'06 with a G56 and about 181K on the ticker all hauling miles 50% loaded/50% empty. Truck has started with a grinding noise I guess you would call it. It seems to be mostly under acceleration (not even heavy acceleration) and it does it in all gears except 5th. It is much easier to hear in 3,4, and 6th. Shift into 5th and the noise quiets down extremely. It may be present just a touch but not near what it is in the other gears. The truck also seems to have a slight hesitation occsaionally noticed in 6th gear like someone was turning a head wind on and off. Just kind of a gentle surge effect. Not sure if this is related. Anyone provide any help?????

 

Best thing you can do first is to check the oil....

 

Oil or tranny fluid?

 

Your G56 takes ATF (oem recommendation), I just called it oil... I would check the level. Use a 14mm hex key to open the plug on the side of the trany. The oil level should be right at the opening of the plug. I would imagine if you started having hard shifting/grinding lately, your oil level MAY be low. It could possibly be something else, but,
Easy things first....

 

Start with the simple stuff......very true!! Haven't seen any leaks though. Where would it disappear to?

 

Hard to say....but noises like that just starting to happen is usually indicative of lubricant loss...possible as well that it came with a low level shipped from the factory and over time with your towing...well, you get the idea, right?
I would certainly check it out.

 

I hate to tell you but you need a rebuild soon. I had same issue with mine, I made all the way from north FL to MN in 5th gear at 55mph towing 18k of cargo.

Have a shop look at it before you get stranded or worse you blow it up, it's cheaper to have rebuilt with a good core exchange than pay $ 1000 extra for a new case.

 

Valv.....that was the news I was hoping not to hear! Just drained the fluid and changed it. Fair share of metal shavings in there. What ended up being the problem with it?? I am in WI so curious where in MN you had your work done? Pricing?

Anyone else with these same symptoms??

 

how come you guys ho tow dont relize that you need to change the fluid in the tranny. when i was running the old nv's i would change it every 60k or 6 months. with the g56 's i'm running i change it every 40k or 6 months because i dont think the atf can handle the heat from the weight. if you change the fluid regularly the tranny will last. have over 700k on 2 trannies in my big trucks because we change the fluid often

 

That's a good point Rich, especially when the ATF fluid is so cheap, charging it should be no problem. I just changed mine at 6000 miles but I did it because it's the first oil on a new transmission. It's hundred bucks in oil but still cheaper then rebuild sooner.

 

I change it every 50K and still having an issue. Guess its the luck of the draw sometimes.

 

dont feel bad the one in my early 07 only lasted 10k before it started going bad, they think it came from the factory with bad fluid. it didnt make any noise just hung in rverse all the time and shifted like crap. they finally replaced it after 6 mo and another 40k it was fubared inside

 

My 06 lasted 30K before it started making noise. Bad growl in 4th-5th and 6th in the lower rpm range. Two days ago it started leaking oil out the front seal so it has been parked until it goes to the shop tomorrow AM. Unfortunatley I am hoping for new trans instead of a rebuild but we will see.

 

dont hold your breath i had to fight with dc on mine and they said it had to be over 70% damaged before they would replace it otherwise they rebuild

 

Yeah, I heard the 70% thing too. We shall see. I have had to threaten this dealer with getting a lawyer once before. They know I am tired of it and they generally don't mess with me now.