Help! Expensive 4x4 Noises?

[TwoBoard]

Been to Bures today, brilliant conditions and excellent weather.

The kids and I were thoroughly enjoying our day until -

Climbing a tricky, muddy incline, in L4 2 were nearly at the top, wheels starting to lose grip when bump and then a clonk. Reversed a little and gave it some to get over the summit and made it but..

Now while in 4x4 i get a few clonking noises as the Surf moves along and the rotation of the driveshaft/axles does feel jumpy/knocking, no jolt or noise while engaging, but does jump when disengaging.

2x4 there is no noise, no knocking and all appears fine.

Anyone experienced anything similar, got any ideas what bit I've broken and does it sound expensive?

[TonyN]

You need to jack it up and give the wheels a spin, chack all the front drive stuff, driveshafts, prop shaft, diff etc, for play.

[Vagrant No2]

Does sound like the front diff has lost some teeth , a few Surfs seems to have done this over the last year .

[TwoBoard]

And if it is a toothless front diff, whats the cure?

New Diff?

I saw there is a secondhand one on ebay, are all transmission bits and pieces the same? ie 2.4 = 3.0
I have a 94' KZN130.

[TonyN]

And if it is a toothless front diff, whats the cure?

New Diff?

I saw there is a secondhand one on ebay, are all transmission bits and pieces the same? ie 2.4 = 3.0
I have a 94' KZN130.

Yeah, but make sure you get the right gear ratio in the diff.

Check the cheaper stuff first like Prop shaft UJ's, and CV's in the front shafts.

[dirtydog]

mine jumps and messes around in 4x4, fine if im in the mud though
never been able to find out what it is but missing teeth seems to fit the beaviour of mine actually but my surf has always been like it!

[TwoBoard]

Inspection is being delayed at the moment as weather is naff.. (and I havent cleaned the truck yet)

But while sitting in doors staring at i have been hypothesising..

The knocking/grinding noise is only apparent when 4wd is engaged and is rhythmic probably with the rotation of something.
The wheels have manual locking hubs, which as I understand disengages them from the half axles extending from the diff, when in 2wd with these unlocked there is no noise. Great!
Similarly, in 2wd with the hubs locked there is no noise. Great!

Question: Now if the half axles are rotating with the wheels, does this mean the differential is also rotating?
Or does the differential only operate when power is trasferred to it?

Question: If the differential is rotating is the front prop shaft rotating?

My theory being, if the differential is rotating and there is no noise then it is not a broken diff and the noise is further back up the transmission.
If the front prop shaft rotating with the diff then it is even further back.

In the 4wd transfer box maybe.

Please can anyone put me straight on any of my theories or questions?

[TonyN]

With your hubs locked and in 2wd, the drivers side shaft will only turn the spider gears in the diff. passenger side shaft is disconnect via the ADD.

You want to try it 4wd with hubs unlocked and see if it makes a noise.

I've never in 20 years of wheelin' Toyotas seen a broken t/case, even with a V8 and 35" tyres.

Weakest part of the front drive set up is the CV's, then the hubs, and then the UJ's. Check all those parts first.

The pinion nut could have loosened, if the front wheels get a huge shock loading, the crush coller that sets the pinion pre-load can get squashed more, making the nut loose, causing the pinion gear to float in and out on the ring gear. But normally on the rear only suffers from this, normally a CV will explode first on the front.

[TwoBoard]

Have now noticed the mud appears 'wet' on the drviers side of the diff.
A spray of sticky fluid.
I guess something is leaking from somewhere.

Does this add weight to any diagnosis?

[TonyN]

Have now noticed the mud appears 'wet' on the drviers side of the diff.
A spray of sticky fluid.
I guess something is leaking from somewhere.

Does this add weight to any diagnosis?

They often seep oil from the seal in the side, If the CV was shot it would make the shaft vibrate, and the seal won't work properly.

The shaft goes into one of the spider gear inside the diff, could be a diff issue, but always start with the cheap, easy stuff first.

[TwoBoard]

So.. took Friday off work as the weather was good and got under the car.

Had a good look round but not a lot of physical damage externally as I can see. Needs two new CV boots, one of which i had ordered so managed to replace the drivers side. This was the cause of the 'wet' mud, it had been flinging CV grease about.
Jacked up the rear, and rotated the wheels, both appear ok, hubs and diff are quiet, was a little play (maybe 1/2inch) in rotating wheel from forward to backward before the other starts to rotate. I don't think that is too concerning, I guess. Replaced diff oil, all ok.

Then the front, drained the diff oil. Hmmm! Lots of metal bits came out with it,
nothing that would be recognised as gear teeth, but worrying nonetheless.
Prop shaft and UJs appear ok and quiet.

Did a quick a service and replaced all fluids and filters. All running ok since.

4WD still making a noise when engages. Don't know if I should be worried still, it appears to engage just sounds a bit disconcerting..

Any views, comments, advice or spare diffs welcome?