Volkswagen 1.9 TDI - Booming / roaring while driving in 4th and 5th gear

Hi!
I am asking you for advice, which may be the reason for the buzzing / roaring while driving a Volkswagen 1.9 tdi 90 HP (manual transmission, without a dual-mass wheel) in 4th and 5th gear.
Noise only occurs when driving at a constant speed between 70 and 100 km / h, as soon as I lightly press the acceleration (maintaining the speed).
I would add that sometimes the noise is high and you can feel the slight vibration of the car - as if something was rubbing. However, if it was friction, it would probably occur all the time?

The thing is, pressing the clutch makes the roaring stop. When idle, it also stops. Similarly during acceleration and engine braking.

Unfortunately, the cause could not be found at the diagnostic station ... That's why I am asking you for ideas, what I could check.

It's hard to say - it is not known what model, because vw 1.9tdi produce over 20 years.

Dude, no offense, but what technique do you drive this car. Just for the record, it is a tdi engine, so it must have and the right speed. Driving at a speed of 70 km / h in 5th gear is rather a "homicide" for this engine. This engine starts working properly from min. 2000 revolutions per minute.
I drove a Passat with such an engine before. In my opinion - the sound effects described by you can be caused by driving at low engine revs.

It is quite possible that the author uses PSJ, although at 70km / h in 4th gear it should be around 2000rpm. Well, unless the clutch is fed up then it happens differently.

The bearing supporting the clutch shaft sits securely and does not center the clutch disc. All you need is a slight shift after clutching the i9, the engine will vibrate.

Let me explain.
The car has a 1Z engine from 1995.
The fourth gear is 70-90 km / h, the fifth is over 90 km / h.
The sound is unlikely to sound like a stewed engine at low speed. Rather, it's friction - like bearings ..?

Indeed, I do not always drive at a constant speed above 2000 rpm, but I never choke the engine at low speed and try not to drive below 1700. I don't have a tachometer, but I once rode with a connected interface to check how the car behaves at different speeds.
I would add that for a year everything was fine and the specific noise has been accompanying driving for some time. I haven't changed my driving style.

I'm going to check the oil in the chest, but only after I deal with the cork. Although it seems to me that a damaged box should make noise all the time, and not only when gently pressing the accelerator pedal in the strict speed range ...

Joints replaced.
I changed the wheels, but if something rubbed, it should probably be heard all the time.

Only yesterday I was able to take care of the car. I changed the oil in the gearbox - the level was slightly below the minimum and now the gears are going quite well. Unfortunately, the humming I described still occurs.
Does a damaged clutch shaft bearing bear such symptoms? Shouldn't it make noise all the time?

Accelerate the car to 100km / h, loose it - press the clutch - release - any changes? Re-apply with gears 4 and 5.
If you rode with no oil - below the mine, maybe the crate has fallen.

Hello.
I would check the alignment of the front and rear wheels. It is an old car so something could have gently broken apart. As you wrote, the buzzing occurs above 70km / h so this could be it.
It would be worth checking again:
wheel bearings
gearbox condition (oil quantity, mode status)
tires are not serrated
the clutch release bearing - it may not have slack, but it will be dry inside and it will also humming

Hi
Today I will test the car on the road by the method kakibara and I will let you know.

I will definitely check the wheel alignment, although the humming occurs not always, but only when gently pressing the accelerator pedal (when I maintain a constant speed). When slowing down and accelerating (whether on the run or at ease) everything is fine.
Wheel bearings are normal. The tires have one season and only 2-3 thousand km of mileage.
The thrust bearing actually has no clearance, but I don't know if it is lubricated properly; to check it you need to dismantle the clutch?

The oil level in the gearbox is now normal. How does it look inside - I have no idea ...

moop wrote:

The thrust bearing actually has no clearance, but I don't know if it is lubricated properly; to check it you need to dismantle the clutch?

