Transmission noise

[danielsprague]

Hi

I'm 7 months / 34,000kms into my trip across Asia in a 1993 Toyota Hilux Pickup - 2.4D 4x4.

There's a backround noise when driving, which seems to come from the engine / front bulkhead. It's particularly noticeable through the clutch pedal, and is most apparent when revving the engine with the clutch down, or changing gear. The noise is then a light tapping, spinning-down noise. It sounds too light and external to be big end / main bearing noise. I would blame the clutch release bearing, or input bearing in the box, but wouldn't these be still when the engine is revved with the cluch pedal down? My suspect is a bearing in the PAS pump or alternator. The timing belt has done about 55,000 KM/S (not miles), and looks like new.

Theres a separate (I think) vibration, which is very apparent as you go into 4th at 45km/h through to about 50-55, then goes above this. It is worse when accelerating / going up hills. (This is in 2WD, I very rareley use 4WD). I have replaced the centre bearing, and had the UJs checked - there is a tiny amount of movement in them, but everyone says this is fine.

So I'm a bit stumped about this. It has been getting gradually worse over the last 20,000kms.

Any suggestions would be welcomed

Thanks

Daniel

[silver G]

Hi Daniel, just some quick thoughts:-
check the props again and grease the uj's and the sliders if you have them, I'm not sure there should be any play. Stick everything in neutral and see if there is more play than last time.
check engine and gearbox mountings
sorry, can't be more help.
Good luck
Chris

[Dessertstrom]

Hi Daniel,
Your thrust bearing is turning when you press the clutch in, that is why it's a bearing or in some cases a carbon type pad. I can't remember if your Toyota is a cable operated clutch or hydraulic, if it is cable then you need to adjust it to put some free play in it, about 1/8 th inch at the clutch fork. The thrust bearing would then clear the pressure plate in the off position and if it is the bearing that is causing the noise it will stop until you press the clutch. Some hydraulic systems also have an adjuster at the slave cylinder end.
I trust you have checked the oil in the gearbox.
Have you used the listening stick method to trace a noise ?
A long screwdriver or long socket extension touched to a unit and the other end at your ear while the engine is running.
BE MOST CAREFUL IF YOU USE THIS METHOD OF DETECTION AND MAKE SURE YOU HAVE SOMEONE WITH YOU.
After saying that I have used this method many times without misshap.

Cheers
Ian

[mattsavage]

Hi. The vibration sounds like it could be a propshaft. It could simply be a weight that has come off the prop (they are tiny weights) or maybe a damaged or worn UJ. The other (main) problem sounds like the clutch release bearing. This is spinning with the clutch cover (that is bolted to the flywheel). Try sitting with the engine running and depress the clutch pedal and rev the engine on and off, up and down etc. If there is a problem with the release bearing you should be able to hear/feel it (maybe!).
It could also possibly be the input shaft bearing in the gearbox (like you say), I think this will make a humming sound under load or over run.
As a matter of course check the oil level in both gearboxes anyway.
Oh, and check the rear prop centre bearing again if you can.
To check the bearings in the PAS and alternator, place a big screwdriver (or similar thing) between your ear and the bearing area, press the flat screwdriver end on the casing near the bearing, then press your ear to the screw driver handle with the engine running. Be careful though, watch out for spinning fans, belts etc!! You can hear the noise of the bearings, they sound very noisy anyway, but if there is a worn one it sounds even more noisy! It's hard to explain, but play about with different sounds on the engine and you should be able to get a feel for what is normal. Or if you have a stethoscope, that's even better. You can actually buy proper stethoscopes for doing this very thing.

Right, that's a lot of writing for me, I'm off for a hot chocolate and a sit down...

Cheers,
Matt

[gilghana1]

I had a similar rattlly noise (well actually dozens) in the Defender - turned out to be the alternator. Fixed that and then the belt tensioner started... Sorry not much help!

I am off for a glass or two of Nederberg with our staff before we close down and I pack up the troopy to head for Mali tomorrow a.m.

[silver G]

Originally Posted by gilghana1

I had a similar rattlly noise (well actually dozens) in the Defender - turned out to be the alternator. Fixed that and then the belt tensioner started... Sorry not much help!

I am off for a glass or two of Nederberg with our staff before we close down and I pack up the troopy to head for Mali tomorrow a.m.

Lucky bugger enjoy

stuck here in the cold with sausage butty

[gilghana1]

Many thanks Chris!
got delayed a couple of days... :-( but now packed and checkinh fellow Hubbers for the last time for a while.

Hope everyone 'here' has a great Christmas and New Year
Gil
(curently enjoying a nice glass of water due to too much festive cheer last night)

[silver G]

Cheers Gil, looking forward to pictures

[danielsprague]

A little bit more info.

I am not sure whether there are two problems, or if all the noises come from the clutch release bearing.

what sounds like a transmission noise is definitely strongest as the car picks up in 4th, but i can hear it now as the car picks up in any gear. perhaps there is some combination of engine speed and torque which makes it most noticeable in 4th... this implies the noise is related to engine speed, rather than road speed, so i do not suspect the propshaft. i had the whole thing off, a new centre bearing pressed on, and the ujs checked and greased. I don't think it's lost any weights, and the noises have been getting progressively worse, no sudden changes. at higher speeds in first, there is a judder in the delivery.

the gearbox oil is at the correct level, the correct grade, and has done maybe 10,000km.

my suspect is definitely the thrust (clutch release) bearing, though the bearing was brand new when i left. I ut a new clutch in 35,000km ago, but the car sat unused for a year, so perhaps some damp got into the bearing. the bearing is a closed type taper roller bearing which i didn't think needed greasing before use?

