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Go Back JeepForum.com > Models > Jeep Grand Cherokee & Commander Forums > ZJ Grand Cherokee Forum > Slight Whine at Idle. Source: Transfer Case?

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Unread 09-18-2014, 06:29 PM   #1
MrRoundel
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Slight Whine at Idle. Source: Transfer Case?

My Jeep has developed a transmission fluid leak. Not huge, but probably too messy to ignore. I changed fluid, filter, gasket, and solenoids last year, about 10K miles ago. While I was underneath, trying to find the leak, I heard a slight whine while the car was idling. I thought it was the transmission, but with my super-keen hearing, I traced it to the transfer case. There is evidence of what might be a slight seep at the back of the NP242, but it just a little grime stained, not wet. I checked the fluid level, and it's a bit high if anything, as it seeped out of the fill hole when I removed the plug slightly. I haven't noticed it while driving at all, but am almost never in 4WD mode, FWIW.
Isn't there a vacuum actuator inside the case? Could that be making noise? Or? Any thoughts, warnings, etc., are appreciated.
Oh, and I just put new tires on the car, so I'm sure that it could have something to do with it.

'98 Laredo, 4.0L, Selectrac NP242 TC. 180K miles now.

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Unread 09-18-2014, 06:40 PM   #2
mrgimble
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If the Jeep is not moving there is nothing that is moving inside the transfer case to make a noise. There is no vacuum actuator in the TC.
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Unread 09-18-2014, 07:03 PM   #3
MrRoundel
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Thanks, mrgimble. Maybe it's being transmitted from the transmission? I placed the stethoscope on the TC and heard it, however, could not hear it at the tranny pan. I ran the TC through the selections while at idle, and nothing made any strange sounds while doing so. It seems as if the noise only happens while in Park, not even in neutral. Any ideas? I got a check engine light that pointed to a minor leak in the evaporative emissions system. Since it was minor, I've been letting it go. I just thought about it, and by not correcting it, the OBD might be trying to tell me something, and I'm ignoring it, thinking I know already. Hmm...I'd better get that OBD back on there, and see if there's something else showing.

My Jeep has been driven 179,000 of its 180,000 in 2WD, of which 125,000 have been highway/mellow canyon driving, FWIW. I consider it pretty well babied, arguably too much so.

Added: Well, my minor evaporative leak has morphed into a major now. I believe that I had read that this is a normal progression. PO442 and PO455 now showing.
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Unread 09-18-2014, 09:03 PM   #4
KJK
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The whine you are hearing is probably the regulator valve in the transmission. It's a common issue that really doesn't harm anything. There's an aftermarket one available made from steel instead of aluminum which tends to minimize the whine. Google it for more info.
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Unread 09-19-2014, 12:04 AM   #5
Uniblurb
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Check underneath to make sure the shifter cable isn't up against the engine or trans bell housing while routed correctly. You could also have some type of converter whine and is your trans fluid good, clean & full?

On the emissions systems leak make sure your hose/line coming from the fuel tank vent going up to the charcoal canister is good/not broke. Also check the canister behind the front bumper isn't cracked while the hoses going up to the duty cycle purge solenoid on the driver's fender in the engine compartment are good. Check to make sure the vacuum line going to the intake from this system is also good. The fumes from the fuel tank are eventually burnt through the engine by being drawn into the intake. You'll never pass CA inspections unless you get it fixed. Good luck!
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Unread 09-19-2014, 06:52 AM   #6
MrRoundel
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Thanks, Uniblurb and KGK.

I'll check the shifter cable, but it doesn't sound like a buzz or vibration, which it seems that would sound like.

I changed the fluid a little over a year, and 10K miles, ago, so it should be fine. I added about 1/2 pint to it the other day, but that was the first time since changing it. So there's a newer filter, and two newer solenoids that are common issues. The fact that it only seems to get the whine in Park, gets me thinking about the torque-converter, which is something I don't want to ponder. However, if it was the torque converter, I'd think I'd be hearing it at the bell-housing. The stethoscope only seem to pick it up when against the tranfer case.

It is possible that the fluid leak is related to the whine. I just noticed the leak a few days ago, and the whine yesterday. You don't really hear it unless you're outside the car when it's idling, and you have pretty good hearing, which I do. The work I'd been doing on the car, ball-joints, was being done without running the motor for testing, so I wouldn't have caught it then. So I just don't know how long it's been happening. Could be two months, could be 3 days.

Thanks again, amigos.
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Unread 09-19-2014, 09:04 AM   #7
JohnnyZJ
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its 15 years old. don't overthink it.

if you can barely hear it then it means nobody else will.

hell our 2013 vehicles make random noises sometimes at idle. i'd not worry about it. and as stated, sound is likey tranny, NOT tcase. so stop pondering haha.

as for your leaky transmission if it has been leaking since you installed new filter make sure torqued the tranny pan back on correctly.

lastly, stop worry and drive it til it explodes.
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Unread 09-19-2014, 11:46 AM   #8
NTH
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Quote:
Originally Posted by JohnnyZJ View Post
its 15 years old. don't overthink it.
stop worry and drive it til it explodes.
^ This
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Unread 09-19-2014, 12:17 PM   #9
MrRoundel
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In a world of few real coincidences, I just find it odd that the leak would develop at around the same time as my noticing the sound. My concern is due to preparation for a trip to Baja. The place I go to is a two hour dirt road ride from a town that's a few hours from civilization. If something goes wrong down there, it's never easy. I'm trying to minimize the chances of problems, that's all.

