6 speed Transmission problem

[lcarleton]

While on the road, I had a worsening problem with noise from the transmission. After stopping in Salt Lake City and having it pulled it looks like it is rebuildable with a bearing kit. Question is: The machanic said there was a problem in the 5600 trans with the stock fluid level was so low that one needed to install a nipple and 90 on the fluid fill/check hole to actually overfill the trans to keep it oiled in all towing condition. Only have 127,000 miles on the truck and tow less than 10,000 pounds regularly. Has anyone else heard of this issue with this unit?

 

[HBarlow]

While on the road, I had a worsening problem with noise from the transmission. After stopping in Salt Lake City and having it pulled it looks like it is rebuildable with a bearing kit. Question is: The machanic said there was a problem in the 5600 trans with the stock fluid level was so low that one needed to install a nipple and 90 on the fluid fill/check hole to actually overfill the trans to keep it oiled in all towing condition. Only have 127,000 miles on the truck and tow less than 10,000 pounds regularly. Has anyone else heard of this issue with this unit?

Yes, it is a well known, often discussed, common problem. The design of the transmission case will allow lube starvation of the major bearing assembly if fluid is allowed to get slightly low or if negotiating a steep downgrade.

My NV-5600 got a little low on fluid due to a very slight leak around the top cover seal and I spent a very unpleasant day in stop and start traffic on an LA freeway pulling a heavy fiver while traffic was backed up due to a fire in the hills. It wiped out the bearing in my transmission that day.

Standard Transmission and Gear in Ft. Worth, TX, a TDR advertiser, rebuilt the transmisson at 302k miles. I think the transmission would have lasted another hundred thousand miles or more if not for my allowing fluid to get slightly low then stressing it that day in LA traffic. Standard overfilled my transmission when they reinstalled it and advised me to always overfill it slightly.

 

[lcarleton]

update. New transmision. Bearing wear caused wear on main shaft gear wear and cluster. If the nose starts, get it fixed.

 

[FATCAT]

While on the road, I had a worsening problem with noise from the transmission. After stopping in Salt Lake City and having it pulled it looks like it is rebuildable with a bearing kit. Question is: The machanic said there was a problem in the 5600 trans with the stock fluid level was so low that one needed to install a nipple and 90 on the fluid fill/check hole to actually overfill the trans to keep it oiled in all towing condition. Only have 127,000 miles on the truck and tow less than 10,000 pounds regularly. Has anyone else heard of this issue with this unit?

What year truck is yours?



I have a 2008 with the G56 manual. I thought the low oil level due to the filler plug was solved in 2007? At my next oil change I will have the machanic make sure the transmission fluid is filled properly.



Thanks for the heads-up.

 

[HBarlow]

LCarleton,

Your post is unclear because it is posted in the Gen III cab and chassis forum but apparently has a NV-5600 transmission according to line three of your post.

What year is your truck and which transmisson does it actually have? I assumed it has the older now replaced NV-5600 because the problem is not uncommon in NV-5600s and you used the term "5600" in your original post.

The post will confuse some Gen III cab and chassis owners like Fatcat above who is concerned about his G-56.

I think your post is in the wrong forum.

 

[dan.poitras]

Did the 2nd gens have a six speed?

 

[HBarlow]

Did the 2nd gens have a six speed?

Sure. The NV-5600 was first offered in 2000. Bill Stockard owned one. I had a 2001 HO/six speed and know lots of people who also own one or previously owned one. The HO/6 speed combo was also offered in 2002.

 

[ACoyle]

I PM'd L Carleton and asked for truck info. When I get it I will put the thread wher it goes.

Andy

 

[rbattelle]

Yes, it is a well known, often discussed, common problem. The design of the transmission case will allow lube starvation of the major bearing assembly if fluid is allowed to get slightly low or if negotiating a steep downgrade.

Are you sure about this? The NV5600 has been around a long time, and until the 3rd gen forums I never heard anyone blowing one from low lubrication levels.



And even within the 3rd gen forums I don't recall this being very common. Maybe I haven't been paying attention?



On the whole, there aren't very many NV5600 failures. If having the fluid level slightly low would cause a failure, I'd think we'd be hearing about it constantly.



I'm not questioning your experience, but what is "slightly" low?



Ryan

 

[MMeier]

Are you sure about this? The NV5600 has been around a long time, and until the 3rd gen forums I never heard anyone blowing one from low lubrication levels.



And even within the 3rd gen forums I don't recall this being very common. Maybe I haven't been paying attention?



On the whole, there aren't very many NV5600 failures. If having the fluid level slightly low would cause a failure, I'd think we'd be hearing about it constantly.



I'm not questioning your experience, but what is "slightly" low?



Ryan

Been covered here many times Ryan. "Slightly low", by "most" peoples terms is about 1-1. 5 qts. I have 10 qts in my latest one... with 2 fast coolers attached to it.

