Chattering noise - speed / load related

[Bob]

Hey guys.
getting an increasingly present chattering noise from underneath. Seems mostly there when cold, but I can't be sure as I usually have the radio on. It seems to go away when the truck is under load at low revs, eg. Putting the power on in a higher gear at lower speed, and seems louder than the transmission is under less pressure, say doing 40 mph down hill, foot off the power. Dipping the clutch seems to have no effect.

I'm worried it may be something like an output shaft bearing but I don't know much about gearbox stuff. Any input would be greatly appreciated!

Bob

 

[StarCruiser]

Could possibly be the exhaust. Either loose at a joint or knocking against something. Worth a crawl under and just have a look around and see if anything is loose or if any bushes are worn or perished.

Bushes would probably be more of a bonking noise, the chattering you describe could also be a UJ. Grasp the prop shafts with the gearbox in N and see if they move at all relative to their flanges either end. There should be no movement rotationally and only the merest laterally if at all.

All depends on the sound really. I would have thought a bearing would be a whine.

Richard

 

[Shayne]

Exhaust is always the prime suspect , whatever noise you can imagine from whatever part you fear failing the most the exhaust has an uncanny ability to replicate that noise . When the noise is only under load its a bugger to detect where its coming from but your hearing it over the racket of the engine so if you jack it up and spin the wheels by hand you might still hear it .

 

[Bob]

My thoughts exactly on a bearing noise being a drone or whine. This is almost like a cross between a slipping belt and the click of the 'wheel of fortune'. It has no apparent effect on the way the truck drives. It doesn't happen on idle, as you say a bugger to replicate.

I'll have a good poke about tomorrow evening as I've to replace a flexi brake hose anyway. Just hoping it's not something that requires dropping the gearbox, that gets expensive, as I don't have the facilities for that job!!

 

[StarCruiser]

Slow or fast, at say 30?

Examples- Stone in tyre or playing card in bicycle spokes- or somewhere in between?

 

[Bob]

Closer to the playing card in the spokes. It does sound rotation related, but could be vibration/resonance I suppose. Not a click, but a 'tseek' Sounds like an industrial fridge motor that needs a bit of lubricating if you get me. (I say that because the cheese fridge in Lidl was making the same noise this evening)

 

[Shayne]

UJ i have crap hearing so i felt the vibes rather than heard it .

 

[StarCruiser]

UJ, drive near a wall with less noise around and just creep it slowly at idle. Bet you get a creak, groan,creak,groan,creak,groan as the UJ rotates.

 

[StarCruiser]

UJ i have crap hearing so i felt the vibes rather than heard it .

The state your UJ was in I felt the vibes before you arrived Shayne…[emoji3][emoji3][emoji3]

 

[Shayne]

Yeah but your a 3 hour drive from my house Rich and i knew something was amiss as soon as i got on the motorway 10 minutes after i set off .

 

[Bob]

Here's hoping.... A UJ would be grand. I even have a brand new one in the spares department of my workshop. (The end bit of the shelf in the attic) Investigations continue tomorrow. Meanwhile I have to pack for an India trip on Saturday, so whatever it is, it's likely to be dumped into the mechanics on Friday for the week. €€€

 

[StarCruiser]

It drive alright Shayne but it soon showed when you eased off. I think it had totally bypassed the squeaky squeaky stage and gone for full on rumble.

You obviously got back ok. [emoji4]
Typical Cruiser, refused to give in without a fight…[emoji6]

 

[Shayne]

It was my first Bob and once i stopped messing about and used a grinder to cut through the old one it was a doddle , if i had to do it again it would be a half hour job .

Rich if iirc i got into a bit of a race with a rangerover on the way home but 6 hours at motorway speeds with a buggered uj has to earn her a tough cookie badge

 

[Bob]

I'd have no problem changing it Shayne, did the rearmost one last year, but don't have time on my side this week. That's presuming it is a UJ!

 

[StarCruiser]

+1 on that Shayne.

I too had to use the disc cutter in the end. Went through easily if a little tricky under the truck.

 

[Sag]

Another thing might be worth a look at is the starter motor bolts,I've had one come off well that was after the garage fitted me a new starter and that gave a chattering noise.

 

[Bob]

Well, I've had a good prod around, and there's a tiny bit of play in the UJ's on the front prop..I can't see how that would cause the noise, but perhaps it is. However when rotating the raised wheel, I did hear a slight noise from what sounded like within the transfer box. After spraying exhaust joints and checking bash plates for stowaways, the noise is still there on driving. I fear it may be to do with the chain drive inside the box... But I can't say if the two sounds are related for sure, as the noise when driving is high pitched, and not a rumble.

I did at least get the brake hose changed so it'll pass it's test this week at least.

 

[clivehorridge]

Well, I've had a good prod around, and there's a tiny bit of play in the UJ's on the front prop..I can't see how that would cause the noise, but perhaps it is. However when rotating the raised wheel, I did hear a slight noise from what sounded like within the transfer box. After spraying exhaust joints and checking bash plates for stowaways, the noise is still there on driving. I fear it may be to do with the chain drive inside the box... But I can't say if the two sounds are related for sure, as the noise when driving is high pitched, and not a rumble.

I did at least get the brake hose changed so it'll pass it's test this week at least.

Id still re-pack the UJs or get them changed. I don't like the thought of any feelable play in UJs and especially if they may be dry.

When greasing, make sure fresh grease comes from all 4 caps. If they're sealed ungreasable units, my advice would be to change them.

 

[Bob]

Yeah I'm going to replace the UJ's for sure, just have to get a second one. I believe the two on the front shaft are the same. I'm just not convinced this noise would be caused by the UJ's, but I'll pack 'em with grease tomorrow and see does it make a difference. Will probably do the transfer box oil too.

Pain in the arse!

 

[clivehorridge]

The "chattering" sound and the change when under load are the only ways I could describe my front prop T/B end UJ, moments (maybe 20kms) before it let go. That's why I'm so insistent.

Id guessed it may be a UJ, but even after greasing it still let go. There was no discernible play in it either, I think it was so dry it had bound up before I greased it.

UJs are much neglected particularly by previous owners, and relatively cheap to replace. If nothing else, it will narrow down the checklist, if the noise persists.