Menu toggle

noisy pump

da_gleadless

da_gleadless

New member
Hi,

So I picked up my 964 and first of all... wow!!!

It drives amazingly and is everything i expected it to be!

The drive home was slightly nerve racking as I felt like i had a new babe in arms only with a 3.6 flat 6 to boot :)

Having got in the car for a second time after 20 mins rest i noticed a slight whurring noise that sounds like its coming from a pump?? which i located to be in the front passenger side having popped the bonnet!

could it be the fuel pump?

There no faults with the car and it drives what seems to be normally, but the pump does sound slightly noisy, is this normal?

its worth mentioning I didn't notice this on the 1.5 hour drive home!

I haven't got my Manual through the post yet, so does anyone have any ideas what this might be?

(sorry for the noobness)
 
Hi

I think you will find it is a brake pressure pump which runs for a while when you start the car. Not a very technical answer I know, but i think its pefectly normal as I asked the very same question a few weeks ago during a visit to a local porsche specialist. I'm sure someone will follow up with the exact in's and out's.................

enjoy your car

Simon
 
I hope that is the case, but it seemed to continue for the duration of my drive around... about 20 mins?

thanks for the reply
 
I've just been out for the last two hours [:D][:D][:D] and its stopped...very random!

I feel like a car hypercondriac lol
 
Chris,

As Simon says, it's the hydraulic pressure pump. The C4, in common with the RS and Turbo, uses an electric pump to create and maintain a very high hydraulic pressure in the pressure cylinder (often referred to as the "bomb"). This pressure cylinder provides the power assistance to the braking system - and the PDAS traction control system in the case of the C4.

It's essential to learn the idiosyncrasies of this system as it will enable you to avoid a number of otherwise mysterious alarms when you first drive off. When you turen the ignition on, before starting the car should SHOULD get 4 lights on the dash that stay on. They are the alternator charge, spoiler, ABS and PDAS lights. You would normally hear the pump running - assuming you don't start the engone - and just before the pump stops you should see the ABS and PDAS lights go out. That is the indication that the hydraulic pressure has reached it's cut-off level. It's useful to time how long it takes for the pump to stop. In a perfect world it should take something like 20 seconds or so but you may find it takes longer and it important to check. You MUST NOT let the pump run for more than 2 minutes as it indicates a pressure problem and will likely lead to the pump burning out.

The presure gets "used" as the braking (and PDAS) are used and the pump will come on at apparently random intervals to replenish the pressure. You normally won't hear it when driving as the music from the rear end will drown out the noise. If you press the brake pedal when parked (with ignition on) you should hear the pump start up after 4 or 5 pumps of the pedal.

If the pump runs for significantly more than 20 seconds after standing over night I'd recommend that you get the primary hydraulic system bled.

Incidentally, if you drive off too soon after switching on the ignition - i.e. before the hydraulic pressure has built up sufficiently - you will get an alarm on the dash with a gong sounder and the central "!" light. Many C4 owners will admit to seeing it and wondering why. A little patience when you first start the car is all that's required. The C4 is NOT the ideal get-away car!!!

Over time you'll get to know the car's little quirks - and love it more because of them!!! Enjoy!!

Regards

Dave
 
Hi Dave,

Firstly thanks for the advice. The car in question is a 964 C2, but i assume the hydraulic pump still has the same uses!

I was out in the car for a few hours yesterday along with a riduclously traffic engulfed 3 hour commute today (normally 50 mins) and the noise maintained it volume throughout both journeys!

I was thinking it was the fuel pump, but theres been no stutters or fuel problems!

The brakes have been fine through out both journeys also. With this being said, then I can only assume (from the advice given) the pressure within the system does not reach full capacity as there is too much air in the system and will require bleeding as you say.

This being said, I switched the ignition on and got 4 warning lights, but the noise only starts on ignition of the engine. There are no warning lights and no ! warnings. Do you still think it will be the hydrauilic system?

Again sorry for the noobness, but as soon as my manual arrives in the post I will be burning the midnight oil swatting up on my pride and joy, and how to fully understand her!



 
OK - things have got really confused now. I jumped to the same conclusion as Simon from your description of a pump in the front passenger side as being the hydraulic pump. To answer your question about the C2 - NO, the C2 doesn't have the same hydraulic pump as it uses a more standard vacuum servo system. As I mentioned in my previous reply, the pump is only used on the C4, RS and Turbo.

The fuel pump is underneath the car, not in the luggage compartment, so I'm at a bit of a loss to imagine what this pump is. I think you might have to locate it and take a picture of it so we know what you're talking about. I can't, for the life of me, think of anything other than the fuel pump that's going to run all the time.

Dave
 
Hmm Ok, I will get the tools out ASAP...

Im guessing like you said it is the fuel pump... do you think the noise is a prerequisite to failure?
 
You must log in or register to reply here.

Posts made and opinions expressed are those of the individual forum members

Use of the Forum is subject to the Terms and Conditions

Disclaimer

The opinions expressed on this site are not necessarily those of the Club, who shall have no liability in respect of them or the accuracy of the content. The Club assumes no responsibility for any effects arising from errors or omissions.

Porsche Club Great Britain gives no warranties, guarantees or assurances and makes no representations or recommendations regarding any goods or services advertised on this site. It is the responsibility of visitors to satisfy themselves that goods and/or services supplied by any advertiser are bona fide and in no instance can the Porsche Club Great Britain be held responsible.

When responding to advertisements please ensure that you satisfy yourself of any applicable call charges on numbers not prefixed by usual "landline" STD Codes. Information can be obtained from the operator or the white pages. Before giving out ANY information regarding cars, or any other items for sale, please satisfy yourself that any potential purchaser is bona fide.

Directors of the Board of Porsche Club GB, Club Office Staff, Register Secretaries and Regional Organisers are often requested by Club members to provide information on matters connected with their cars and other matters referred to in the Club Rules. Such information, advice and assistance provided by such persons is given in good faith and is based on the personal experience and knowledge of the individual concerned.

Neither Porsche Club GB, nor any of the aforementioned, shall be under any liability in respect of any such information, advice or assistance given to members. Members are advised to consult qualified specialists for information, advice and assistance on matters connected with their cars at all times.

Porsche
Lockton
Pirelli
Officially approved
Oracle Finance
WEX Esso
Collecting Cars
Archant Dialogue
Back
Top