HELP! Horrible growl in drive train somewhere.

[FNQGU]

Guys, looking for some direction as to the cause of a horrible growl in my drive line somewhere.

To lay out the story, while on the way home from my Cape trip last month, with about 300klms to go, I started to hear a gear-like growl (as opposed to a whine) when under load. This doesn't occur when the foot is off the accelerator and once at highway speed is difficult to detect. Anyway, I pulled up several times and checked for bearing movement, or a mudflap rubbing on a tyre etc. etc. but could find nothing.

When I got home and cleaned the truck of the 100kg+ of mud, I found a leaking pinion seal on the rear diff, and a leaking rear axle seal on the drivers side. Thinking that my rear diff oil levels must be low, I thought I'd found the cause and having run out of time I left for work for a month. On my return, I got stuck into it, pulled the rear axle out, changed the seal, re-greased the bearings, and noticed a smidge of milkyness in the diff housing oil so dropped the lot and changed it out with Penrite 85W-140.

I then dropped the tail shaft, changed the pinion seal, and checked the uni-joints for play, all good. The pinion itself seemed nice and tight, with no play. Cleaned it all up, greased the tail-shaft nipple for good luck, bolted it back up and took off for a test run. No luck! Same noise, no change.

I then removed my transfer case bash plate and had a good look around. Found a very small oil leak between the tranny and the transfer case, but nothing serious. Checked the tranny fluid levels and no worries there.

The front drive shaft felt nice and solid, turned smoothly with no sign of play in the uni-joints. As the noise is while I am in 2 wheel drive, and I have manual hubs, I didn't look much harder at the front drive shaft. Seems to be the way it should be.

I then dropped the Transfer Case oil, which looked nice and clean, and replaced it with full synthetic ATF as I had some left over from my tranny. All good, no sign of a culprit yet, however another test drive had the same result.

I then dropped the front diff oil, just for good measure, and it too was nice and clean and at proper levels.

I will probably pull the passengers side rear axle next and repack that bearing too, but I'm not confident that will be the cause. The drivers side bearing didn't have much in the way of grease in it, I would assume due to the oil leak, but it was still nice and firm. I didn't remove it from the axle either, but injected grease with a syringe (ala Parksy style) which seemed to do the job.

What else should I be looking at? Pinion bearing maybe?

[threedogs]

Its not a uni is it???

[FNQGU]

Well, on the rear drive shaft they both seem nice and firm. I didn't remove the drive shaft altogether, just dropped it from the Pinion and then gave it a bit of a feel up. Couldn't detect any play in either. Might have to completely remove the drive shaft and inspect again if there are no other obvious areas to look.

I did find that my diff breather had blocked too. I'm surmising this is why I blew two seals out at the same time, but water ingress seems very minor. I actually jacked up each side of the vehicle and made sure it all ran into the pumpkin to drain. Then put in two litres of an 80W-90 gear oil that I had spare, then dropped that out as a rinse, before I refilled with the 85W-140. I'm reasonably confident that there is no left-over water in the differential.

[nissannewby]

Pull the rear shaft out and go for a drive this will at least confirm which end up the car its coming from.

[FNQGU]

Rightio - front wheel drive only, this will be a first... You think it could be the uni's?

[nissannewby]

Rightio - front wheel drive only, this will be a first... You think it could be the uni's?

Im thinking the rear diff. My experience with unis is they will initially make noise while coasting with no load applied until they obviously get worse.

By the sounds of it you wont need to drive far to know.

[BigRAWesty]

When you did the pinion seal did you strip down the bearings and clean em up or replace em??

[threedogs]

Had a pinion fail on my other 4x4 and I had a bit of play in it.
Tailshaft moved a fair bit.

[FNQGU]

When you did the pinion seal did you strip down the bearings and clean em up or replace em??

Nope, just did the seal. There was no movement I could detect, so I took the easy route.

[BigRAWesty]

Nope, just did the seal. There was no movement I could detect, so I took the easy route.
Bearings can be tight but pitted.
Once pitted it's a quick trip to mass failure..

[FNQGU]

Ok, so I dropped the drive shaft and went for a spin. Noise is not there anymore.

Double checked both uni's though, and they are good as gold. Guess that means the diff huh? Bugger.

[threedogs]

Maybe now with the rear shaft out put the back on stands
give the wheels a turn and see if that nails t down closer.
but sounds like your diff eh did it have an auto lokka in it OOI ??

