problems after fluid change, please HELP....

[xman111]

Hey guys, decided to do some fluid changes today in hopes of making my 2004 Pathy last a little longer. I went to Nissan and got 9L of Nissan DMatic ATF fluid (for transmission and tranfer case) and 5L of Penzoil 80w90 Gear plus for the front and rear diff.

I drained and replaced the auto transmission fluid with Nissan D Matic and everything was fine. I then came home and replaced the front and rear diff with the Penzoil that the parts guy told me to get. I took the truck for a drive around the block and everything sounded fine. I switched it into auto AWD and still seemed ok. When i switched it into 4 High, i started getting grinding and terrible noises. The truck actually almost came to a full stop (from just a roll) because it felt like it was binding. When i switch back into 2 wheel drive, the car drives normally. It actually makes a big clunking when switching between 4 wheel and 2 wheel as well with the switch.

I thought it either had to be filled too much (but can't go past the fill hole for obvious reasons), not enough fluid (it's at the drain hole), or the wrong fluid in the front diff. Does anyone have any input to try to help me out? I was out there all day instead of spending the beautiful day with the wife and kids, nightmare.

Do the front and rear diffs get the same gear oil even though the back is a LSD? I decided not to do the transfer case yet because I didn't want to add another variable to the mix.

Here is the stuff I put in.

https://app.box.com/s/dyxhqtp88xzf29uzf8jxwjh3pp5qcyjk

[atraudes]

Assuming the gear oil you used is synthetic, there's no problem there. Using non-synthetic oil would only cause chattering while cornering, not the audible hurt you described.

The front and rear diffs use the same fluid. As long as you filled it up to the hole, you're fine. If the problem only happens when shifting into 4WD, then you have a problem with the transfer case. The reason I say that is because the front diff is locked to the wheels, so when the wheels are turning, they turn the CV joints, differential, and front driveshaft so that when you switch to 4WD, the transfer case can simply attach itself to the already rotating front mass. All that to say if it was a problem with the diff, you'd hear it as soon as you start driving, regardless of which mode you're in.

However, if you have manual hubs everything I just said isn't true. Manual hubs will disengage the front wheels to prevent the front drivetrain from spinning. Switching it into a 4WD mode with the manual hubs disengaged leads to all sorts of nastiness like what you described.

My guess is that if you don't have manual hubs (an aftermarket option, not OEM) there's a problem with your transfer case. Changing its fluid may do the trick, but it's more likely there's a mechanical issue. How recently was 4WD working properly?

It's not a surprise that AWD didn't cause a problem. The system only engages the front wheels when it senses they're needed, like when the rears start to lose traction.

I'm not familiar with how the fluid in the transfer case is emptied or filled, but if you are, take a look at the level and quality. The transfer case and transmission use the same type of fluid, so I'm wondering if you needed to do something to the transfer case when you did the transmission.

[atraudes]

Actually after some more reading, the transmission and transfer case fluid should be independent. Have a read through the TF-Transfer section of the FSM. There's some troubleshooting steps you can follow and things to look for. MA-Maintenance describes checking the level, draining, and refilling.

[xman111]

hey guys, thanks for the responses ATR. I changed the transfer case fluid and pretty much everything went away. It had a couple problems disengaging from 4 wheel to 2 wheel but a couple times around the block fixed that. It is weird, I didn't think it was the transfer case because I never touched it, everything seemed to happen after changing the gear oil in the diffs.

It's weird though, all the fluids were very clean, not sure why the transfer case would have done that, if it is in fact the transfer case.

[atraudes]

Well, cheers to it being fixed