Subtle grinding from G56 transmission.

[PVasilauskis]

Noticed a subtle grinding noise in the cab. It's fairly subtle, I have to turn the volume down on the radio in order to hear it. I found a similar thread but it had no resolution What I've determined so far:



At a dead stop in neutral, such as at start up:

Clutch released (pedal down, engine running) no noise.

Engage the clutch, noise starts.

Release the clutch, noise slows to a stop.



Coming to a stop:

In gear, clutch released, noise slows to a stop with vehicle.

In neutral, clutch released, vehicle usually stops first then noise slows to a stop.

In neutral, clutch engaged, noise continues even while vehicle stops until clutch is released to shift into gear.



Cold seems to increase the noise, it wasn't until last fall when the temperatures came down that I noticed it. When I first start out on a cold morning I can really hear it. After the engine's been up to normal operating temperature for a while I can still hear it but it sounds noticeably quieter. In fact after I first noticed it, it went away for a while but that was probably when we had a warm streak in the 70s.



It's an '06 with 29,400 miles, some (<1000 miles) towing a 9k 5th wheel. At lights I don't sit with my foot on the clutch, in fact that's probably why I heard it because I sit with the clutch engaged at the light.



Since day 1 it's always been harder shifting when cold but not hard if you know what I mean. Even before I noticed the noise I was thinking on going with a synthetic ATF-4 (amsoil) to see it that's makes a difference in the cold. Now I'm wondering if that would help this or if I really have something mechanically wrong.

 

[SRadke]

Have you tried changing the oil? Start there and see if there's any metal on the magnet.

-Scott

 

[PVasilauskis]

Well I changed the fluid today. When I pulled the plug, this is what it looked like. (you can click on an image to go to a larger view)



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Very scary because it reminded me of when the kids were studying magnets in school and I took some nails to a course wheel on the bench grinder then ran a magnet around the base of the grinder. But it's not like it's filings but more like a thin gray paste. I took a paper towel and cleaned it off and it more or less smeared off, there was no grittyness to it.



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So is this just normal wear products I'm looking at? She has only 30,330 miles on her.



I refilled her with Amsoil ATF. Only took her around the block but she seems to shift smoother, especially 2 -> 3, still a bit of a clunk when going in at times but it feels like it slips in nicer. Temps are up around 45 so the real test will be how it feels when it's down in the teens though I might have to wait 'till next year for that.



As far as the noise goes, it's still there. I'm beginning to think it's normal gear noise that's always been there I just never noticed it before and now that I have, I can't help hearing it. Unless of course what I found on the magnet is not normal and I do have real problems.

 

[Motorhead]

Soundsd like input shaft bearings. Are you still under warranty? It is normal to have some metal fuzz on a magnet but that looks like more than I would want to see.

 

[rbattelle]

Is it a grinding or more of a whine?

Ryan

 

[Andersonville]

DMF Issues?

 

[SRadke]

That is more metal that I expect to see at 30k but no big pieces is a good thing. What I see there doesn't scare me a lot. Looks like you pull it hard a lot. Heavy trailer?

 

[PVasilauskis]

The noise I guess would be described as a grinding. If you took your radio and tuned it between stations so all you got was static, then turned the volume way down till you can barely hear it, that's kind of what it would sound like. When I first heard it I believe I was driving around with the radio off. I noticed it just before I came to a stop and that it stopped when I stopped moving. My first thought was I was hearing a thin layer of corrosion on the brake rotors rubbing against the pads since it appeared to stop when motion did but then I found it came back when I released the clutch and was at a stand still. That's when I went hummmmm.



I bought the truck Feb '06 so I'm just out of the warranty period, yeah kickin' myself in the butt for not realizing it was only a 3yr / 36 month warranty not a 5yr / 60 month. #@$%!



We just got the trailer last summer and had it out maybe a half dozen times all fairly local within a half day drive. It only weighted ~9,600 the day we picked it up. (hit a Cat Scale coming home from first picking it up) So we're talking maybe ~10,500 loaded out, not really what I would consider heavy.



I know if something really is wrong it ain't gonna cure itself. But it drives and tows just fine. Since I'm out of warranty what are my options? I'm figurin' on the wait and see approach. See if the noise gets worse or she starts to get hard to shift. If it lasts with no problems change the oil again in another 30,000 and see if the magnet is hairy again. Maybe start putting some cash aside for a fix.



I'm guessing transmission work is gonna be labor intensive and thus $$$. Any guesses on how much? Would this be something to trust to a dealer or a shop?



As far as the DMF, isn't that outside the interior of the case, outside of where the ATF lube is, so I don't see how it would attribute to the stuff I found on the magnet or are you simply suggesting it could be a source of the noise I'm hearing?

 

[HBarlow]

If you have excellent hearing and are in a quiet environment you can probably hear the routine sounds of precision machinery rotating and gears meshing on any transmission if you are listening carefully but the way you are describing the sound is a little more than routine. It could have a bearing going bad although with low mileage and light use it shouldn't be bad. I haven't heard of a G-56 failure like that.

Have you thought of crawling under the truck with a mechanic's "stethoscope" with the metal probe you place against running machinery? You could move the probe around and possibly hear better and determine the source of the noise. If you do, make sure to use the parking brake and block the wheels for safety.

I had the NVG-5600 rebuilt in my '01 at 302,000 miles by Standard Transmission and Gear in Ft. Worth, TX. A TDR advertiser. I think the total bill for parts and labor with a complete new clutch assembly was about $2100. W/o the clutch is was about $1800-1900 for the rebuild.