[FNQGU]

Turning the back wheels by themselves doesn't make any real noise. It seems to occur when under load, so I guess the wheels being spun by hand would be similar to just cruising...but slower...:-)

No, no locker or anything else. LSD is nice and tight too.

[BigRAWesty]

Well in this situation I think removing the tail shaft has only isolated front or rear.. or its the unis..

Everything is still turning in the diff still but has no force against it.. and you've already mentioned it only happens under load..

Unfortunately I think you gotta bite the bullet with a 50/50 stab..
It's either the uni joints, or diff..

I have read of people who have thought their uni joints felt fine, but after a rebuild it turns out they were the culprit.. you don't need much wear to upset something when it's spinning at 5000 odd rpm..

[nissannewby]

Ben do you know anyone with a patrol you could borrow their shaft from? I still think its the diff due to how the noise is occurring. Unis are cheap mate either way.

[FNQGU]

Unfortunately the mate with a Patrol is off touring in Tassie at the moment.

I can replace the uni's easily enough myself, but I think that I might need more expertise if this is going to be a diff thing. Hopefully Repco is open and has a couple in stock. I notice that only one of the uni joints is greasable too. The other has no grease nipple. Is that standard?

[threedogs]

It wasnt makig a Wrrring sound was it, any vibrations at all

[FNQGU]

Yeah, a whirring growl. A bit like a mudguard rubbing on a tyre, but only when under load.

No vibrations.

[threedogs]

Have you been doing many river crossing etc up the Cape. ??
when was the last time you gave the tail shaft a few pumps of the grease gun??
Still thinking uni

[FNQGU]

Yeah, that last Cape trip was all about water.

I've greased both the drive shafts since getting back and it made no difference. I'm just waiting for the wife to get home so I can shoot down to Repco before they shut and grab a couple of Uni-Joints. I'll change them out tonight, and then put the driveshaft back in. On closer examination, there is a slight notchy type feel in one of the uni-joints which feels like the rollers in the end caps might be worn. Not much in the way of movement, just a very slight notchiness.

If it is the Diff, would it most likely be the Pinion Bearing or something more sinister?

[threedogs]

Hopefully the pinion gear, that went first on my other 4x4

[FNQGU]

Ok, so two new Uni-Joints are in, greased and the drive-shaft is back in. The grease in the old Uni-Joints was looking a bit worse for wear, but otherwise they were fine.

Took it for a spin and the noise is still there. As speeds get up above say 80kph, it is far less noticeable. Much louder when getting from 40kph up to say 60kph whether under heavy acceleration or light acceleration, doesn't seem to matter. Going to pour a rum and think about it. I still think it sounds like a gear noise. Might be time for someone who knows what they are doing to take a look at it.

[BigRAWesty]

Bugger.
When I was reading the notchy feeling uni I was hoping that would have nailed it..
Bugger..
Well there are many bearings in the diff that can fail..
You have the pinion set, axle set X2 (left and right) and the center set X2 (again left and right).
It could be any of them.. and due to the diff brrather being blocked you can't really tell by a leaking seal like normal..
Depends on how hard you want to check.
Chock front wheels, lift rear diff..
Start and stick in drive and get the wife to load the brakes just enough to allow the wheels to spin..
Grab a long screw driver, place the tip on the diff case near where the bearings are and place the handle just I front of your ear lobe..
If a bearing is notchy you'll hear it..

[Kimbo63]

How many km did you travel with water in your diff ? Good read here on bearing failures
http://www.knowyourparts.com/technical-articles/what-causes-bearing-failures/
Also some water crossing tips here good info
http://www.pps.net.au/4wdencounter/4wdtech/water.html
Cheers Kimbo

[FNQGU]

Thanks Kallen, I'll give that a go.

Kimbo, I reckon I did at least 300klms, but that was when I first noticed the noise. It could have been much, much further. Like 2000klms or so.

[Kimbo63]

Ouch that will probably do it i would say at least a set of bearings and hope that no damage is done to the gears
But it will be also be good to strip the lsd to clean the contaminated oil out of the discs ect.
Do you run breather extension ?

[threedogs]

And you have no up/down play at the pinion gear end at all ???

[FNQGU]

Ouch that will probably do it i would say at least a set of bearings and hope that no damage is done to the gears
But it will be also be good to strip the lsd to clean the contaminated oil out of the discs ect.
Do you run breather extension ?

Yeah, hoping for the best.

No, the breather isn't extended. It had also come off the crossbrace and was blocked with shit as well. Lesson learned there!

