chrysler 545rfe need advice

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Hi everyone,have a little Jeep jk diesel shorty running the 545rfe trans.It started making a loud high pitch whine noise when cruising at 100kph and i would lift my foot to coast and noise starts up,only does it after about 25mins and at 75 degrees C operating temp.runs fine through all gears and after chasing diff issues/driveshafts ect we pulled the box out and had it fully stripped down but they found nothing and reassembled it with new seals,gaskets,frictions and a few other bits and pieces.The noise went away once reinstalled and now 3500klm later it has come back again. are there any transmission guys that could offer advice as the local shops don't seem to confident.i have a recording of the noise i can send if that helps.Thanks in advance.......
 
I am not a drive train expert & know next to nothing about Jeeps .

Having said that , I would investigate the diff and maybe the drive shaft .

Does it have limited slip diff ? When was the last drain & fill on the diff . Transfer case ? Front diff ?
 
It sounds like your diff fluid thins out after 25 minutes of driving and reaching 75*C. What viscosity are you using? Another possibility is is the shims for the ring and pinion are not set properly. Our 2005 Ford Explorer does just the opposite, it whines when you accelerate. It was rebuilt 3 times under warranty and it still does it. It was rebuilt by the dealer and I can only assume they don't really know how to shim the ring and pinion correctly. It has a 195,000 miles it and the whine has become a "white" noise in the background.

Whimsey
 
Originally Posted By: Johnnos
i have a recording of the noise i can send if that helps.Thanks in advance.......

Yes, care to upload the audio?
Btw, what's the oil grade in use vs what owner manual says and its L capacity?
75*C operating temperature after a 25 minute drive is too high ..... and abnormal for an unloaded machine, IMHO.
 
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Are you using a licensed ATF+4 transmission fluid?

https://www.centerforqa.com/chrysler-brands/

What I'm reading is 75°C is the ATF temperature, is that correct? My Ram EVIC displays ATF temperature but not differential temperature.

That temperature (75°C = 167°F) is about the top ATF temperature Ive seen my similar transmission reach in Texas heat pulling a trailer at 75 MPH (120 KPH). My truck has an air cooled transmission fluid cooler with no thermostat regulation.
 
Front dana 44 is aftermarket and we pulled that apart and found nothing,same for rear diff and both shafts.Having the trans out and freshened up was the only time we got rid of the noise but only for 3500 klm. Its a right pain in the [censored] trying to diagnose the issue...
 
It runs a big cooler and that temp is taken on the exit line going to the cooler after its been through the transmission.What is your normal temp on trans around town?
 
Originally Posted By: Johnnos
It runs a big cooler and that temp is taken on the exit line going to the cooler after its been through the transmission.What is your normal temp on trans around town?


Typically 140°F to 150°F in warm Texas weather, it can get to 160°F in stop & go rush hour traffic when ambient temperatures are in excess of 100°F and pavement temperature well exceeds that. However, I think my EVIC displays the transmission sump temperature in my 68RE, I think the measurement point is part of the submerged TCM in mine.

What transmission fluid are you using? Everything I've read is these transmissions are very picky about operating correctly on licensed ATF+4, or one boutiqe substitute Redline C+ that's reported to have the same additive package as licensed ATF+4 but a superior base stock. Interesting how it went away temporarily with fresh fluid of whatever you're using. It makes me curious about fluid without the correct frictional properties perhaps being at least part of the picture.

BTW I've never heard a similar noise to what you posted from my transmission.

You may find this web site to be of interest.

https://www.allpar.com/mopar/transmissions/545RFE.html
 
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Hi its only when warmed up and trying to coast at 65 mph or more,if u slow it down to 50mph after it starts it does not come back..
 
How old or maybe burnt was the ATF+4 when it started making the noise?

Any reason you used the Penrite fluid after reassembly?

Anything to lose displacing the Penrite fluid with licensed ATF+4 and seeing what results you get except whatever a system fill of ATF+4 costs in your area?
 
