rob0001

Got a noise that make me crazy and difficult to explain as all noises does.

The noise is best to be described as an air cooled 964/ 993 oil gurgling start-up noise. It is like an intermittent mechanical scraping/ grinding noise and hard to pinpoint from where originated.
It does this only at idle (cold engine more hot less) and only for a short period after engine start. It varies in loudness and frequency and not always or after a few second when started. I hear this only from inside the car with doors closed. Sticking my head inside engine bay nothing, listening with stethoscope on water pump, turbo oil pumps, pulleys etc. nothing, only the typical IMS chatter noise our engines have. Heater/ AC is switched off. Putting the gear (tiptronic) in D or R no change. Power steering servo oil is at level.

Recent changes, new K16/24 turbos, oil feed lines and an 5bar FPR.
Could it be the FPR return line pulsing noises? Any other ideas were to look for?

Kevin

Electric Air pump which is powered up on cold start. If the bearings are going out they will give you a high pitch whine.

"02996ttx50

i dunno about the noise. but boy, are you gonna love that 16/24 setup. woohoo.

rob0001

Kevin, thanks for suggestion it is not the air pump. Disconnected the electrical wire which did not stopped the intermittent noise. I now also hear this noise when driving hard, coming to a stop and let it idle. This will also trigger this noise for 20 seconds or so.

Pooked some more with stethoscope and I hear a similar scraping noise from the metal line seen in picture with arrow. This line is at right side behind/ below powersteering servo. Were is this line for and could this be a source to my intermittent noise?

Kevin

The line that you have pointed to is the RETURN fuel pressure line. It is coming from your FPR outlet and goes to your A/C fuel condenser, and then back to your fuel tank.

In that area you have the A/C compressor AND Power Steering Pump..

rob0001

Thanks and as I thought. Is it then possible that the FPR is not working correct and is pulsing high pressure fuel back to tank? This could be the reason I only hear this noise from inside car?

I also noticed that the fuel vent solenoid is ticking very loud (located behind diverter valves) and sometimes it does not tick at all... Normal to tick or not?

rob0001

Found the problem, it was the 5 bar FPR, changed back to the old 3.8 bar and no more noises.
The 5 bar was a new Bosch 5 Bar FPR. with part number B280550113/2). Can these fail or is it just bad luck?

Kevinmacd

Since you have mods was the 5 bar FPR put there to work with a tune? If so I suggest putting a 5 bar FPR back.

rob0001

It was indeed tuned on a dyno with the 5bar. I know I must take it easy till I got my new 5bar FPR.
I already see the LTFT up to 15% and higher AFR (14).