ATF Change in Response to Grinding Noise

My 2007 3.0 Junior has been making a slight grinding noise when moving for probably 500 miles. It started far from civilization so I couldn't address it immediately. I was mis-informed about how to check the transmission fluid and thought I was still full. I noticed a leak and wetness under the tranny but couldn't tell exactly where it was coming from. Once I got home I grounded the vehicle pending more info. Besides an existing glow plug short, there are no additional OBD codes.

I got the transmission dip stick and will be checking the ATF as soon as I can get the vehicle to a level spot to do work. Assuming it's low, here's my plan.

It seems that two of the most common leaks are the electrical connector plug and the pan gasket. I've ordered the plug and a full ATF change kit with the gasket, filter, and fluid from Europarts SD. I've never done a ATF change, so it's likely due. Rather than trying to diagnose the problem further, it seems like the best path is to simply change the fluid, filter, seal, and plug and see if the problem goes away. It seems like a popular choice to change the fluid in the torque converter at the same time, which also seems like a good idea since things have been under lubricated for too long. I'm using the FSM and Dr. A.s guide, along with youtube for instructions. It's clearly more work than an engine oil change, but mostly the same idea. Dr. A. also suggests checking and cleaning the speed sensor while I'm in there.

https://sprinter-source.com/forum/showthread.php?t=2476&highlight=transmission

I have a few questions:

1) Is the 8 quarts of fluid I got with the kit only for the tranny, or also for the torque converter?
2) If I decide to clean the sensors, what should I clean them with?
3) Should I really do the sensor check the first time, or just wait until next time when I have better sea legs? There tranny seems to be mostly behaving itself.

I'm hoping this will resolve the problem and things haven't gotten too ground down. It will probably be pretty obvious if any of the relevant gaskets are blown. If the leak persists afterward, it will probably be time to take it into Freightliner for further expensive diagnosis, something I would obviously prefer to avoid, no matter how cute their service manager is.

Any additional suggestions? I'm nervous because it's my first time, but it looks like it shouldn't be too bad, and I can't afford this vehicle if I can't do this kind of routine maintenance myself.

Bitmaster.
A grinding noise is not going to be fixed by a fluid change. I would think it is more likely the drive shaft centre bearing. If you grease it and it improves the situation you will know. If you clean the speed sensor in the transmission all you need is to wipe it with a rag. Eric.

Eric Experience said:

Bitmaster.
A grinding noise is not going to be fixed by a fluid change. I would think it is more likely the drive shaft centre bearing. If you grease it and it improves the situation you will know. If you clean the speed sensor in the transmission all you need is to wipe it with a rag. Eric.

Click to expand...

Thanks Eric! That sounds easy to find and try. I see endless threads on what to do about it, including incompatibility between the 2007-2008s and later NCV3 models.

I was thinking if enough tranny fluid came out the gears would start to grind. Definitely worth trying lubing the center bearing first, and checking the ATF with the dipstick.

Will report back.

I should also mention that this has been accompanied by a popping noise when turning the steering wheel. It happens every rotation or two in both directions. I checked my power steering fluid reservoir, and it is full.

Since the automatic tranny fluid seems to be ok, I'm happily willing to accept the problem isn't with the transmission.

I tried lubricating the center bearing using 3-in-1 oil. Accessing the bearing was easy from the front end, and I lubed both circles thoroughly. There was some kind of cover on the back, so I lubed along the one seam there. It's *possible* that it improved, but I can't be certain.

The noise starts as a low, quiet grind and tracks drivetrain rotation, not engine or tranny speed. It's still audible coasting at low speed in neutral. As I slowly accelerate, it moves into more of a whining scrabble. At about 50 MPH, it's pretty hard to hear.

It seems like lifting the vehicle is in order both for this and the steering pop, but for different ends for each problem. Since mine is a 2-wheel drive, if I life the rear wheels off the ground I can have someone spin the shaft while I'm listening for noises, right? I realize it's dangerous, should keep the wheel straight, etc. Then for the steering thing, I boost the front wheels and have someone move the wheels while I listen for popping?

Bitmaster.
Yes jack it up on solid stands and then turn the wheels, try one side then the other in case it is a wheel bearing. Eric.

So we have success on both items!

After jacking up the rear to spin the driveshaft, I discovered a shiny wear-ring around the shaft near the center bearing. The metal shield in that area has lost a nut on one corner, and was brushing up against the driveshaft, causing the noise. The center bearing is ok. All I need to fix it is whatever nut or clip fits that thread, and I'm good. Rarely have I been so happy a repair was so simple! I also have a much better understanding of the driveshaft system after all the research I did, so that's one less part of the vehicle I'm afraid of.

We then jacked up the front to look into the steering, and the click is definitely occurring between where the steering column goes through the firewall from below into the cab. All the universal joints look ok, and it seems like Eric called it, it's probably some kind of bearing that shepherds the column through the firewall. Europarts SD doesn't seem to carry that part, so I'll have to look elsewhere. Obviously I want to fix it, but it doesn't seem super critical. As long as I get to it soon, it's just annoying. I bet getting in there to fix it is going to be a pain.

Thanks for the help! This was all looking super expensive and scary when I started, but really all this stuff is small fry.