Trans rebuilder was happy to run this in it and we were not sure if it had fixed original problem,atf plus 4 is pretty hard to get here and super expensive.But i hear what your saying and id like that in there myself.
 
Originally Posted By: Johnnos
Hi its only when warmed up and trying to coast at 65 mph or more,if u slow it down to 50mph after it starts it does not come back..


Well that's interesting behavior, seems it's not really rated to ATF temperature if it doesn't return after slowing then speeding back up and maintaining speed, as surely this doesn't significantly change the ATF temperature, right?

It does sound like it's only an effect in (initially?) engaging overdrive gear, for whatever reason, but you've had it torn down and reassebled. Maybe an intermittent electrical fault with the overdrive solenoid?

I'm really just blue-skying at this point. Those are my only two thoughts on the issue - overdrive circuit or fluid compatibility / suitability. A shame licensed ATF+4 is expensive there - here it can be purchased for US$4.27 per quart at Walmart.
 
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Im thinking about putting in a modified sonax valve body with new oem mopar solenoid block and finding some atf plus 4,I'm sure i have seen it here and its the small bottles only and its like $24 per litre or something.It does return if i go over 50mph ,its coming out of overdrive i think thats the problem.foot back on the gas and it go's away while accelerating,throw it into neutral while its playing up and instantly stops making the noise.
 
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Originally Posted By: Nyogtha
Are you using a licensed ATF+4 transmission fluid?

https://www.centerforqa.com/chrysler-brands/

What I'm reading is 75°C is the ATF temperature, is that correct? My Ram EVIC displays ATF temperature but not differential temperature.

That temperature (75°C = 167°F) is about the top ATF temperature Ive seen my similar transmission reach in Texas heat pulling a trailer at 75 MPH (120 KPH). My truck has an air cooled transmission fluid cooler with no thermostat regulation.

Oops, it isn't about differential oil temperature, my bad.
Anyway, ATF unloaded touching 75*C in 25 minutes may be 'normal' in some transmissions, but a thicker shear-stable gear oil in synchromesh gear oil having higher KV40/KV100 would be desirable in this context, IMHO.
 
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Originally Posted By: Johnnos
Im thinking about putting in a modified sonax valve body with new oem mopar solenoid block and finding some atf plus 4,I'm sure i have seen it here and its the small bottles only and its like $24 per litre or something.It does return if i go over 50mph ,its coming out of overdrive i think thats the problem.foot back on the gas and it go's away while accelerating,throw it into neutral while its playing up and instantly stops making the noise.


OK that helps understanding. If it was an issue with lockup you'd expect shudder, which I have temporarily experienced after a drain & fill with fresh ATF+4 as the TCM adjusts from somewhat worn fluid to fresh fluid being put in the system. My intermittent shudder at lockup went away after 300 miles after my frain & fill which replaced 50% or so of the system inventory (7.5 qts fresh licensed ATF+4 fluid).

Well, there's a thought, but not a really happy one. Might be something wonky in the TCM, it should have reset to "relearn" after being disconnected from the battery while you had it off for assembly & disassembly. Just for kicks, at zero cost, you could try disconnecting the battery for a short period to reset the TCM again and see if it goes away again, even temporarily.

Keep in mind any brand of licensed ATF+4 from the list in the link I previously posted is acceptable. It does not have to be OEM Mopar ATF+4. The Penrite fluid you're currently using is not on that licensed ATF+4 list and no broad spectrum multi-vehicle ATF is on the licensed ATF+4 list. You could print out that list and take it to your mechanic and most convenient auto parts stores to have them see which of those licensed brands they may be able to acquire along with pricing. Plus, there's eBay and Amazon to check. I'm currently running a 50/50 mix of factory fill ATF+4 manufacturedby Shell (Pennzoil) here and Havoline (Caltex to you I think, now owned by Chevron) ATF+4. Chevron makes a licensed ATF+4. Castrol makes a licensed ATF+4. Even Sinopec and Quanhu (DFM Castrol) make a licensed ATF+4 which may be more readily available in your hemisphere.
 
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