The thrust bearing usually does not have any lubrication from the engine, etc. it is simply factory lubricated with the appropriate grease and when it dries, it loses its lubricating properties and, as a result, the bearing starts to roar, squeak or simply fall apart. We do not grease bearings and replace them.

moop wrote:

The oil level in the gearbox is now normal. How does it look inside - I have no idea ...

Now normal and before? What was it riding on? When was the oil changed in it? It would be best to swap it for another crate and check it but it involves expense.
Do all rims have the same width and offset? Are they all equal?

I moved forward slightly to solve the problem.
I tested the car on the route yesterday, but earlier I changed two front wheels to another one - borrowed; admittedly aluminum and wider (protruding beyond the outline of the car) and with winter tires, but with the same diameter.
Interestingly - in 4th gear the humming sound completely stopped; I checked in the 70-110 km / h range.
In the 5th gear, it hums much quieter and only after exceeding about 110-120 km / h. Below - silence.

Therefore, I eliminate - probably rightly - problems with the gearbox and clutch.
Was it a matter of convergence?
The steel wheels and tires on which the buzzing occurs are new and balanced. They only have a smaller ET, but they don't seem to rub anything.

moop wrote:

Was it a matter of convergence?

I wrote to you before that you could check it. Did you check?

Of course, I'm going to check this coincidence.
I started with the simplest (no-cost) things.

I will definitely inform you about the results of the study.

At home in the car I replaced all the bearings in the wheel hubs. First, he began to howl at the back so that it seemed the least to me. After the exchange came the front. I exchanged both together. And finally there is peace. I tasted a bit but it was worth it.

It's just that the bearings make noise all the time. For me, roaring occurs only in strictly defined situations ... For now I will focus on convergence.

It's not all the time. They were starting to make noise from around 40 km / h.

Hello after a break.
Convergence checked - it's okay.
Bearings - also fine.
Tires changed to different and the wheels balanced again - roaring unchanged.

Evidently something is wrong with the rims ...
The assumed 15 "steel wheels have an offset (ET) of 42 and a width of 6.0".
As they are mounted directly on the hub, they gently rub against the brake calipers, 5mm thick aluminum spacers are added.
I think to try to put other steel rims - no distances.
Will ET 36 and width 5.50 "be OK? Will there not be any changes in terms of distance from the clamp?

If I do not choose other rims, I will still have to try other distances (although these are even and undamaged) and if it does not help, then I must accept the noise during the ride.

ET detachment determines the horizontal distance between the rim assembly plane to the hub and the plane of symmetry. So to put it simply, the larger the ET, the deeper the wheel hides in the wheel arch. And the smaller the ET, the more it protrudes from the wheel arch. So in your case less weaning will be better.
As for distances, centering measures and similar miracles, when working on vulcanization sometimes it happened that through these distances the rim unevenly settled on the hub which caused a roaring or vibration on the steering wheel. Personally, in my opinion it would be better to mount original rims without any distances.
Show the tread of the tires you have fitted.

As for ET, I understand that with the same width and smaller ET, the wheel rim will enter the wheel arch less and it will slide out more, but I doubt the 0.5 "smaller (5.5" instead of 6 ") and smaller ET ( 36 instead of 42) - I'm just afraid that the distance from the caliper will not change.
The problem is that other 15 "rims are difficult to access, and the original ones are 13" and I would have to replace a set of new tires with new rims (several thousand km) - and that means a lot of costs ...

The original are:
Diameter: 13 "
Width: 5,50J "
Embedding ET: 38.00

I have these:
Diameter: 15 "
Width: 6,00J "
Embedding ET: 42.00

And I have available such (then I replace the rims only - front without distances):
Diameter: 15 "
Width: 5,50J "
Settling ET: 36.00

Maybe it is a problem of these distances - it is very difficult to say.
Maybe I'll just try to replace them, maybe they have some invisible flaw. This is definitely a lower cost than replacing a set of wheels.

The tire tread does not bear any signs of wear - I have driven a possible 2 thousand km on them.