46RE Transmission Hydraulic Noise?!?!?

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#1
Okay guys, back for more help. Thought I fixed my last problem, new problem popped up. Background: 1998 Jeep Grand Cherokee 5. 9 Limited (46RE tranny). Recently rebuilt, custom valve body from APS, lots of goodies, etc, etc. I was dealing with an issue where it wouldn't shift out of first gear. Had some springs mixed up in the VB. All is well in the world.

The other day I was enjoying my Jeep again running errands, and I noticed a very weird sound. Whenever the tranny is in any range OTHER THAN park, it makes a hydraulic noise. Best I can describe it is the moaning sound an old ford steering pump used to make when it was getting old and you turned the wheel. In fact, at first, I actually thought my power steering pump was going out. Popping the hood proved I was wrong. This sound is RPM dependent, doesn't seem to sound any louder or quiter in any particular range than another. As mentioned, it doesn't make this noise in park, but it does make it in neutral. It sounds like it is coming from the bellhousing area.

Another interesting twist. The sound is RPM-dependent, meaning it gets louder with engine RPM. However, about a half-second before the tranny shifts, the sound goes away. It comes right back after the shift is completed, and will go away immediately preceding the next shift. And during the 2-3 shift, it feels like the tranny is momentarily letting go.

Lastly, it sounds like there is a mild mechanical sound (scraping and banging) noise in the mix, too.

Now, my research has yielded a couple possibilities, which I will list here:

1. Torque Converter - Heard this as one of the most frquently cited reasons for sound coming from the bellhousing area. However, most things I've read say that this sound disappears in Park AND Neutral. I did a stall test and RPM was normal (about 2500 - it's an APS converter, nominal 2500 stall).

2. Flex Plate - Heard these can crack or the bolts can be loose. In all my years of wrenching I've never seen it but okay. That would certainly explain the mechanical sound but I don't think it explains the hydraulic sound. Also, wouldn't it be making noise in park if this were the culprit? Easy enough to check, just pull the inspection cover.

3. Plugged Filter - I've heard this noise can be caused by insufficient fluid flow, caused by a plugged filter. I fear this one not because changing the filter is difficult or expensive, but because that means my new tranny is generating enough debris to plug a filter = no bueno.

4. Cooling System Restriction - similar to the filter problem above. Heard this can be a problem. I figured a somewhat easy test would be to take like a two-foot piece of tranny hose and "short-circuit" the cooler ports. Take the inlet and tie it to the outlet. If the sound goes away, hope a flush will clear it. If not, new radiator time.

5. Valve Body Problem - I've heard a buzzing valve inside the VB can cause this sound. The fact my sound goes away right before shifting somewhat supports this. My VB has the no-buzz PR valve and TV and all the other fancy valves known to buzz. However, I've heard crap can get into one of the valves and cause it to buzz. The VB was assembled by Wayne at APS. Again, my concern here would be how the crap got in the valve in the first place.

6. Internal Damage - God, I hope not. I just don't know what would be making noise in N but not in P. However, internal damage might pollute the tranny with debris, possibly contributing to 3) or 4) above.

Can anybody help? Any ideas? I'm sick of dumping money into this transmission!
 
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#2
I started researching my backup plan, which is to buy a Level 3 Mega Viper transmission from PATC. I'm just tired of dealing with it. ANyways, I've called these guys before and they have never refused to answer a question for me, so I'd figure I'd ask what usually causes a whine. The guy was definitive - torque convertor or pump. I asked about the fact that it still makes noise in neutral and he said you can't count on that anymore. Sometimes they do, sometimes they don't. What I do know is that a 46RE charges the converter in N, but not in P. That said, my shift kit came with a manual valve that is supposed to allow converter charge in P.

The phone call was not without humor. I asked him what the easiest was to diagnose either problem was. His response - "disassemble 'em".

Any comments?
 

billr

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#3
Good news is that a tranny expert has joined us recently who is participating daily, you will get some feed-back soon.
 

bp042665

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#4
ok Billr im here and yes the converter can be the problem but first thing first take the inspection cover off and be careful and check each converter bolt i recomend putting lock tight on them cuz they will back off been a mechanic for over 30 yrs and i have seen loose bolts alot if all bolts are tight start it and make sure you get someone you can trust to hold the brake and try to listen to it with mechanic ear or piece of tubing thats will help pin point it better let me know what you find and ill try to help you more if needed
 
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Again, I certainly must agree with you that loose TC bolts could certainly cause the mechanical I'm hearing. But could they cause the hydraulic sound? I mean, it's pretty distinct. Sounds like an old power steering pump whining. If you say it's possible then I won't question you. But I am just having a hard time drawing the line between "loose bolts" and "hydraulic noise". I await your reply.
 

bp042665

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#6
if the pump gears are worn they will whine I have a 1997 Dodge P/U and i built it about 4 yrs ago and mine has a whine 6 months after building it but I'm still driving it lol have you took out the 1 way flow valve in the cooler line i highly recommend it cuz if it starts to stick shut it can make the pump whine and also Quite lubrication to everything in the OD unit and cuz expensive repair
 
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When I did my rebuild, I removed the check valve, as well as backflushed the cooler circuit with that "Kooler Kleen" stuff.

Anyways, we have 6 inches of snow on the ground and the thought of parking my commuter car outside overnight and scraping the windows in the morning so the jeep can be in the garage doesn't appeal to me. However, I have a 4-day weekend coming up and will be able to check some things. I have ANOTHER case of ATF+4 on it's way, and will pick up a filter and pan gasket tomorrow, and might as well get another can of Kooler Kleen.

