Outer Limits 4x4 Board

Hi all,

As the heading suggests, my 75 series has slowly (over time - 12 months) developed a clear and, now very noticeable, whine from what appears to be the rear end of the ute.

I'm posting this topic with the hope that, once again, the wealth of knowledge shared by the members on this forum will save me any more trouble.....I've spent months and months trying to figure this one out....

The ute is a standard 75 series ute, 1HZ, now with 50,000 km on the clock, immaculately cared for - inside and out. The whine is audible only at around 1600 RPM, slightly noticeable nearer to 2000 RPM, and only in 2nd, 3rd and 4th gear. Over the past weekend I suspect that the noise is now becoming audible in 5th gear too. It should be noted that the noise will only remain audible for as long as what the RPM are maintained, and maintained under load at that. In other words - driving uphill at 1600 RMP in 3rd gear it sounds like there is a band saw being used in my tray. If I increase the RMP or decelerate the noise instantly disappears.

From within the cab, even with the windows up, the noise is clearly coming from the rear of the car. Ive checked every bushing, joint, bolt, nut...anything I can grab....for any signs of ware or free-play....but no luck. I feel it may only be coincidence, but the noise only became noticeable after replacing the exhaust system, but having checked every gasket, joint and bend, sadly however, I'm beginning to think this noise might be associated with the rear diff.

Without being told the obvious (to check the rear diff), are there any other suspected causes for this problem. More to the point, does anyone have information to share with my that would be worth following up on before I take the rear end out of the daily driver.

The rear diff oil was changed 10,000km ago, any came out clean. The ute does not tow and is only occasionally used as a 4wd (not for recreational purposes). Occasionally (if going camping etc.) I will fit a set of 33 inch Baja MTZ tires. However, when they fun tires come off and the regular split rims for daily use are put back on, the noise is as clear as ever.

Any, and all, comments and questions are welcome, please help me to solve this problem. I would be more than happy to photograph any part of the car that might help with identifying probable causes.

Thanks in advance,

Mitch

So you got married 12 months ago and the whining has been getting worse ever since?? Common problem, can't be solved just put up with it, you could try to muffle it but eventually it will get even worse.



Possibly a heat shield vibrating on/around your exhaust under a certain load? get someone to kick your tailpipe while you inspect/listen under your car.

Have you jacked your car up, put the rear diff on stands. Then engaged drive (2WD) to be able to get good close listen to your rear diff?

Hahaha good one, made my day. Could throw money at it and see if it helps

In all seriousness though, thanks for the reply.

There aren't any heat shields on rear-most sections of the landcriuser exhaust system. I have thoroughly inspected the exhaust system though, and it seems to be fine. The sound has more of a mechanical tone to it (if that makes any sense at all), very much similar to high powered saw. I have often put the rear end on jacks and used the choke to run the rear end (in 2WD) at different speeds, but the noise is only there under load, so this doesn't do much to reproduce the sound it makes.

Does this sound in any way similar to problems with drive shafts perhaps? Should I be looking at something other than the diff as the sound is only occurring at a particular frequency hence a tendency for this problem to be related to something other than the 3rd member itself. Are there any other components within the rear diff housing that could produce this sort of noise other than a diff? I only ask as I don't expect to have trouble with a well looked after landcruiser diff with only 50,000km.

Thanks again,

Have you tried greasing your tailshaft points to see if the noise changes? If not, grease the universal joints but particularly the slip joint and see if the noise dissapears or changes pitch.

suggestion,may be wheel bearings

Thanks Ray and Stan,

I hadn't considered a wheel bearing as of yet. Is it typical of a worn bearing to make a noise only a certain frequency? I'll pull the wheels off tonight and have a look.

Ray, I've had a good look at the tail shaft thinking this was my problem from the start, but I have never greased the slip joint. I'll give it a crack tonight and see if does me any good. Would the uni's make this sort of noise without exhibiting any very obvious ware?? they look what I would call "ok", but then again I'm no expert....

I'll post up with some results,

Cheers

def sounds rear diff cw/p to me

be careful not to over grease the slip joint, too much grease can cause vibrations. 4-5 pumps from the grease gun should be heaps

if Uni joints are worn they will tend to cause a vibration more so than a whiining noise. If they are suspect they will tend to make a noise when you back off the throttle and load is removed. best way to check the uni joints is to unbolt the tail shaft and rotate the uni joint in each direction, it should rotate smoothly in every direction, if not time for a change. it can be hard to tell their condition with the tail shaft bolted in IMO. If uni's are suspect greasing them might give temporary improvement, but best to change them

Sounds a lot like the rear diff, try dropping a small amount of oil out of the drain plug to see if there is any metal in the oil.