Looking for circulating pump for G56

[zzman]

Well after all the research and info I gathered and the other issues I've had, I FIXED my G56 overheating problem.

Traded it in for an automatic an Aision 6 speed with the 2011 3500 cab and chassis. No more standards, at least no more G56 trans.

 

[EMAC2]

If I may ask, why the concern with heating in the G56? The synthetics have much higher temperature ratings and no degradation from those higher temps. The seals might be a weak point, but without concrete data to support the seal/bearing choice used by MB I am wondering why this is assumed to be an issue in the standard G56.

Are there definite records of G56 failures due to heat?

 

[zzman]

I can only speak from my experiance with this trans.
I can compare the results I have had with the G56 and the NV5600. The NV did not get near as hot as the G56 did pulling the same load.
The G56 had the magnet on the drain plug full of shavings after 20k miles.
The G56 would whin in 3rd, 4th and 6th gear after it was good and warmed up. Also the G56 would be harder to make a smooth shift.

I've heard that there is a "girdle" or something that can be attached to the outside of the aluminum transmission to help reduce the flex of the case. That alone is a "red flag" to me. Also I hear that the new trucks with the manual trans will have the engine turned down some compared to the auto trans. For the mfg to enforce that statement, tells me to beware of the G56.

That's all I know... .

 

[RVTRKN]

The theory is to keep it cool to prevent flexing from softening when it gets hot. Per TDR member CKelley1, he installed oil coolers instead of girdles hoping that keeping them cool would prevent the flex. And while running at 40K GCVW for over 250K miles, and never having to open one up says a lot, and not just lucky with one, but with a fleet of G56's from the first productions to the latest behind 6. 7's. He has convinced me to just install the coolers seeing how I will only pull at a max 23K GCVW, I was going to install a girdle at $1000. 00 a pop. Oh by the way, he fills them with his blend of mobil delvac trans oil.

zzman, owners of the Aisin seem to like them, it has made me wonder if I chose the right transmission for my truck. But now that the DMF will be replaced with a solid flywheel and coolers installed, and filled with Mobiltrans SHC oil, one of two oils authorized for the Mercedes Benz G56, I think I will be happy with it. I always knew that one day the DMF would fail, and the time has arrived, in 10 days the trans will be pulled and inspected and cleaned and filled with Moibiltrans SHC oil, SMF and the SBC DD 3250 clutch.

 

[RVTRKN]

The theory is to keep it cool to prevent flexing from softening when it gets hot. Per TDR member CKelley1, he installed oil coolers instead of girdles hoping that keeping them cool would prevent the flex. And while running at 40K GCVW for over 250K miles, and never having to open one up says a lot, and not just lucky with one, but with a fleet of G56's from the first productions to the latest behind 6. 7's. He has convinced me to just install the coolers seeing how I will only pull at a max 23K GCVW, I was going to install a girdle at $1000. 00 a pop. Oh by the way, he fills them with his blend of mobil delvac trans oil.



zzman, owners of the Aisin seem to like them, it has made me wonder if I chose the right transmission for my truck. But now that the DMF will be replaced with a solid flywheel and coolers installed, and filled with Mobiltrans SHC oil, one of two oils authorized for the Mercedes Benz G56, I think I will be happy with it. I always knew that one day the DMF would fail, and the time has arrived, in 10 days the trans will be pulled and inspected and cleaned and filled with Moibiltrans SHC oil, SMF and the SBC DD 3250 clutch.

 

[RVTRKN]

Also I hear that the new trucks with the manual trans will have the engine turned down some compared to the auto trans. For the mfg to enforce that statement, tells me to beware of the G56.

That's all I know... .

The 6. 7 W/manual have been detuned ever since the 6. 7 production came out with the higher HP and TQ over the 325/610 in the early trucks with the 5. 9.

 

[RVTRKN]

zzman, I found this old thread of yours, do you think that the original owner mistreated the G56, and did it have the original DMF/clutch?

https://www.turbodieselregister.com...plug-on-my-G56-is-it-so&p=2299598#post2299598

 

[EMAC2]

Thanks for the reply! I will attempt to address these as best I can.

I can only speak from my experiance with this trans.
I can compare the results I have had with the G56 and the NV5600. The NV did not get near as hot as the G56 did pulling the same load.
The NV5600 was behind a lower powered truck, right? If so, then the total torque transmitted through the transmission would be less. If both trucks had the same engine, same transmission fluid, and same load then I think we would be able to compare apples to apples. Also, how did you determine the temperature and what was the type of fluid you were running?

The G56 had the magnet on the drain plug full of shavings after 20k miles.
Was that related to break-in or was that due to low level of fluid in the case? I ask because the first series of G56 transmissions had issues with supposed under-filling from the factory (noted in a TDR issue I can't recall right now) and Standard Transmission recommended the one quart overfilling as soon as they started seeing them. Something about the fill plug too low or similar.

The G56 would whin in 3rd, 4th and 6th gear after it was good and warmed up.
I haven't seen the gear cuts in the NV5600; what type of gears where they? Also, what gear lube where you using?

