Rumbling/bubbling noise is rear of R129?

[Sdemon]

Hi there.

I have recently acquired a 500sl from the 1993 period.

I have noticed that on startup, there is a strange rumbling/bubbling noise that comes from the rear. Perhaps the drivers side rear to be more exact. It’s short lived and then disappears.

Does anyone know what this might be?

Many thanks in advance.

 

[Wearsafoxhat]

Hi,

Could be the fuel pump priming itself


Sent from my iPad using Tapatalk

 

[Sdemon]

Thanks for the reply. Would you say it’s a normal sound or one that means that the pump is on the way out?

Thanks

 

[Wearsafoxhat]

I think is is normal as is the higher rpm on start up for a minute.
I’m not sure mine “bubbles” but can hear it run , prime.

Does yours have ADS suspension ? It could be that, though do not have it myself so only a guess.


Sent from my iPad using Tapatalk

 

[LostKiwi]

My fuel pump whines for a few seconds when ignition is turned on.
Pump is located just to the right of center line of the car just in front of the rear wheel.
There's a plastic cover over the pump. It could be the pump rattling on that if it's mounts are shot.

 

[Sdemon]

No ads suspension.

I do know the pump has been replaced In the past. I think it need a re look then.
Thanks

 

[davidsl500]

Get someone to turn the ignition on whilst you've got your ear to the drivers side rear arch. The pump (s) should give a nice clean whine for a few seconds or so and then all should be quiet. I say pumps because you may find 2 in line followed by the fuel filter. I had to change both of mine when I left the engine idling and the tank ran dry dragging many years of debris through them. The fuel filter is the last in the chain so no help!

 

[Sdemon]

It’s definitely not a whine. Only happens on start up, sounds like the sound of bubbling under water and then stops. A deep muted tone however.

I’ll have to get it checked out.

Thanks again

 

[Sdemon]

Still have no idea what this noise is
Happened again this morning on start up but It could not be reproduced at the mechanics.

I had the fuel pumps examined and they said it was secure.

any other suggestions?

 

[Oldspanners]

Do you have any seats with massaging or pneumatic functions?
Friend searched for ages for a noise before he found out it was a pump for the seat.

 

[Sdemon]

No features like that for the rear seats.

The only other pump I can think of is the hydro-pump for the roof mechanism that sits in the boot where the spare wheel lives.

any one experienced this noise with that pump?

 

[ajlsl600]

Get someone to turn the ignition on whilst you've got your ear to the drivers side rear arch. The pump (s) should give a nice clean whine for a few seconds or so and then all should be quiet. I say pumps because you may find 2 in line followed by the fuel filter. I had to change both of mine when I left the engine idling and the tank ran dry dragging many years of debris through them. The fuel filter is the last in the chain so no help!

Another bit of great design.!!!

 

[Oldspanners]

No features like that for the rear seats.

The only other pump I can think of is the hydro-pump for the roof mechanism that sits in the boot where the spare wheel lives.

any one experienced this noise with that pump?

As far as I remember the pump is situated somewhere behind the front seat.

 

[LostKiwi]

As far as I remember the pump is situated somewhere behind the front seat.

Roof pump is in the boot under the spare wheel.
Roof hydraulic control solenoids are located on rear side bulkheads next to rear seats.
Fuel pump is located under the car behind the drivers seat (near rear subframe) next to fuel filter.
PSE pump is located drivers side below fuel filler above front end of battery.
Can't think of any other pumps or solenoids in the rear.

 

[Oldspanners]

Roof pump is in the boot under the spare wheel.
Roof hydraulic control solenoids are located on rear side bulkheads next to rear seats.
Fuel pump is located under the car behind the drivers seat (near rear subframe) next to fuel filter.
PSE pump is located drivers side below fuel filler above front end of battery.
Can't think of any other pumps or solenoids in the rear.

This is what I remember but exactly where? https://mercedes.7zap.com/en/eu/fg/car/sl-klasse/sl+500/44f/129068/fg/0/0/80/0/135/0/0/

 

[LostKiwi]

This is what I remember but exactly where? https://mercedes.7zap.com/en/eu/fg/car/sl-klasse/sl+500/44f/129068/fg/0/0/80/0/135/0/0/

Looks like PSE pump to me. Right side of car, under fuel filler.