 

[lcarleton]

a 2004 3500 with a 6 speed

 

[lcarleton]

Sorry about the lack of good information so here it is. It is a 2004 3500 4 wheel drive non-dually with a 5600 transmition the mechanic said was only used for 2 years. 127,000 miles on the truck.

 

[HBarlow]

Are you sure about this? The NV5600 has been around a long time, and until the 3rd gen forums I never heard anyone blowing one from low lubrication levels.

And even within the 3rd gen forums I don't recall this being very common. Maybe I haven't been paying attention?

On the whole, there aren't very many NV5600 failures. If having the fluid level slightly low would cause a failure, I'd think we'd be hearing about it constantly.

I'm not questioning your experience, but what is "slightly" low?

Ryan

My NV-5600 began a grinding noise after the towing experience I reported in my earlier post. At the end of that day if I launched and drove across a parking lot in second gear at slow speed, say 15 mph, and approached the edge of the parking lot where I put the clutch in and allowed the truck to roll to a stop the transmission made harsh metal grinding noises.

I was in LA. I nursed it back home and my young mechanic friend added some fluid. I don't remember now but I think he added maybe 1/2 quart to one quart. The noise continued so I made an appointment and took it to Standard Transmission (TDR advertiser) in Ft. Worth, TX. It had 302k miles on it. They pulled the transmission, disassembled it, found a worn out bearing assembly, some mild wear on 6th gear, very mild wear on the synchronizers, and reubuilt it. The tech who rebuilt the transmission and others at Standard overfilled it and advised me to always overfill it. It was they who told me it was a common problem.

I don't know if the main bearing assembly in my NV-5600 simply wore out, was damaged by slightly low fluid level, or if it was worn and slightly low fluid level accelerated the problem. All I really know for sure is what the people at Standard Transmission told me, allowing the fluid to get a little low will cause early failure.

I had heard about the recommended overfill for some time. I think it was common knowledge.

 

[WStephens]

2008 would not have a NV5600 they stopped using them in 2005 and are no longer made. It was replaced with the G56 and it had problems with being under filled and were put on hold until the problem was found and then the late 2005 trucks were then avaliable with the G56 again.

 

[CumminsPower98]

I have about 305k on my NV5600 upgrade and its doing fine so far. I have read about the low oil level as well and have overfilled by one quart at least once. I ran mine low once but was not aware of it until later. I knew I had a slight rear seal leak but didn't fix it right away. When I did finally get around too it I was real surprised to find that most of that leak was transmitted into the t-case, which was way over full. I run the same Amsoil MTF in both boxes so no problems there. I was towing RVs at the time this happened. I don't know if this caused any damage or not but so far I have no noises and good shifting.

 

[CROW]

Read someplace that one way to overfill the NV-5600 is to fill from the top by removing the shifter someway. Other than that method, how do you overfill?

 

[MMeier]

Read someplace that one way to overfill the NV-5600 is to fill from the top by removing the shifter someway. Other than that method, how do you overfill?

I would park sideways on an incline... driveway, curb, etc. , and fill through a PTO cover bolt on top... above fill plug.

 

[Curious Dave]

Problem: I was going 80 when my NV5600 locked up. The clutch was completely destroyed and the trans was seized. It also broke a couple of teeth.

Cause: I had a dealership service the trans and when they did they did not put enough oil in the trans. I had the FAST coolers on and they only put in 5 quarts. Normally this would have been the correct volume, but with the coolers they should have been able to get at least 6 maybe 7 in.

When the trans was replaced they only found 4 quarts in the trans. It wasn't leaking.

With labor, rental car, trans, and misc. costs it came to @ $5k.

Cure: I got it back and found a leak. I decided to service the trans to find the leak and found that the idiot that swapped the trans had cracked my lexan covers on the FAST coolers. I bought some 1/4" aluminum plate and made my own covers. I filled the trans with 8 quarts after I pulled out my console and shifter.

No more problems.

Lesson: Verify mechanics work before leaving the garage. Dealership or otherwise.

 

[HBarlow]

Problem: I was going 80 when my NV5600 locked up. The clutch was completely destroyed and the trans was seized. It also broke a couple of teeth.
Cause: I had a dealership service the trans and when they did they did not put enough oil in the trans. I had the FAST coolers on and they only put in 5 quarts. Normally this would have been the correct volume, but with the coolers they should have been able to get at least 6 maybe 7 in.
When the trans was replaced they only found 4 quarts in the trans. It wasn't leaking.
With labor, rental car, trans, and misc. costs it came to @ $5k.
Cure: I got it back and found a leak. I decided to service the trans to find the leak and found that the idiot that swapped the trans had cracked my lexan covers on the FAST coolers. I bought some 1/4" aluminum plate and made my own covers. I filled the trans with 8 quarts after I pulled out my console and shifter.
No more problems.
Lesson: Verify mechanics work before leaving the garage. Dealership or otherwise.

That's an expensive experience. I think you're saying the dealership refused to make it right.

One minor point. Few dealerships employ what we used to call mechanics.