KZJ78 Manual Gearbox whining

[rollingrufus]

Gidday,
I am new to the forum, so thanks in advance to all the lads with the seemingly unending wealth of knowledge out there!

I have a 1994 Prado KZJ78, which I bought to replace an ageing Surf. I love the truck, very capable.
Recently I have noticed a significant whine coming from the gearbox, which only presents itself in 3rd, through to 5th. 1st and 2nd have no noise. I have not changed the oil (next on the list) as of yet but a quick look shows it is clean. Gear changes are fine in all gears. The whine gets more intense and seems to react to acceleration. I have replaced the transfer case oil which was muddy brown in colour, and had filings on the fill cap.
Where do I look for model numbers of the gearbox? Is it cheaper to rebuild or replace? Anybody know of a good source for a reconditioned gearbox?
Thanks again in advance lads I really appreciate it.
Benny.

[axel]

Hi Benny, GBox will be r151f. Itl say it on the plate in engine bay next to trans/axle. FYI Axle will be g284 from memory, maybe 285 if it's got factory locker?

[oldblue]

Just a thought,Could it be the centre shaft in the transfer box, as these if warn on the thrust side of the shaft will make a wining sound on acceleration.

[Petemcc]

Just a thought,Could it be the centre shaft in the transfer box, as these if warn on the thrust side of the shaft will make a wining sound on acceleration.

My uneducated guess would be transfer case. Oldblue can you explain this a bit more? Is it something you have seen before and is it something to be overly concerned about?

Cheers,
Pete

[oldblue]

Because of the rotational thrust of the centre gear it tends ( roller bearings ) to wear thru the hardening of the shaft ( one side only ) This also upsets the matching gear contact faces. Usually is noisy on acceleration but quite on deceleration. Not a good thing when there may be metal practical's that could stuff the other bearings.

[mudlva]

Maybe better in the long term to pull the box out and get bearings etc replaced before it lunches itself all together. Sounds like the transfur is due anyway. Least that way you know you are starting with a nice fresh units
Imho

[mudmike]

Transfer case can be done in place, crap job but did mine, gear box is a major. have you tried putting transfer case in N and see if it goes away. may help pinpoint the issue.
All the bits are available as kits from Don kyatt in Manukau.
Good luck

[oldblue]

The only issue I had with doing it in place was the input seal, because the seal tunnel only has a chamfered edge on the outer side of the T/C to guide the seal in smoothly, from the outside, If pushing the seal in from the inside of the case just be extra careful that you do not damage the outer part of the seal, on the sharp edge as it goes in.

[rollingrufus]

Awesome thanks guys I will get it all sorted ASAP. Im currently away with work, and having just got back from 6 weeks work in the middle east the old girl has taken a back seat!
Thanks again lads I really appreciate all the info!

[rollingrufus]

Lads!! Hope all is well...
Just been doing a bit of research between shifts.
So the gearbox out of my Prado is the same as a Hilux gearbox?? (R151F) Does that mean the transfer case could also be one out of a same year Hilux if I was to replace?
If I was to rebuild myself, are there any special tools I would need? And is it something that, if you havent done one before dont bother?? Im a self taught mechanic, by the looks so far it might be best left to the pros!
Lastly, does anyone know of a good place that might do rebuilt exchanges on gearbox/transfer cases?
Thanks lads, Chrissy coming up soon, gotta get the old girl running sweet for the fishing trips onto the beaches!

[mudmike]

no different transfer box, the prado has a big pin 70 series case, means you can run a pto off it.

[rollingrufus]

no different transfer box, the prado has a big pin 70 series case, means you can run a pto off it.

Ah yes true, so if I purchase a rebuild kit it will be the one for a 70 series landcruiser is that right?
Is that you in the pic mudmike? What sort of flying do you do mostly? Ive just started myself.

[mudmike]

yes its me when I lived in queenstown, only do a little coastal stuff now

[Clint]

If I was to rebuild myself, are there any special tools I would need? And is it something that, if you havent done one before dont bother?? Im a self taught mechanic, by the looks so far it might be best left to the pros!
!

Just did mine, Full weekend's work (incl a few mods to fit aftermarket low range gears) but not too bad a job. I pulled the whole gearbox etc (easy with a hoist & trans jack, not so much without) Needed some 2 arm med sized pullers to get some off the bearings etc off the shafts, press to install the new ones. Would be doable with more basic equipment if you had the required bush mechanic skillz.

I think it was this site where I found the manuals: http://daemon4x4.org/portal/downloads.php?dcid=17&p=3

You basically have to disassemble the transfer to take it off the gearbox, then reassemble it on the gearbox, so it's not like some vehicles where you could just unbolt it & give it to someone to rebuild, they'd need to do the whole job. That's also why I pulled the gbox off to do mine, by the time you've got the transfer off you're 90% of the way to having the gearbox out anyway, & it's way easier to work on with the box standing on end next to the workbench rather than in the vehicle. Removing/installing the whole gbox-t-case assembly is a really 2 man job though, even with a hoist & trans jack.

There were some variations to the 'split-case' 70 series transfer box over the years so check with the seller when you buy the kit.

Cheers
Clint