I agree that I can't expect perfection from a 16 or 17 year-old vehicle, with 180,000 miles on it. The sound, in and of itself, would not be a huge concern. It's the accompanying fluid leak that is pretty recent. While I was under the car to fix a vacuum leak (rubber house coupling where evaporative line transitions from firewall) , I saw a drip forming at the base of the bell-housing. It was not coming from the pan. It looks like it's coming from the gap between the sheet metal cover at the bottom of the bell-housing. I don't believe that this is a good thing.

It's not a huge leak, and I could probably just bring a quart of ATF with me to Baja. However, if these things tend to get worse in a hurry, I'd best address the issue before heading out of the country.

Oh, and on the vacuum leak: I figured that I was a genius because I had used a Dorman/Help 90 degree transmission vacuum fitting for the 90 for the evaporative emissions that attaches to the intake manifold. I guess the rubber they use is not able to withstand either the heat or the gas vapors, as it was all cracked and compromised after only being in the car for 6 months. I just put a piece of 5/16 ID vacuum line on it. It didn't kink, so it should be at least as good as the 90 I bought.

Thanks for your comments, all.
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Unread 09-19-2014, 06:24 PM   #10
NTH
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Sounds to me like you're describing a rear main seal weep. Seems to be very common on these as they age and the rubber seal hardens. Try googling or youtube ZJ Rear Main Seal. What color is the dripping?
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Unread 09-19-2014, 09:06 PM   #11
MrRoundel
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Quote:
Originally Posted by NTH View Post
What color is the dripping?
Red, and definitely transmission fluid.

I'm taking it in to a transmission shop tomorrow morning. I don't have it in this aging body, especially back, to be dealing with dropping the tranny myself, especially in a 4X4, with the added weight of the transfer case. I know that it's a fresh leak, so I'm hoping that I'm addressing it before it does too much damage. That said, it does have a lot of miles on it, babied or not. I do most of the work on my cars still, but I draw the line on the heaviest, most awkward, messy stuff. This surely qualifies.

BTW: I trust the transmission shop that I'm taking it to, and I like their policy. The owner will put it on the rack and give me an idea of what I'm looking at, cost-wise, etc., and has been fair and seemingly honest over the years. As long as it's not new tranny time, I'll probably make the appointment for him to do the work this week. The tranny has not been exhibiting any other symptoms aside from the leak, and the slight whine that I can hear at idle. I wonder if I'm hearing something tied to the failing seal? If it's the torque converter, than I'll have to deal with the cost. Again, I just can't do that heavy stuff anymore. I like to save what's left of my back for the fun stuff.

Thanks.

Last edited by MrRoundel; 09-19-2014 at 09:12 PM.. Reason: Add info on shop policy.
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Unread 09-19-2014, 09:24 PM   #12
Uniblurb
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It's most likely your front trans seal leaking and I'm sure they'll probably want to drop the trans while resealing it. Have them do the rear seal too as long as they have it out. As you probably found out when you changed your fluid/filter 10K miles ago every trans has fine metal in the bottom so don't let them try to talk you into a rebuild. Wouldn't doubt they may check the front pump and say it's a converter whine you're hearing.

On that 5/16" ID fitting on your intake you should really be using fuel injector hose. Old style vacuum line used to be fairly fuel resistant while the new stuff isn't. Good luck at the shop!
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Unread 09-19-2014, 10:08 PM   #13
MrRoundel
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Thanks, Uniblurb. As I said, this guy's shop has been pretty good over the years. He seems to appreciate those who have a little knowledge about what's going on, rather than resenting it, which many shops do. He probably understands that at least if he does work to the transmission, and a week later my air-conditioner fails, I won't come back blaming him, saying "It worked just fine until you fixed the transmission."

Heck, if I was that ignorant I'd be blaming the guy who did my alignment last week for the transmission fluid leak. Come to think of it...

Thanks for the suggestion on having them do the rear main as well. I'm sure that I could do that one, but if it's a reasonable add-on, I'll go for it.

Cheers.
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Unread 09-19-2014, 10:36 PM   #14
Uniblurb
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No problem and actually I was talking about them replacing the rear transmission seal if they had it out. You're right it would be easier to replace the rear main seal while they have the trans out but may not be all that cheap. They'd still have to remove the engine oil pan, flex plate on the back of crank, and rear main bearing cap. But with the trans out of the way they probably wouldn't have to drop the axle down a bunch to get the pan out since they could pull it out the back.

Maybe it's the darn alignment making that whining noise!
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-Stalling ZJ? 12 things to check before replacing a sensor; the Dirty Dozen
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Unread 09-20-2014, 07:40 AM   #15
MrRoundel
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Doh! My bad. Let the transmission shop do transmission work. I wasn't thinking when I mentioned the rear main, at least as far as the layout of things. I do know that I could do the rear main myself, as I watched a video of it, and it's not the heavy work that I avoid. Perhaps a bit messy, but that's most of it. Thankfully, the advent of nitrile work gloves had made automotive repair work much more palatable.

Believe it or not (based on my rear-main confusion), I once did a total rebuild on a 318 all by my lonesome. It took some time, some books, a fair amount of effort, etc., but it ran great when I was done. That was in one of the old '68 Barracudas I use to have. They both had 904 Torqueflites in them, which I believe is the predecessor to the 42re that's in my Jeep. The 340, 383, and 426 Hemi cars used the 727 Torqueflite, which I believe is the predecessor to the AW4. I could be wrong about that, but it seems that it fits the same, heavier torque-handling capabilities, that the 727 did. Note: I never had to do any work on the transmissions in my Barracudas.

When I compare it to my Barracudas, I think that the way my Jeep still drives is quite amazing, By the time cars got 180,000 miles on them, they were rattle-traps. Everything is still pretty tight on my Jeep. For the most part, these ZJ's are very well-made cars. I realize that more work will be forthcoming, and I'll have to make painful decisions over the next few years, but I'll keep her on/off the road as long as I can.
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