Strange noise after starting.

rmcdonnell · 06-05-2008, 04:22 AM

Hi folks,

I have a 1989 2.7 944, that make a strange new noise after starting, and moving off.
I have never had it do it in reverse, which is how I get out of my drive.

Within a couple of seconds of moving off forwards, a strange, guite loud brrrrrrrrzzzzzzzzzzzzzztt
noise taking two seconds occurs, but does not repeat. Sounds like it's coming from the drivers side wheel arch (I'm European and so is the car, so this is the right side..!)

ABS? Steering Pump? any other thoughts?
It didn't happen, and now it does.

Weird.
Cheers
Russell

phoenix_iii · 06-05-2008, 04:44 AM

More info for those who can help.

Is it only cold starts?
Is it once a day?
Is it every start (from a stop)?
Is it easy to reproduce if you stop, turn car off, then back on, and take off?
What if you leave it in neutral and just push it forward?

Details!

rmcdonnell · 06-05-2008, 06:06 AM

Cold starts, or warm starts, in fact every start, but only after I move off.
Don't know if it will happen after an immediate restart, (I'll have to test) but I think it does.
Leave on in neutral and push: I will try this, next chance I get.

The noise is electrically started, I'm fairly sure, as if a switch is operated for a few seconds then stopped. Thanks for the ideas.

cheers
Russell

bazar01 · bazar01's Garage

Most likely the ABS pump. It does the same thing on my previous S2 after start up and moving off.
The ABS pump finally went out after one year and had to disable the ABS system to turn OFF the "!" and ABS light.

Tishabet · 06-05-2008, 07:02 AM

Quote:

Originally Posted by bazar01

Most likely the ABS pump. It does the same thing on my previous S2 after start up and moving off.
The ABS pump finally went out after one year and had to disable the ABS system to turn OFF the "!" and ABS light.

I agree, probrbaly your ABS pump.

Bazar01: what "went" on your ABS and how did you disable the system?

Slam · 06-05-2008, 10:47 AM

Fuel pump? Although it may whine more than the sound you describe.

rmcdonnell · 06-05-2008, 01:11 PM

Hi,

Tried a further test: on a straight bit of road, doing 40 mph, turned of the ignition. (Clutch down, obviously). Turned on the ignition, and this noise occured before I had re-started the engine. I had the window open, and I reckon the noise was from the wheelarch, so may well be the ABS pump. It's definitely not fuel pump.

Does the abs pump have an electrical interface?
Does it pump up after engine start?
It must sense wheel rotation.

Any info on how this stuff works and what I can check out would be most welcome.

Cheers
Russell

rmcdonnell · 06-05-2008, 02:27 PM

OK, it is the ABS pump making a noise.

Test Cycle acording to Mitchell:
A test cycle runs in the ABS control unit when ignition is on, and another runs at a road speed of 3mph. ABS test at 3mph can be felt, since the pump in hydralic unit will run briefly. Test cycle repeats each time vehicle accelerates.

I wonder if I have a brake fluid leak, or if the pump is shot. Maybe, it has had a knock and is resonating against the wheel arch. I shall investigate more at the WE. Anyone else had ABS pump noise and cured it without replacement..?

cheers
Russell

bazar01 · bazar01's Garage

Quote:

Originally Posted by Tishabet

I agree, probrbaly your ABS pump.

Bazar01: what "went" on your ABS and how did you disable the system?

There is a T40 connector in the electrical schematics under the dash in the passenger footwell. I think it has about 4 wires and it's a black connector just above the DME.

Tishabet · 06-06-2008, 06:45 AM

Quote:

Originally Posted by bazar01

There is a T40 connector in the electrical schematics under the dash in the passenger footwell. I think it has about 4 wires and it's a black connector just above the DME.

Good to know, thanks!