I don't really think it can be the input bearing, as this would definitely be still with the clutch down (for longer than it could take to spindown) and the vehicle stopped. i do have a spare though 9unlike the cluctch release bearing), so aside from the work involved in opening the box, it wouldn't be a disaster.

trouble is right now i'm in Iran, where there are no diesel cars, so no diesel specific spares, and i'm pretty sure the clutch / gearbox are different diesel vs petrol. i dare say it will hold out until pakistan, if not... well there's always DHhell.

thanks for your help guys, any more wisdom would of course be appreciated.

Daniel

[Dessertstrom]

Daniel,
You can eliminate the thrust bearing by disconnecting the cable/pushrod at the clutch fork and pushing the fork back to give the bearing clearance, when it is clear of the pressure plate it will not turn and so will not make a noise.
One possibility is the centre bearing in the end of the crankshaft that the end of the clutch shaft fits into. If this bearing has got so rough it can make the clutch shaft turn when the clutch is depressed. Can't think of an easy way to check this one though.
Sealed bearings shouldn't need greasing they are supposed to be greased during manufacture and standing for a year would not be a problem. I have just checked the thrust bearing on a gearbox that has been sat outside my villa for three years under cover in salty sea air and it is still smooth.
Cheers
Ian

[danielsprague]

Hi Ian

Is the bearing you're talking about in the end of the crankshaft called the spigot bearing? It would be good if that was the culprit, as I have a spare...

Daniel

[Dessertstrom]

Yep,
Spigot bearing, first motion shaft bearing, clutch shaft bearing and clutch shaft centre bearing and probably more. It's about an inch or so in diameter the shaft having a small diameter end after the splines about an inch long that fits in the centre.
The only way to check this bearing is to remove the gearbox. This is the bearing that you have to align the clutch with so that the clutch shaft slides straight in.
Cheers
Ian

[Dessertstrom]

Daniel,
These bearings can be a Brd to remove. You need a small puller like a slide hammer, this fits inside the small hole and expands to grip the bearing track.
Without a puller you can hydraulic it out by packing grease in through the bearing hole and use a drift the exact size diameter of the end of the clutch shaft. Put the drift in the hole and hit it with a good size hammer. This method is messy and requires plenty of room to swing the hammer.
This method will not work if the bearing has started to break up as the grease will just come through the seals.
If the centre track has broken away from the outer track you have got problems as these tracks are hardened steel and difficult to drill.
DO NOT attempt to burn the track out as this will heat up the end of the crank and can damage the crankshaft oil seal.
In the past I have had to use a big chissle to crack the bearing track and then lever it out.
You really do need a puller as these other methods are a real pain and I had the use of a ramp in a vehicle workshop.
If you are not a mechanic then you need someone to do the job for you, with a slide hammer/puller it is a piece of p**s.
Cheers
Ian

[danielsprague]

OK, a quick re-cap on the situation.

I have two or three noises.

1) a tapping, spinning-down noise (not big end noise), when the engine is revved with the clutch pedal down (in any gear) and whjen shifting up through the lower gears whilst driving.

2) a vibration which makes the mirrors vibrate which is strongest as 4th gear is engaged (much less noticable at the same speed in 3rd), but which I think is also present in other gears

3) a whirring, meshing noise with the box in neautral, clutch pedal up. If I put the transfer case in neutral, and engage the gears, the whirring is greatest in 4th, though noticable in all gears.

I now have the gearbox out of the car. THe clutch release bearing was worn, it turns smoothly but the inner race is loose (rattles when shaken) inside the outer race. Seems to have got wet and lost lubrication. The flywheel also has a couple of hot-spots, and will be machined again. Looks like the clutch may have been slipping a little, though I think this was only ever at higher engine speeds in 1st gear. The spigot-shaft bearing is fine.

I've hand cranked the gearbox in all gears, and it is silent, and feels smooth apart from some the faint feeling of gears meshing, which the mechanics said was normal (I don't trust these mechanics though). There is also some lateral (i.e. side to side, not axial, front to back) movement, which the mechanics also tell me is normal.

1) I blame the clutch release bearing for noise (1), with the inner race rattling as the rotation of the flywheel / clutch pressure plate slows when the throttle is released.

2) Would a worn bearing or gear in the gearbox make the car shake as per noise (2)? 4th gear is (I think) straight-through (i.e. input and output shafts turn at same rate), which may lend the more movement, amplifying a vibration from another source. I think the engine mounts may be worn out - they will be replaced regardless.

3)Could the clutch release bearing be responsible for this whirring sound? Surely with the clutch up (when the noise occurs), the race which contacts the pressure plate (when the pedal is pressed) would be stationary within the outer race, which moves with the input shaft.

My dilemma is whether to open the gearbox. It feels OK, but it would be very annoying to put it back in and find that the noise is still there. The mechanics here in Pakistan don't have gear pullers (despite being an authorised, genuine Toyota Service Centre), but I think I can take the gearbox apart and inspect the bearings without needing a puller. Only problem is I don't have a new seal, though I have silicone RTV sealant.

Daniel

[Martynbiker]

Daniel My money is on 1st Thrust Bearing
2nd Spigot bearing.

Dessertstrom is right they are a PIG to get out without a puller!

If the engine is ticking over and in Neutral, and you depress the clutch and the noise GOES AWAY or gets Quieter its DEFINATELY the Thrust bearing.

Hope this helps

Martyn