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2008 CRD NAG1 problems

4K views 39 replies 6 participants last post by  giacomo.m 
#1 ·
Hi all,

I have this Nitro 2.8 CRD which has the following error codes, P0741 and P1731 and recently I noticed some strange shifting behavior
are they serious problems ?
thank you

Giacomo
 
#5 ·
Update

I checked the automatic fluid with the special tool dipstick with gearbox in "D" and "R" with a temperature of 156 ° F and the oil level measurement on the dipstick is 55/60 m so I would say that it's okay, but when I replaced it in the container I measured 3.5 / 4 liters ......... why?
also the oil is very black and around the magnet in the oil pan there is a lot of iron or aluminum filings
tomorrow I fill the gearbox with the usual 5 liters of ATF + 4 and the new filter and let's see if anything improves ....
I also checked for any contacts or breaks in the electrical wires that come out of the connector on the gearbox with metal parts nearby but it seems to me that everything is ok, but in your expert opinion, by replacing the body valve can I solve my problem or do I have to replace the entire automatic gearbox ?
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thank you

Giacomo














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#10 · (Edited)
check fluid level in 'P',
chech fluid temperature in 'D' or 'R',
3. Actuate the service brake. Start engine and let it run at idle speed in selector lever position "P". 4. Shift through the transmission modes several times with the vehicle stationary and the engine idling 5. Warm up the transmission, wait at least 2 minutes and check the oil level with the engine running. Push the Oil Dipstick 9336 into transmission fill tube until the dipstick tip contacts the oil pan and pull out again, read off oil level, repeat if necessary. Fig. 185: NAG1 Transmission Fill Graph Courtesy of CHRYSLER LLC 6. Check transmission oil temperature using the appropriate scan tool. 7. The transmission Oil Dipstick 9336 has indicator marks every 10mm. Determine the height of the oil level on the dipstick and using the height, the transmission temperature, and the Transmission Fluid Graph, determine if the transmission oil level is correct. See Fig. 185. 8. Add or remove oil as necessary and recheck the oil level. 9. Once the oil level is correct, install the dipstick tube cap. hot or rotating parts. NOTE: The dipstick will protrude from the fill tube when installed.
 
#12 ·
Hi Nitrogen
thank you for the correct automatic transmission oil check procedure
I have already checked inside of the harness/transmission connector,I sprayed an electrical contact cleaner / flux and it looks like they are in working order
but what do you think about the difference in liters between those measured with the dipstick and those actually removed ?

Giacomo
 
#13 ·
the difference in quantity is most likley due to you checking it in "D",
but don't worry, drain old fluid, refill with 5l of new fluid and new filter (very important) ,
take Nitro for a drive get everything to operating temperature then check fluid level just to be sure its ok,
and see how she/he drives,
 
#15 ·
because you found alot of metal filings stuck to the magnet i would replace the transmission,
the NAG1 transmission is supposed to be very good with few problems,
 
#16 ·
The transmission control module is programmed to immediately place the transmission into neutral ifP0730 or P1731 codes are set. These codes indicate that the transmission experienced an unknown orincorrect gear ratio. Placing the transmission in neutral prevents potential catastrophic failure. When thisoccurs, the transmission will remain in neutral until the vehicle slows to 29 Km/h (18 mph).
 
#17 · (Edited)
forget what i said in post #15, i would definately try and clean the valve body, or if you find a cheap valve body replace it,

i found this on another dodge forum:

There is a known issue with a 3-4 shift flare or Neutraling out on the 3-4 shift. In most cases this event is accompanied by a P0730, P1731, P0734, and/or P0733 Incorrect Gear Ratio codes. The cause of this event is ferrous or Aluminum debris in the 3-4 Shift Pressure and/or 3-4 Holding valves. Rather than replacing the VB;
1.) Remove the solenoids, leadframe assembly, and bolts securing upper to lower valvebody
2.) Lift upper housing off the VB and turn over. No need to clean the lower housing.
3.) Remove the steel endplate covering the all the 3-4 valves.
4.) Remove the 4 valves and flush out the bores and valves with a solvent such as mineral spirits. Contamination is known to be very small. Hold the housing vertically and flush the bore out generously. Flushing over filter paper (coffee filter) will allow you to observe the debris.
5.) Re-assemble the VB and re-install to roadtest.
6.) Only if the valves are still sticky after the flush or if the 3-4 shift issue persists, should the VB be replaced.
LOP 21-95-01-51 provides 1.2 hours for this repair.
 
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#25 ·
forget what i said in post #15, i would definately try and clean the valve body, or if you find a cheap valve body replace it,

i found this on another dodge forum:

There is a known issue with a 3-4 shift flare or Neutraling out on the 3-4 shift. In most cases this event is accompanied by a P0730, P1731, P0734, and/or P0733 Incorrect Gear Ratio codes. The cause of this event is ferrous or Aluminum debris in the 3-4 Shift Pressure and/or 3-4 Holding valves. Rather than replacing the VB;
1.) Remove the solenoids, leadframe assembly, and bolts securing upper to lower valvebody
2.) Lift upper housing off the VB and turn over. No need to clean the lower housing.
3.) Remove the steel endplate covering the all the 3-4 valves.
4.) Remove the 4 valves and flush out the bores and valves with a solvent such as mineral spirits. Contamination is known to be very small. Hold the housing vertically and flush the bore out generously. Flushing over filter paper (coffee filter) will allow you to observe the debris.
5.) Re-assemble the VB and re-install to roadtest.
6.) Only if the valves are still sticky after the flush or if the 3-4 shift issue persists, should the VB be replaced.
LOP 21-95-01-51 provides 1.2 hours for this repair.
 
#18 ·
Does anybody know how to do a complete flush of the oil using the same procedure flushing the return line and do a full exchange, not only the oil in the oil pan?

Only changing the oil in the pan means that 3 litres of old oil remains in the circuit.

Suggested reading

 
#19 ·
I have done flushing twice.
*Drain the oil, remove the pan
*Replace filter, fit the pan
*Fill with at least same amount of oil as drained
*Disconnect oil cooler return line
*Connect clear hose to return line and put another end to empty canister
*Start the engine and shift between gears- this will pump out oil- pump out about 2 litres
*Add same amount oil you pumped out
*Start engine again- pump out more
*Repeat till oil is perfectly clear
*Check and adjust oil level

When cleaning valve body upgrade with these
 
#22 ·
Great information Jan. That's the missing link for my transmission oil change (y)(y)
The best practice would be to have an intermediate connector, e.g. a modified banjo bolt to redirect the return flow to a canister.
 
#24 ·
oops .. do not understand how this part look like. Any visual linformation available?

I read your document. This is the way Daimler drains the return oil by a simple "connector".

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Thank you very much, Jan!
 
#29 ·
don't like the large amount of iron filings on the magnet, normally indicaites something has worn down, if you can find a cheap valve body then i would give that a try, but i would imagine you can find a complete transmission for €500,
how many KM's on your Nitro ?,
 
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