Hi All

I noticed today that when I turn the engine off and listen under the bonnet of my 1994 Favorit I can hear a hissing noise.  I thought initially it was coolant hose but seems to be coming from the brake servo area. Not sure if it hisses with engine on as can't hear over sound of the engine .

Brakes in general feel ok but i did notice today that with the car idling if I press and hold the pedal, as I release it the car momentarily stutters.

 

Will check the vacuum lines tomorrow once there is some daylight but is there any other way to check if the servo is gone?  Also does anyone know if the Felica servo fits the Fav?  2 weeks now until my European road trip and I guess sourcing a Fav servo might not be that easy in short timeframe

 

Cheers

Wes

First you have to be 100% sure what is the source of the hissing noise. In the absence of a stethoscope for mechanics you can improvise using a funnel and 1 meter of rubber hose to pinpoint the source of the noise. Stick the tip of the funnel into the hose. Put the opening of the funnel to your ear. Slowly sweep the suspect area with the end of the hose until you hear the noise louder.

 

The test for the brake servo is generic.

1. With engine off, pump the brake pedal a few times till it hardens

2. Keeping the brake pedal pushed start the engine.

3. The brake pedal should start to sink.

 

The brake "stuttering" can be as simple as old brake fluid or air in the system, or you might need a repair kit for the brake pump.

 

For the compatibility of the parts for Favorit and Felicia, use the pinned topic Online catalog with PART NUMBERS and ILLUSTRATIONS

Edited 5 July, 20197 yr by RicardoM

15 minutes ago, RicardoM said:

First you have to be 100% sure what is the source of the hissing noise. In the absence of a stethoscope for mechanics you can improvise using a funnel and 1 meter of rubber hose to pinpoint the source of the noise. Stick the tip of the funnel into the hose. Put the opening of the funnel to your ear. Slowly sweep the suspect area with the end of the hose until you hear the noise louder.

 

The test for the brake servo is generic.

1. With engine off, pump the brake pedal a few times till it hardens

2. Keeping the brake pedal pushed start the engine.

3. The brake pedal should start to sink.

 

The brake "stuttering" can be as simple as old brake fluid or air in the system, or you might need a repair kit for the brake pump.

 

For the compatibility of the parts for Favorit and Felicia, use the pinned topic Online catalog with PART NUMBERS and ILLUSTRATIONS

 

Thanks.  I tried the test for brake servo and it passed.   I will check the location of the noise again tonight but pretty sure its the servo .  This was also backed up by the fact that if I turn the engine off and pump the brake 4 or 5 times with engine off the noise is gone. 

 

I was tempted to just change the servo as I found and aftermarket one for reasonable money online but reading the Haynes manual it suggests that the input rods on the post 1992 Favorits are not adjustable and the servo needs to be a "matched pair" with the master cylinder. I am guessing this is not going to be possible with after market items so will keep fingers crossed that it is a leak in the hose and not the servo

 

 

Brake servos tend to rot at the bottom part from condensation/age. Typical Favorit disease...

18 minutes ago, RicardoM said:

Brake servos tend to rot at the bottom part from condensation/age. Typical Favorit disease...

 

Ah ok. Will have a good look around the bottom of the servo then. Looks quite old so would imagine its the original.

Does anyone have experience about fitting a new/aftermarket servo ? The Haynes manual says not only that the adjustment in the post 1992 input rod is gone, but the master cylinder diameter is different too.  There only seems to be one replacement servo I can find but not sure how to know if its compatible with the master cylinder

 

Edit

Just checked again and the aftermarket servo is only for pre 1993 cars..    

https://www.skoda-parts.com/spare-part/115595010-brake-booster-cn-26715.html

 

Looks like I could be in trouble if the servo has rotted out 😞

 

Edited 5 July, 20197 yr by wesacosa

I had a similar problem with hissing noise plus sometimes while i was in Stop sign the brake pedal was a little bit ''stuck'' on the floor.

In the begging i thought it was a ''lubricate me' problem or a brak-switch but not.

 

The responsible for this was a gauge which i had installed in the left column,was a cheap Vacoum 7 colour analogue.

After i removed the hose inside the engine bay (and remove it) everything went back to normal.

 

I asked my mechanoc but he said the worst scenario is the ''ageing'' and to buy a new servo-break is extremely rare to find it new.