I would take it to a trusted mechanic familiar with transmissions and ask him for an opinion. He may put your mind at ease.

 

[Andersonville]

The DMF could be the source of the noise as the DMF is usually what goes first. My DMF went at 104k just out of the powertrain warranty of course. What Harvey said, take it to a trusted mechanic and let them check it out or just drive it until it breaks. I would put the Mopar ATF back in it just in case. In any case, if it is a little noise you can't hear with the radio on, you probably have a long way to go before it is a problem. The G56 IS a medium duty truck transmission. I have 339K on mine and I use the Mopar ATF and I frequently pull 13-15k 5th wheels and goosenecks. When the DMF went out I had it replaced with a South Bend Con OFE unit which is very noisy. The G56 also gets noisy when it gets low on fluid and gets hard to shift into 1st and reverse. Mine got 2 qts low once,thats how I know. Good Luck

 

[Regcabguy]

The DMF could be the source of the noise as the DMF is usually what goes first. My DMF went at 104k just out of the powertrain warranty of course. What Harvey said, take it to a trusted mechanic and let them check it out or just drive it until it breaks. I would put the Mopar ATF back in it just in case. In any case, if it is a little noise you can't hear with the radio on, you probably have a long way to go before it is a problem. The G56 IS a medium duty truck transmission. I have 339K on mine and I use the Mopar ATF and I frequently pull 13-15k 5th wheels and goosenecks. When the DMF went out I had it replaced with a South Bend Con OFE unit which is very noisy. The G56 also gets noisy when it gets low on fluid and gets hard to shift into 1st and reverse. Mine got 2 qts low once,thats how I know. Good Luck

Concerning your OFE noise... I spoke to Peter awhile ago and he's got an OFE that he claims is nearly indistinguishable noise-wise from stock. To quote Peter,"You won't even know it's in there. " He's also got a quieter DD coming too.

 

[PVasilauskis]

I would put the Mopar ATF back in it just in case.

Why would you do that?

 

[PVasilauskis]

BTW, what is the size of the hex fitting on the fill and drain plugs? I've been using a 1/2" which works but is obviously too small. Is it a metric size?

 

[Andersonville]

Doesn't the powertrain warranty go for 100k? Or is it just the motor that goes to 100k?
Try a 17mm or 14mm hex wrench on the plugs.

I was told that the ATF 4 was synthetic.

"Concerning your OFE noise... I spoke to Peter awhile ago and he's got an OFE that he claims is nearly indistinguishable noise-wise from stock. To quote Peter,"You won't even know it's in there. " He's also got a quieter DD coming too. "

When it wears out I will look into replacing it. My Con OFE is still going strong and Peter told me that the noise was no indicator of early failure.

 

[RShipp]

The Mopar ATF4 is the only fluid recommended for the G-56 according to the owners manual. Not saying that any other synthetic doesn't do the same thing, but that requires a bunch of research. May just be Mopar trying to keep the business.

 

[JeffBecker]

I have an 06 g-56, and have not seen any more than a little bit of gray film on the plug. It has 116,000 on it,and on its 3 change with Royl Purple. As for the noise,it's hard to hear any little noise over the DD clutch.

 

[PVasilauskis]

Well I fixed my noise problem and you are not going to believe what it was.



The AMSOIL ATF I replaced the ATF 4+ with has a unique smell to it. Two + weeks later and I'm still smelling it every time I get in. Now I had replaced the engine oil with Rotella-T at the same time and we all know that causes a petroleum smell for a few hundred miles so I figured the ATF smell was the same way and would die away shortly but it wasn't. So this weekend I went in search of the source of the ATF smell. I ended up taking the shifter/cupholder console apart and found the heavy rubber boot that comes up from the transmission case and fits snuggly over a plastic tube on the shifter had slide down off the tube opening a 1" or so gap directly down into the case. I pulled that boot up over the tube and put it all back together. Could it have been that easy? Apparently so. Got in it this morning and there was still a wiff of ATF but nothing like it was. Start up, let out the clutch... . silence! The real test was going to be getting in after work after it had been sitting out in the sun all day. Got in and barely a wiff, probably just what's in the seat fabric and just needs to air out.



Big thing is no more noise. Of course now I feel like an automotive hypochondriac. I don't feel that bad because the wife heard it also.



There still is a little concern over what I found all over the magnet when I drained the case. (See previous post with pics) I'll probably change it out again in another 30K and see what's on it then. But I have to tell you, the AMSOIL ATF definitely showed an improvement in smoother shifting, especially in the morning with temps in the upper 30's.

 

[RShipp]

There is an orange boot under that. You have to take the black boot off the floor board to see it. Might want to check it. They last about 70,000 miles and they tear.

 

[PVasilauskis]

There is an orange boot under that. You have to take the black boot off the floor board to see it. Might want to check it. They last about 70,000 miles and they tear.

I have less than half that mileage. Seems it's back to normal now but if the smell doesn't completely go away, I'll pull it up and check that boot.

 

[big61fourby]

I first changed mine around 25k... magnet looked very similar to yours. The particles were very tiny, they just looked bigger. Replaced with Amsoil universal ATF. Changed again 50k, not as many particles, went back with Redline C+ ATF. Amsoil and Redline gave a little better shift performance than factory fill; couldn't tell much difference between the two. I also added Geno's filter kit... seemed to catch some of the junk.