red-i

Hi Everyone, Picked up my 996 turbo which went in for a Secondry air leak which come up on the fault codes at opc , now car is making a droning noise on startup/cold for about 30sec , and every 15 mis or so !! never happend before, called porsche, and they asked to bring the car back on friday, but i thought id pick your brains as to what it can be ?? before i go back !

Any help greatly appreciated

Thanks

"02996ttx50

i would check the pentosin level near the ps reservoir in the engine comp, as it sounds like to you may be "low" and the system is trying to tell you. any hard lock turn groan? e.g. low ps fluid sound?

red-i

Hi 02996ttx50

That was my first point of call and the power steering fluid was at max level ,, i had a secondry pump fitted a few months ago , was wondering if that would make the noise ? It dosnt make any pump/droning noise on full locks only on cold startups , but yesterday did it when it reached running temp

"02996ttx50

my first guess was all i've got! are you talking about a secondary bosch fuel pump!?

the pent level dipstick has as you know a hot/cold level line(s) but i'm not sure how accurate they might be. but if can see fluid in that res? i figure im ok. so im out of my depth on this one. hard lock "groan" is ( as you know ), *usually* low fluid.

Macster

Nothing jumps out at me.

I would have offered a noisy replacement SAI pump but the noise appearing every 15 miles or so has me going "Huh?"

A low power steering fluid level is a good possibility. There's a right way to check this. Here's some cut/paste from the Turbo factory manual:

Power steering: checking the fluid level General
Damage to the power steering is caused by a shortage of oil in the hydraulic system. Even small leaks can cause the fluid to escape and damage the servo pump as a result of the high oil pressure occurring in the hydraulic circuit.
Grunt−like noises that can be heard when the steering is locked, or foam formation in the reservoir indicate a shortage of oil and/or that air has also been sucked in. Before filling the reservoir, any existing leaks must be eliminated on the suction side. Alternatively, the defective part on the pressure side should be replaced.

For the Turbo, not only the power steering is supplied from the collective supply tank −A− located in the engine compartment, but also the hydraulic clutch boost.

The supply tank for GT2 has a different form. It is located in the engine compartment.

Only Pentosin CHF 11 S may be used in the reservoir. Pentosin CHF 11 S can be ordered with the following part number: Quantity supplied 1 litre = 000.043.203.33.

Note
• There is a second tank for clutch operation for the Turbo. This container is located in the luggage compartment (under a cover).

There are two marks on the dipstick located on the reservoir cap. One side bears the mark Cold for a cold engine (approximately 20° C) and the other Hot for a hot engine (approximately 80° C).

• Check the fluid level (Pentosin CHF 11 S) with the engine stationary and cold (approx. 20 °C).

CAUTION
Danger of damage to property if too much Pentosin CHF 11 S is filled or if it comes in contact with the coolant hoses when topping up or filling in.

• Observe the following specifications in order to avoid overfilling and thus overflowing.

• Multiple steering operations (manoeuvring) or/and actuating the clutch with the engine switched off change the fluid level in the reservoir (actuating the clutch is not valid for the GT2). Fluid level rises.

In this case, the engine must be run for approx. 20 seconds immediately prior to the fluid level check.

• If coolant hoses come into contact with Pentosin, thoroughly clean them with water IMMEDIATELY.

• Replace visibly swollen coolant hoses.
1. Start engine and run it at idle speed for approx. 20 seconds. Switch off engine.
2. Open the engine cover.
3. Open reservoir cap.
4. Wipe off the dipstick. Close and then reopen the cap. The fluid level should lie in the hatched area beneath the "Cold" mark (mark = maximum level at 20° C). Top up with Pentosin if necessary. *The upper "Hot" mark is intended for a fluid temperature of 80° C.
• Do not add too much Pentosin! The respective marks are for the maximum fluid level at the "COLD" or "HOT" temperature.
• If assembly work was performed previously, check the fluid level with the engine idling and without operating the steering.

Since the car was just worked on and is due back in a few days you might just let the car sit and let the OPC sort this out. If you attempt any diagnostics and something gets worse, if you cause any collateral damage, the OPC may be reluctant to address any collateral damage.

ANJ-911

Macster, when checking the PS fluid level when the engine is in a "Hot" condition, the engine should be off but at full operating temp. correct?

Macster

That is my interpretation. In either case, cold or hot, the engine should be off when checking the power steering fluid level.

The steering wheel should not be turned after the engine as shut off and the clutch pedal should not be depressed as these things can affect the power steering fluid level.

Be careful that you do not get any of that fluid on anything.

"02996ttx50

as i understand the dipstick ( lol no jokes pls ) that's the reason there is a "hot" and "cold" measurement line.

after running the car check with engine off and ensure fluid is at HOT line or near it.

calandri

Guys,
Have the same issue. Always when slowing down in second gear. Noise is removed after press the clutch.
Any idea?
Thanks

Kevinmacd

What were the fault codes to begin with?

Macster

You sure the symptoms are the same as those posted by the OP?

My first thought is if the noise is present but goes away when you depress the clutch it is related to clutch (power steering) fluid level.

You can check the fluid level easy enough.

Check the panel ahead of the driver under the front trunk lid? Do you see any fluid stain?

Another possibility is the noise is coming from the transmission or more likely the rear end.

When you depress the clutch this takes away some of the load being generated in the tranny/diff as engine compression is longer supply a braking action.

I have to mention too there is a very large 6-speed transmission and differential located right behind/under the rear of the cabin and some drivetrain noise will intrude.

Has a tech heard the noise? What does he have to say about it? Maybe it is normal?

ANJ-911

Found this TSB which may be related to what calandri is experiencing, maybe the noise has something to do with the pressure control valve in the power steering receiver they're referring to in the TSB?

red-i

HI Chaps,, Sorry for the late reply,,

the noise is on startup , comes from the back of the car , sounds like a blowing exhaust manifold but isnt as the noise stops after car has run for about 5 mins, sounds like some sort of pump, had a fault code with secondry air system and OPC changed a valve if that help diagnose, Can it be a pump that sucks in hot air to intake when engine is cold and then again if emissions are high / unburnt mixture ? which is y it maybe comes on after about 15 mins ??

Macster

I am aware of that source of noise and in fact have had it addressed in my 03 Turbo. (New power steering tank.)

But the OP posted his car had the same issue as the OP's and the OP titled his first post with "droning/pump noise", which does not describe a whistle.

However, it may be possible the problem manifests itself with something other than a high pitched whistling noise so if the noise appears after the car is warmed up and goes away when the clutch pedal is depressed and the power steering fluid level is ok and if the clutch slave cylinder is not showing any signs of leaking then the power steering tank and its valve has to be considered.

red-i

I will try get a sound file up