Gearbox + water = oh f*&k

Hi Gents, I think I've got a major prob.

I've been trying to track down a whine in the ute for about two weeks or so now. Was convinced it was a boost leak because I had just finished sorting out a split hose, thought maybe another one had gone. Any way I fixed that but the noise remained.

The missus drove the ute into the shops Saturday morning with me in the passenger seat and I noticed the noise was coming from the centre of the cabin rather then the turbo side and only when she was in 5th.

So I went straight to Cheaper Auto spares and I got some new gearbox oil and a oil hand pump. About lunch time today i pulled my finger out and started changing the oil.

Didn't make it far but, I checked to make sure the filler plug would come undone first and to my surprise it came undone nicely, but behind that filler plug was a nasty mess of muddy/oily water mix. OH F*&K! Removed the drain plug and in total about 6.5L of what looked more like muddy water then oil came out. Yep 6.5L when there should have only been 5.1L of oil.

Left Gearbox to completely drain while I checked the transfer box, oil drained out of it in perfect condition thank f*&k for that. So i refilled both boxes and took it for a test drive, and yes the whine is still there.

On a side note, i checked the magnetic drain plug on both boxes and there was hardly any metal shavings, less than a 1/4 of a teaspoon in total of a really fine metal on both of them, kind of a good sign I guess?

So does anyone have any ideas on what i should be looking at doing? Rebuild? taking the gear box out is do-able but as for rebuilding it, I wouldn't even try that. Does anyone do exchanges?


I think the water got into the box about 4 weeks ago when I sunk the Ute up to the bullbar at ollera, I thought i got away with only having to strip the inside of the Ute out. I've done about 1000kms since it went under and the noise started about 2 weeks ago.

Any thoughts would be awesome,

Thanks,
Bait-fish.

Rear diff, centre bearing, wheel bearings (front/rear). You should check your oils after any significant near sinking.

Basically, check everything that rotates. As for it only doing it in fifth... It might be speed related? To be in fifth, you'd be hooking at 70+

mate i would drain the oil a couple more times, and even add some gearbox treatment like NULON or one of those and see what happens then.
If you have had that much water then you wont get it all out in just one or two changes.

If that doesnt work then i would call the guys at "Nissan 4X4 wreckers" in vic. here is link just incase.
http://www.niss4x4.com.au/

My Fiances Mazda 323 developed a whine in 5th gear shortly after the gearbox secretly spilled its oil. It was driven like this (without my knowledge) for about a week before seeing the mechanic. The leaking issue was rectified and new oil added to the gearbox, after that the whine stayed around for about a month then suddenly disappeared.

If it was me i would just refill the gearbox with fresh oil and maybe change it again a few weeks later and see if it all comes good in time. No point lashing out on another gearbox if you might not have to.

thanks gents,

i put some of the nulons in both boxes when i changed the oils. Will deff change the oil again going to let it run for a bit just to mix the new oil through everything first.

As for speed, I tried it in a few gears, normally in 5th by 70km/h, so I revved fourth out to about 80km/h and no noise until I changed into fifth.

The noise is only there while I'm accelerating as well, as soon as you take the load off, the noise stops. I feathered the accelerator on and off to check and the noise comes on and off with the gas and only when in fifth

blacknav, i rang my old man tonight and asked him about it and he said prety much the same thing with a car he once had. I normally take his word for near gospel when it comes petrol cars, but diesels he's a little less sure on. i guess gearboxes are similar petrol or diesel. lets hope for best i guess.

Hi Baitfish,
If your ute has carried heavy loads or towed freuently I would say there's a fair chance of it being the chatter in the gearbox from the leyshaft bearing. 5th gear is weak and shouldn't really be towed with (especially not uphill). I think the drive in 1st and 4th gear is straight through the gear box (1:1) ratio and therefore strongest but someone else may be able to explain this better. If you remove the gear lever surround you should be able to tell if the sound is coming from the gearbox or not. If you hear the sound in 5th, not fourth and quieter in 3rd and 2nd but not 1st gear then I would say leyshaft bearing.

yeah I'm not sure how much towing my ute has done prior to me owning it. i brought it at about 170,000kms and its just past 190,000kms with no towing in that time. the sound is def coming from the gearbox and i can only hear it in fifth. Gets louder the faster you go.