Is it CVs or a diff problem?

[sea-dog]

Howdy,

First post in the forum.

I'm a complete newbie to 4wds. I have just bought a very stock 93 Mav wagon 4.2 NA diesel manual trans, Manual hubs. - I still call it a Patrol regardless of the stickers.

Can someone diagnose what my front-end problem is from the symptoms.
My guess is either CV, hub, or diff.

The following tests all done on my front lawn.
I didn't lock the hubs and put her in 4WD on solid ground as I understand this is a No-No.

Hubs unlocked - 2WD - No problems.
Hubs unlocked - 4WD - (just crawling along at idle, going straight ahead) - There is a hesitation, then clunk once every 3 - 5 Metres at a guess. It feels like climbing over an obstacle about 4 Cm high.

Both hubs locked - 2WD - Similar hesitation and clunk, but both smaller, approx every 2 Metres.

Left hub locked, Right hub unlocked - 2WD - No clunk.
Right hub locked, Left hub unlocked - 2WD - No clunk.

So does this sound like CVs or diff or something more sinister?

Cheers, Ross.


Sunnybank, Brisbane.

[MudRunnerTD]

putting the car in 4wd without locking the hubs will not engage the front diff just the transfer case i think.

You can drive the car in 4wd as long as you dont lock the hub and not cause any damage. very strange symptom i reckon. CV's will be a crunching or clicking noise and more likely to be when you try and turn or load them up, definitely not at idle speed.

Reading the post again it is clear that it only happens in 4wd. i am thinking more the transfer case than the front end but others may have a better idea?

[stalker]

if I had to guess I'd say hub. Sounds like its not engaging properly. Or maybe its been put back on wrong? Should be that it would make a Clunk sort of noise if one is locked and the other is Not. Would be where I would start. if ya don't know what your looking at pull them off and take it to a mechanic ask there opinion.

Anything past that pushes the price up quite quickly.

To ad what mud just said, I had a similar problem which only happened in 4wd. my hubs were rooted. But did the whole lot to be sure. Also found a bad axle and checked the diff. But only the hubs would have made that problem on mine. And really the starting place.

[90MAV]

Since there is a quieter "clunk" when in 4WD and hubs unlocked doesn't that rule out the hubs??
My guess would be something in the crown wheel in the diff as this would result in a noise every 2 metres or so.
I'd get the diff checked first. But that's just my opinion

[Iron Horse]

Originally Posted by sea-dog

Howdy,

First post in the forum.

I'm a complete newbie to 4wds. I have just bought a very stock 93 Mav wagon 4.2 NA diesel manual trans, Manual hubs. - I still call it a Patrol regardless of the stickers.

Can someone diagnose what my front-end problem is from the symptoms.
My guess is either CV, hub, or diff.

The following tests all done on my front lawn.
I didn't lock the hubs and put her in 4WD on solid ground as I understand this is a No-No.

Hubs unlocked - 2WD - No problems.
Hubs unlocked - 4WD - (just crawling along at idle, going straight ahead) - There is a hesitation, then clunk once every 3 - 5 Metres at a guess. It feels like climbing over an obstacle about 4 Cm high.

Both hubs locked - 2WD - Similar hesitation and clunk, but both smaller, approx every 2 Metres.

Left hub locked, Right hub unlocked - 2WD - No clunk.
Right hub locked, Left hub unlocked - 2WD - No clunk.

So does this sound like CVs or diff or something more sinister?

Cheers, Ross.


Sunnybank, Brisbane.

To be a full test , you will need to lock the hubs and engage 4X4 and do the same again , you wont hurt it (unless it's already broken).

[sea-dog]

Just checked in 4WD (High & Low range) hubs engaged.

Still makes the slight clunk every 2M approx.

Forward and Reverse - No difference.


What it feels like is a small object being caught between meshing gears, and once it climbs over/compresses that object, all is fine until it comes around again.

[sea-dog]

I was thinking I might disconnect the front driveshaft from the transfer case and repeat my front lawn tests.

That will show whether the transfer case is the problem, or if the problem exists between the diff and the hubs. (obviously I hope its not the transfer case end.)

I will probably lose a bit of diff oil if I have to pull the yoke out, but that's easy to top up. Perhaps I should do a full change of oils anyway.

Once I have the location of the problem, I can proceed in that direction.

Thoughts?

[Adoom]

is it mainly the left hand side that feels like it climbs up?

[limited]

you dont have to have the car running.engage your hubs, select a 4wd gear, jack it up so the wheels are off the ground, and turn the rear tailshaft.It'll make it easier to pick the noise if nothings running, and its easier to climb under a car thats not running on gear...
It almost sounds like a bent axle or hub assembly..

[sea-dog]

Originally Posted by Adoom

is it mainly the left hand side that feels like it climbs up?

Well, the sound seems to be coming from the left side of the vehicle.

But I've learned not to trust my sense of hearing when trying to locate the source of a noise in a vehicle.

From the drivers seat - just about the whole car is to the left.

What's your line of thought?