TD, I gave it a shake when I had the drive shaft off and there was no noticeable play in it. There was a bit of slackness when I turned it before it would engage and turn the wheels but not much at all. To me it felt pretty good.

[threedogs]

did you notice any metal when you drained the diff oil?
so now its either pinion ,, diff bearings or wheel bearings

[FNQGU]

The magnet on the drain plug had a light fur coat this first time I dropped the oil, BUT yes, I did find two small fine metal bits this afternoon. Very thin and sharp, like slivers. I found them on the plug today when I re-flushed with diff oil again, just to double check that no more milkiness was in the oil after a bit of driving around.

Tomorrow I am going to try and pull the cover off the diff and have a look. Not sure what I should be looking at, but will give it a crack anyway and see what can be seen.

Hopefully this is narrowing it down. I was told that a trade-in reconditioned LSD would be around $780 if I wanted or had, to go down that path. Is that ball-park?

[FNQGU]

Diff Specialist had a listen today - seems to indicate that the Pinion Bearings will likely be the problem, but won't know for sure till the Diff is stripped.

[Kimbo63]

How did your truck go with the new tranny cooler has it sorted all your overheating problems?

[threedogs]

Diff Specialist had a listen today - seems to indicate that the Pinion Bearings will likely be the problem, but won't know for sure till the Diff is stripped.

Thats good to hear

[FNQGU]

We'll see I suppose! Hopefully this doesn't cost an arm and a leg.

@Kimbo - yep, all seems to be going well now with the heat issues. It is 36 degrees ambient here today and no issues (besides the bloody diff) when doing the range run with aircon going full tilt. Was a new larger engine oil cooler too, not a tranny cooler. Tranny was sitting at 81 degrees, oil temps at about 86 degrees. My engine watchdog packed it in, and I haven't bothered to replace it, so not 100% sure on thermostat bolt temp, but if those other two indicators are anything to go by, then all is well.

[nissannewby]

Did you leave to be stripped today or is it going back at alater date? Or are you going to remove it yourself?

[FNQGU]

Monday now. I'm going to just drop the vehicle off to them. They have a lapping machine etc. and pretty much do most of the diff work in town so should be able to sort it.

[FNQGU]

Pinion Bearing was on its way out, and the Pinion was wearing as a result, but nothing too major. Apparently the Ring Gear was ok. New bearings and a clean up of the Pinion Gear is what they are reporting was done today. Test run still to be done once it is all back together this arvo. Will pick it up tomorrow.

Thanks everyone for the opinions and advice. Hopefully this has it all sorted!

[mudnut]

Good to see you got it sorted, how much has it set you back?

[BigRAWesty]

Good outcome..
Hopefully not the expensive

[FNQGU]

Just under a Gorilla from the Diff blokes, plus the cost of Diff Oil, Axle Seals and the Uni joints that I did myself.

After driving it around a bit today and doing some highway speeds, it feels like there is a vibration somewhere that wasn't there before. It's hard to detect, but at speeds above 80kph I feel it through the seat. A bit like an imbalance or a very faint whirring feel somewhere.

[BigRAWesty]

Bugger.. the only thing I can think of is maybe the drive line is outta ballance a bit now??

[FNQGU]

Yeah, was thinking along the same lines. It doesn't feel major, but something isn't quite right. Will see what tomorrow brings.

[mudnut]

It will probably be the unis out of sync or phase.

[FNQGU]

So, how does one check that? I just greased em up a little extra in each of the end caps and stuck em in, then made sure all the retaining clips bedded properly.

[mudnut]

What this guy said; http://www.patsdriveline.com/index.php/home/faqs.html.

Before taking any drive line components off they should be marked so they can be reinstalled and be balanced and in phase.


https://www.youtube.com/watch?v=9unvQ-xf_XA

[threedogs]

Did you replace the tail shaft exactly the way it was removed , its not 90 Degrees out is it ???

[FNQGU]

Hmmm, ok, I am learning things.... Didn't mark them, just pulled them off and put new ones in. When I put them back I lined them up with the red-dirt marks, so I reckon they could be 180 degrees out as opposed to 90 degrees, if anything. Sounds like I have some mucking around to do. I'll get back under it and see how I go.

[threedogs]

Yeah 180 out my bad, sometimes ppl use centre punch marks so you can re assemble them the same as they were pulled out.
Seeing you mentioned a wrrrring sound Ill still say the tail shaft, nearly there hang in, lol