When I pull it in the garage this weekend, first thing I will do is remove the inspection cover on the tranny and confirm the torque converter bolts are tight and verify the drive plate is not cracked. I will admit that when reinstalling the transmission, I did not use a torque wrench on the torque converter bolts. However, the torque spec is only 21 ft-lbs, and I'm reasonably sure that I got them at least that tight.

Next order of business will be dropping the pan while praying I don't find anything. My hope here is that the filter is just partially clogged. My research has yielded many people whom have the same whining noise as me and it turned out to be a plugged filter. Fingers crossed. If that doesn't fix it, I'm 99% sure its the pump. Even if it's not, the tranny is gonna have to be dropped one way or another, unless its the valve body. A lot of people mention that the valve body could be the cause IN THEORY (if a valve was buzzing), but I've never actually seen anyone say it was their problem.

I've all but ruled out the TC at this point because a bad TC tends to make the most noise when you place it in D or R and hold the wheels stationary with the brakes. At this point, the turbine (hooked to the rest of the drivetrain) is held stationary, while the impeller (hooked to the engine), is moving. Giving a little gas (as in a "stall test"), should exacerbate the problem. In P & N, the turbine and impeller are spinning at the same speed. As you recall, my converter passed a stall test fine without any add'l noise so I can all but rule that out.

Lastly, another test I was told I can run is this - Disconnect the TV cable and pull it by hand, which will modulate the TV valve inside the valve body. This will vary the load on the pump. If the pump is the culprit (or the filter), the noise should modulate in pitch with it. This helps you seperate it from a mechanical sound (like a busing going out) because the rotational speed is not changing during this test.
 

bp042665

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#8
ill be checking in a few times a day so if you have any issuses ill try to help but you sound like your on the right track and i have seen a buzzy noise from the VB but you can check it with the Mechanic ears or a peice of tubing at the pan and see if its there cuz with the 1 way valve out the fluid flow is increased and will buss the valve but not to worry
 
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I appreciate you checking in. I will be posting a lot of information this weekend.

I hear what you are saying about the valve body and it being a valve, but the tranny ran for months with the check valve removed and no buzzing. This sound started only recently. As such, I'm trying to look at things that could start "all of the sudden". As I say this I am realizing that a valve starting to buzz is every bit as likely as a torque converter failing or a pump starting to whine "all of the sudden", lol.

Hopefully it will turn out to be a clogged filter, nothing more. Then of course I will be freaking out wondering what clogged my filter. It's usually not a good sign when a filter clogs "all of the sudden", correct?
 

bp042665

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#10
no it isnt but i know you flushed the cooler but i have seen trash still come out of it month later and stick a valve so let me know what you see in the pan it might help me help you
 
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bp042665 said:
no it isnt but i know you flushed the cooler but i have seen trash still come out of it month later and stick a valve so let me know what you see in the pan it might help me help you
Well the other thing that I will state here for completeness' sake is as follows.

If you follow my entire saga in another thread, when the tranny failed (due to being old), which is why I rebuilt it in the first place. I decided to rebuild it myself for experience as an avid DIY'er and to save money. First part happened, second part not so much. Top notch components, 5-pinion planets throughout, oversize servos, red eagle power packs, kevlar bands, yada yada. Also purchased an APS precision 2500 stall converter.

Well, during my first reassembly, I set the end play too tight. This drove the stator support into the direct drum and siezed one of the sealing rings onto the shaft. This caused a massive leak in the rear clutch causing a loss of movement in all forward gears, but I still had reverse. All the while debris was circulating through the transmission and plugged the filter, restricting fluid flow. At this point I lost reverset and he vehicle was immobilized.

Back out the transmission came. Diassembled it and cleaned everything to ensure all debris was cleaned out. However, as you know, getting all the fluid out of the TC is impossible. Did the best I could but I know I didn't get it all. I know you're supposed to replace a TC with any failed tranny, but I just couldn't make peace with the thought of spending $450 to replace a TC that had 5 miles on it.

So I guess what I am getting at is maybe whatever debris is was left in the TC made it back around to contribute to filter pluggage.

Am I being reasonable or is this just wishful thinking on my part???
 

billr

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#12
I think that is reasonable "wishful thinking"... too bad it doesn't have an external spin-on filter that you can easily change a few more times.
 
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#13
When I rebuilt the transmission, I definitely looked at adding an external filter. I eventually passed it off since I had a hard time locating a good spot and thought it was frivolous. However, given the current circumstances, maybe I should look a little harder.

I'm gonna change all the fluid if I determine the source to be hydraulic. Maybe I can just keep filtering the contaminants out.

One other thought. A buddy of mine suggested taking it to a lube place and having a power flush done to get all the crap out. Thoughts? I know that, in general, power flushing is frowned upon. However, the thought is that since the transmission is brand new, it wouldn't do any harm. Is this legitimate thinking? Do they do any good at cleaning the TC?
 

bp042665

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#14
well at most places the only use a globel fluid and some times it not compatable in all cars but you can buy a external inline filter and install it on the return line very easly most good parts stores can get them and the retun line is the one with out the check valve in it
 
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#15
I was looking at putting some magnefine filters in there. Anybody have any experience with them, good or bad?

http://bossproductsusa.com/products.html

I was thinking a magnefine inline filter on the return line and a magnafilter on top of a wix/napa gold on a remote mount filter setup for the supply side. I know it may be overkill, but when you spend 3 grand on a tranny, overkill is underrrated. Besides, with both filters being external, cleaning up the fluid (or keeping it clean) should be a lot better.

Thanks again all for all the help. I am gonna run some tests tonight and I tentatively plan on pulling the jeep into the garage and letting it drain overnight. My new ATF+4 doesn't come in until tomorrow anyways.

Stay posted.