tearing up the metal shield and bending the flexplate.

danielr-lv

This morning, my Jeep fired right up with the key, but has started throwing a p1899 - Neutral Safety Switch code. Drove around the block a few times, no grinding noise.

Tonight, I am going to replace the starter anyways because I'm sure its likely going to fail soon anyways (pretty sure its the original, 12 year old starter) and double check all the wiring to it.

I checked the transfer case fluid, and it looked to be full. I am going to change its fluid this evening because I have no idea when it was last changed. The guy I bought it from claimed that everything was changed before he sold it to me. The fluid was still red, didnt smell burnt, but was a little bit dirty.

I'm also going to see how much of a PITA cleaning the NSS is, and clean it if its still in good shape.

Does all of this sound logical? If I am missing anything obvious or anyone has any suggestions/things to check, I'd really appreciate the input. I'm not a mechanic, but I am definitely not scared to get my hands dirty and at least attempt to fix things.

dave1123

According to my Haynes manual, if you have the 42re or 46re trans, it's screwed into the case of the trans. If you have the 45rfe, it's inside the trans on top of the valve body.

IMHO, replace it.

Something is stirring the cobwebs in my brain. Could it be possible that something is energizing the starter while you're driving? Like maybe a bad ignition switch? Just thought I'd throw that out there and see if it comes back. Also, check to see if it will start in gear. That will tell you if the NSS is stuck in Park.

danielr-lv

I found this link http://xjtalk.com/showthread.php?p=157701 that shows a nice set of pictures/walkthrough for cleaning a NSS. It doesn't look too bad. I figured I'd drop $10 and an hour or two of my time before spending $300 on a new one. Worst case scenario, I break it and have to buy a new one anyways.

The thought of the ignition switch being bad and causing it to engage while driving has crossed my mind. Does anyone know of a way to test these short of just replacing it?