SBC pump or gearbox problem

[Indrit]

Hi.
I hear some buzzing during run, like SBC pump. Buzzing is not periodical is not related with accelerator pedal level, not even with running speed of the car but buzzing is present during run (not continuously).
My question is: do normally SBC pump works while the car is running in certain speed even if the break pedal is not pressed for last (lets say) 5min?
-May it be gearbox problem?

 

[Deleted member 37751]

Simply sounds like it is the SBC pump just doing it's thing, which is exactly how you describe it.

 

[Alps]

SBC - its a pump that pressurises the brake system so it will run after so many pedal presses. yes it will run randomly

 

[Indrit]

Just to bee sure, does buzzing (if it is not SBC pump) indicate the start of any problem of the gearbox?

Thank you guys for help!

 

[Alps]

indrit, it sounds like SBC pump, if you think its gearbox take it to an indi straight away!

 

[Deleted member 37751]

Just to bee sure, does buzzing (if it is not SBC pump) indicate the start of any problem of the gearbox?

Thank you guys for help!

I've never heard of a gearbox 'buzzing', I've heard of grinding, thudding etc. The gearbox makes a more mechanical sound than an electrical one.

 

[John]

When you hear the buzzing, rest your foot on the brake pedal.

If you can feel it vibrate, it will be SBC.

 

[Indrit]

No I cant feel it when I press break pedal. It disappear immediately when I remove the foot from accelerator pedal.
What might it be?

 

[BlackC55]

It could be a torque converter vibration.

 

[Indrit]

Is it normal to vibrate torque conversion?

I monitored the problem carefully and buzzing (light bzzz...) seems to appear when clutch is joined with disk for x gear or from neutral to x gear and vise-versa (sorry I do not know how this works on auto transmissions), so when motor power is sent to wheels and when this interrupts.
Sorry for this non professional explanation.

Thank you for helping me to find something strange.

 

[John]

In an auto, the torque converter replaces the mechanical clutch you are referring to in a manual car. (Not to confuse but you still have clutches but not in the same sense as those which most people refer to).

It sounds like you are saying that vibration occurs when you are engaging drive or neutral (switching the lever to D from N and vice versa) and then when changing gears as well?

But, regardless, it does not stay vibrating all the time, just during this?

 

[Indrit]

Sorry I forgot to add even this: that buzzing (light bzzz.. for about 3sec or when I hear bzzz... and do not change accelerator level it continues) is not filled when gears are changed from one to another, it spears only when passing from x gear to neutral or from neutral to x gear (automatically not manually, made by transmission)

Thanks again!

 

[John]

To be honest, now we've probably identified it not being SBC, it sounds like something more serious.

You are probably going to need to take it to either a specialist or MB to check it out.

 

[Indrit]

Thank you guys for reply.
It vibrate (very light one, it does not hears, it may fill only if you have the leg on accelerator pedal) only in the moment from neutral to x gear.
During run when I push-off the accelerator pedal I think the transmission goes to neutral position, push the accelerator pedal back it catch x gear (x=depends from the speed that the car is moving in that moment), in this moment I hear that little vibrating for a while. It does not occurred during normal gear change (with accelerator pedal normally pressed)

Today I will check the car with any computer software for any error and will write back here.

 

[Alex Crow]

This is sounding more and more like torque convertor juddering.

Typically it will happen with light acceleration up an incline at around 45 mph.
Throttle position is critical, with either an increae or decrease in throttle making it dissapear.

As it worsens it will occur in a greater range of speeds and conditions.

The juddering is typically like driving over the corrugated white lines at the edge of motorways etc, very distinct and sudden.

Other symptoms linked to TC problems are surging like slowly increasing/decreasing thottle.

Very often just a change of radiator and thorough flush of transmission fluid are all that is required.

 

[BlackC55]

+1.

I have had recently a few TC's breaking up inside causing the same symptoms. The bad thing is that when this happens it fills the box up with very fine swarf and causes the gearbox to need a re-build too.

 

[Indrit]

Thank you guys for help!
I checked it with software (computer) and no faults was present.
-Does this helps?
-Pls, what consist a re-building of transmission.
-Do I must change radiator too?

thanks again!

 

[Alps]

Indrit, surely instead of thinking the worst case and stressing over it, visit a indi and get it checked, that way at least your questions are not speculative and you can ask the correct Q`s .

 

[flt.eng]

Thank you guys for help!
I checked it with software (computer) and no faults was present.
-Does this helps?
-Pls, what consist a re-building of transmission.
-Do I must change radiator too?

thanks again!

Sounds as though this could have been started by the devil :VALEO: (radiator) Check this out, you have the right year car, for this to be the cause.

 

[Alex Crow]

+1.

I have had recently a few TC's breaking up inside causing the same symptoms. The bad thing is that when this happens it fills the box up with very fine swarf and causes the gearbox to need a re-build too.

Indeedy, these are so hard to quote.

Had a w203 kompressor in 2 weeks ago with the usual symptoms (complete with gearbox oil in water, Valeo rad and the right year/model for the problem according to WIS).

Had to give 4x estimates...

1. New rad, flush fluid and replace with filter + gasket.
2. As above plus replacement or repair of TC (MB now do a reconditioned TC).
3. As above plus valve body refurb.
4. As above plus gearbox rebuild.

Poor chap was really worried, I hoped for the best.
Luckily the rad and fluid flush/change did the trick, customer happy.