[sea-dog]

Originally Posted by limited

you dont have to have the car running.engage your hubs, select a 4wd gear, jack it up so the wheels are off the ground, and turn the rear tailshaft.It'll make it easier to pick the noise if nothings running, and its easier to climb under a car thats not running on gear...
It almost sounds like a bent axle or hub assembly..

I'll have to go and get another pair of axle stands to lift all 4 wheels off the ground.

Maybe I should get some decent quality ones, rather than the pressed steel crappy chinese cheapies that I've got.

I'd hate to be underneath the patrol if they decide to sag a bit.

When riding the clutch at idle, to get over the "hump" I have to let the clutch out a wee bit more, then she clunks and moves forward again.

With the clutch fully out at idle she'll just clunk and keep on rollin' along.

[sea-dog]

Originally Posted by MudRunnerTD

putting the car in 4wd without locking the hubs will not engage the front diff just the transfer case i think.

You can drive the car in 4wd as long as you dont lock the hub and not cause any damage. very strange symptom i reckon. CV's will be a crunching or clicking noise and more likely to be when you try and turn or load them up, definitely not at idle speed.

Reading the post again it is clear that it only happens in 4wd. i am thinking more the transfer case than the front end but others may have a better idea?

Happens also in 2WD with hubs locked, so I'm hoping the problem is somewhere inside the diff housing.

[ITS A FORD NOT A NISSAN]

even easier is to just crawl under the car and turn your front drive shaft by hand , out of 4wd , and hubs unlocked first , turn the shaft and see if there is noise or binding , then lock one hub one one side only , then turn drive shaft , then do the other side

i think its the front diff but process of elimination still needs to be done

[sea-dog]

Originally Posted by ITS A FORD NOT A NISSAN

even easier is to just crawl under the car and turn your front drive shaft by hand , out of 4wd , and hubs unlocked first , turn the shaft and see if there is noise or binding , then lock one hub one one side only , then turn drive shaft , then do the other side

i think its the front diff but process of elimination still needs to be done

Sounds much easier, thanks.

I'll try that tonight after work if its not raining.

Cheers, Ross.

[Danaz]

To check the CV's jack the front end up then lock the hubs in. Put the transfer in 4WD with the vehicle in gear, engine switched off (this will stop the diff rotating). Spin 1 wheel and the other will spin the opposite way, rotate the steering to different positions whilst spinning the wheel. If you get and noisy / really hard spots CVJ is probably the culprit.

[sea-dog]

I tried ITS A FORD NOT A NISSAN's suggestion from post # 12.

I had the motor off, transfer case in neutral, gearbox in neutral and hubs unlocked and wheels on the ground.

I couldn't turn the front shaft.

Im thinking more and more its the diff.

The patrol was parked on the front lawn which is the terrortory (spelling intentional) of several green ant nests.

I didn't fancy laying around under the truck waiting for several of the little buggers to climb down my neck and go to work on me. Most Qlders would agree with me.

I will pull the boat out of the garage and park the truck in there before I start undoing shafts and the like.

Then once and for all I can determine where the problem lies.

If it turns out to be the diff - it gives me an excuse to have a Lokka fitted at the same time as repairs.

From what I've read here they seem quite OK.

The next thrilling instalment in the saga may have to wait for Sunday, as the missus wants to try out her birthday present on saturday morning. (New surf rod)

I'll keep the patrol in 2WD (hubs unlocked) for the trip to Bribie Island or thereabouts and see what we can stir up in the way of fish.

Thanks to all for your valuable assistance. - I will no doubt be bugging the forum with many, many questions as I get into the whole 4WD experience.

Cheers, Ross.

[GQtoy]

sounds like you might have a tail shaft uni seized up.

[Iron Horse]

Originally Posted by GQtoy

sounds like you might have a tail shaft uni seized up.

That would do it .

That would explain the ramp over effect as the bent seized joint went over center .

[chester]

Mine does roughly the same but in reverse it feels to bind up then let clutch out more and few more revs, it clunk's then free's up. i put it down to the parkbrake.

[sea-dog]

Well, I parked the Patrol in the garage and jacked the front wheels off the ground.

Hubs locked, 4WD, 1st gear, engine off. So the diff couldn't spin. I spun the right wheel forwards - the left spun backwards. No noises, no shudder etc. I turned the steering full lock - both ways, and repeated the spinning. Once again - nothing unusual.

So the problem isn't the CVs or the hubs.


I dropped both ends of the front drive shaft. The universals are a little tight, but nowhere near enough to cause the clunk.

More testing.....

With both hubs locked and front axle on stands, I spun the right wheel by hand.

The left wheel stayed still and the diff yoke spun until there was a clunk from the diff.

The diff stopped spinning and the left wheel started spinning.

I then reversed direction and the left wheel stopped again as I spun the right wheel for several revolutions. The diff was spinning until the same clunk happened and the left wheel started up again.

It seems there is something quite wrong with one tooth on the crown wheel. The pinion rotates smoothly until it reaches the same spot on the crown wheel.

Time for a new diff centre.


Next question: Should I be able to turn the front of the transfer case when both transfer case and gearbox are in neutral and front drive shaft disconnected? It wouldn't turn more than a fraction. It felt like it was in gear.