Thread: Intermittent crunching noise

I'd check the clutch master and slave for leaks or low fluid first. Probably not it, but it's the problem you want it to be.

Originally Posted by steveG

I've had a nasty sounding noise occur in the County a few times in the last couple of days.
Sounds like a couple of gears crashing for a split second then disappears.
My wife noted that it seems to happen more when going around LH bends, but its not something that I can reproduce at will.
Its also not always the same intensity/loudness. Sometimes loud and harsh, and other times its only just audible.
It doesn't seem directly related to a particular gear, engine revs, roadspeed etc. Its happened cruising at 100km/h in 4th, and also in either 2nd or 3rd under brakes. Also happened once coasting up to the lights with the clutch depressed. I don't recall it happening under hard acceleration though.
The noise appears to be coming from the main gearbox or bellhousing area (ie forward of the driver, but I'm wary of the strange ways that noise travels.
Gearbox is an LT95.

The only other thing of note is that a couple of times in the last week when I've reversed out of a carpark its felt a bit jerky - like a slowly juddering clutch. Both times I would have been turning slightly at the same time as I was reversing. Unsure if its related, but maybe worth mentioning.
Apart from the scary noise there are no other bearing/gear noises or anything strange - its driving great.

My main concern is that there's going to be one final BIG bang as the gearbox or transfer grenades, so I'm guessing its a case of start by dropping the oils to check for debris, then keep going from there - ultimately pulling the gearbox and checking the bellhousing/clutch area if I cant find anything else wrong.
The other thing I'll do is to pull the starter off and check it in case its something like the starter pinion contacting the ring gear.

Anyone had a similar problem, or got any suggestions as to what it might be or things to check?

Steve

check that transfer case lock (centre diff lock) is not engaged on sealed roads

I would be suspicious of the low range gear on the centre diff having loose bolts.
Have a look at Stirlings post of his stage 1 and its failure.

Steve, I would check that the handbrake linings are not overadjusted and binding, this will give a backlash /jerky type noise.

Thanks for the ideas...

Originally Posted by abaddonxi

I'd check the clutch master and slave for leaks or low fluid first. Probably not it, but it's the problem you want it to be.

All good there.

Originally Posted by 87County

check that transfer case lock (centre diff lock) is not engaged on sealed roads

CDL definitely not engaged. Engages when selected offroad and the light is working OK so I know its not engaging on the road.

Originally Posted by Bearman

Steve, I would check that the handbrake linings are not overadjusted and binding, this will give a backlash /jerky type noise.

The handbrake is rubbing verrrry slightly on the drum. Not enough to feel if you jack up a rear wheel and turn it by hand, but just audible as a regular rubbing sound as it turns.
I'd have thought that this would cause more of a backlash/release/backlash sort of issue, but I'll back the adjuster off slightly just in case....

I drained the transfer oil to check for signs of carnage but didn't find any. Its quite a bronze/metallic colour, but only very fine particles and they stay in suspension in the oil. A couple of small flakes, but nothing that looks abnormal.
Tomorrow night I'll remove the bottom cover from the transfer and have a look inside since the oil is out anyway.

Originally Posted by djam1

I would be suspicious of the low range gear on the centre diff having loose bolts.
Have a look at Stirlings post of his stage 1 and its failure.

Yes, I've seen Stirlings photos of center diff destruction
I made sure when I put the center diff back together that all the bolts were cleaned, loctited, and torqued correctly. I also marked them with paint and there was no sign of any movement when I had the speedo housing off about 3000k's ago to sort out the drive gear ratios. If the low range gear is loose enough to be moving around I'm hoping I should be able to see it with the cover off the transfer case.

Steve

Check your wheel bearings.. I had these symptoms once before and that is what is was.

My guess would be either a CV joint or a wheel bearing. Neither are likely on a County, unless the item in question is dry or lubricated with mud instead of oil.

But diagnosing noises without hearing them is likely to be a bit hit and miss!

John

Originally Posted by JDNSW

My guess would be either a CV joint or a wheel bearing. Neither are likely on a County, unless the item in question is dry or lubricated with mud instead of oil.

But diagnosing noises without hearing them is likely to be a bit hit and miss!

John

Thats 2 posts for wheel bearings, so I'll check them as well tonight.

Is the best way to check them to remove the drive flange, then:
- eyeball for general condition
- rotate to check for roughness
- try to rock top/bottom of the wheel to check for play?
Or is disassembly of the hubs/bearings the only real way?

Steve