Also the G56 would be harder to make a smooth shift.
The early G56 models used a different sychro than the later models. The first G56's had "grooves' in the synchro's while the latter models (including the ones being made now have a fiber clutch material on the inside of the synchro assembly. I can't say for sure, but if you had an early G56 that might explain why you had trouble making a smooth shift - depending on the transmission fluid you were using

I've heard that there is a "girdle" or something that can be attached to the outside of the aluminum transmission to help reduce the flex of the case. That alone is a "red flag" to me.
That is for racing transmissions and honestly I don't see it being needed for regular heavy duty use. There are thousands of G56 transmissions out there, and I have only found four instances of the transmissions failing (granted - this is searching on-line) and they were for guys doing "tractor-pulls" and it is hard to determine from the postings if the failures were due to case flex or just plain overloading failure of the bearings themselves.

Also I hear that the new trucks with the manual trans will have the engine turned down some compared to the auto trans. For the mfg to enforce that statement, tells me to beware of the G56. That is correct. It is done to protect the clutch assembly. Theer is also quite a bit of torque management in the ECM programming done to protect the DMF. Once you change out your DMF for whatever assembly you choose, the G56 seems to perform fine IF you use the recommended trans fluid. Check out carbonitecummins for his video on the gear rollover noise link

As a side note, the DMF does appear to be Chrysler's answer to the average consumer and the noise / harshness of the inline 6 and manual transmission combination. Chrysler has to meet federal guidelines for noise on all newer vehicles (look at the little sticker posted on the driver side door sill) and the drivetrain is optimized to lower sound levels.

If anyone has any links of documented failures, I would really like to see them. I just wonder how much of this concern is related to earlier G56 transmissions and maybe low levels of fluid.

Thanks!

 

[zzman]

I had an 04. 5 with NV5600 & SB double disk 3250 clutch and a smarty jr on level 2. Transmission fluid used Pennzoil Sychromesh 2 qts over-filled with trans cool coolers. It had 375k miles when traded for the 08 w/107k miles. Never had any serious engine issues.
First thing I did was to change the clutch w/SB 3250 single disk (@110k mi), the old one was slipping when loaded. Standard Transmission did the job and I thought they changed the tran fluid at that time, whatever fluid they use? About 3 months later (at 130k mi) I changed the fluid and found magnet full of fine shavings, re-filled with the Pennzoil 1-1/2 qts over. At 160k mi last month, I changed the fluid again, same shavings found.
I had no gauges on the 04. 5 or the 08 to measure tran temp, I just touch the shifter boot to see how warm or HOT it was. I had the nv5600 so hot before that I could hardly touch the cup holder. Way too hot for my lighter to lay in. But it never acted like the G56 does when it gets hot.
I WILL be putting this Aisin to the test but the truck will stay STOCK for now, atleast til 100k. I just hope it will pull good enough, haven't worked it yet, first load is Monday we'll see what it can do.

 

[EMAC2]

Just to post up a listing of the Year / HP / Torque ratings for the transmissions from 2003. If anyone finds this incorrect please let me know. Thanks.

===================================

2003 S. O. Federal Emissions: 250HP/460lb. ft. Available with NV4500 or 47RE

2003 S. O. Calif. Emissions: 235HP/460lb. ft. Available with NV4500 or 47RE

2003 H. O. Federal Emissions: 305HP/555lb. ft. Only available with NV5600

2003. 5 The 47RE was replaced by the 48RE automatic transmission and available with the H. O.

2004 S. O. Calif. Emissions: 235HP/460lb. ft. Available with NV4500 or 48RE

2004 H. O. Federal Emissions: 305HP/555lb. ft. Available with either NV5600 or 48RE

2004. 5 (50 state legal) 325HP/600lb. ft. Available with either the 48RE or NV5600

2005 (50 state legal) 325HP/610lb. ft. Available with either the 48RE or NV5600

***** 2005. 5 The NV5600 was replaced by the Mercedes Benz G56 6 speed manual gearbox. *****

2007 6. 7L Cab and Chassis 305HP/610lb. ft with either the Aisin 6 speed Automatic or the G56 6 speed manual gearbox

2007. 5 (50 state legal) 6. 7L 350HP/650lb. ft with new 68RFE automatic and 350HP/610lb. ft with G56

2011. 5 (50 state legal) 6. 7L 350HP/800lb. ft with 68RFE automatic.

2013 350HP/660 lb-ft with G56 6 speed Manual

So the HP / Torque rating for the G56 has continued to go up as production continues. I wonder if you had an earlier G56 with the old synchro design? If you know, what were your gear ratio's?

G56
OLD NEW
1st 6. 29 5. 94
2nd 3. 48 3. 28
3rd 2. 10 1. 98
4th 1. 38 1. 31
5th 1. 00 1. 00
6th 0. 79 0. 74

Reverse 5. 74 5. 42

 

[RVTRKN]

zzman, what rpm and what gear did you climb grades at, my NV5600 never got that warm, but it was only at 19k GCVW.