tbennett017

Good call on the sensors - Strega....

Scottish964

Could this happen just by starting the car as the car went from perfect to this in 10mins when i was washig it. How did you trace to accelerometers? how was this problem fixed?

I just took some photos of the car etc so ill get a link up to those as well soon. PDAS red light on dash comes on and if turn **** to right after 10 secs it comes on again with beeps. when i turn it, you can here noises as well. I think its going to need to go to porsche soon

speedcat

I had the same noises on my '89 C4. Turned out to be the power steering belt, most of the teeth were worn off.

Rangers FC!

joey bagadonuts

Gerard,

Were the tires recently replaced?

I experienced similar juddering after installing tires with diameters which exceeded the system's tolerance. In my case, I was using a combination that varied by greater than 1", specifically 235/40/17 (24.4") and 275/40/17 (25.7") front and rear. I simply replaced the fronts with 235/45/17's (25.3") and the problem went away.

Also, make sure the tires are properly inflated as that might cause a similar issue. Hopefully, it's as simple as that!

Strega(UK)

Problem was finally traced to accelerometers after two weeks checking everything else. Am not sure what the fix was but am glad I did not need a new one as I believe they are ridiculousls expensive.
The red light on the dash normally comes on after diff selection but should go out as soon as you drive off, if it doesn't then the diff may well be engaged.

As for the power steering, this does make an equally hideous noise but won't give you the big bangs and juddering that you get with the diffs being engaged. Is yours just noisy or do you get clunks and bangs??

cockyapple

Scottish 964


Hi,


If you need to send it to a mechanic to be fixed.....i cant praise Peter McAnna at Motortune in Shotts enough.........excellent service.......excellent prices

Cheers Steve

Scottish964

I get Bangs and juderings i get i have taken some photos although the battery ran flat and i couldnt get photos or video of whats happenin..

911 bad pics if u follow link i took random pics although i dont think they will help much

The tires havent been changed

tbennett017

OK.. with this sequence of error lights (dash board lights(last picture), I looked through the troubleshooting section of Adrian Streather's book... (if you can get one of these it will help you: Porsche 911 Enthusiasts Companion, for the 964 by Adrian Streather, Bentley Publishers)

The sequence in which these error lights come on is important.. DO THEY GO OUT AFTER A FEW SECONDS? OR DO THEY STAY ON?

There is a lot of typing to do to cover the whole topic for you.. but here is a paraphrase to get a few ideas...

If it is this sequence: ABS Light goes out after 2.5-5 secs and immediately comes back on with a horn = ABS unit has failed or ABS solenoid valve inside the ABS Hydraulic unit has short circuited

OR
ABS warning light goes out after 2.5-5 secs and stays out until 964 has reached 7kph, plus a few seconds, then comes on again = Wheel speed sensor problem, or ABS return pump in the ABS hydraulic unit has failed

Further notes from the book:
"These problems can also occur in the C4 system. The clue for the C4 owner is to notice which warning light comes on first. ABS first indicates an ABS fault and PDAS first indicates a traction control problem."

"Wheel bearing failure can also activate the ABS warning system..."

(Figure out which it is, and let us know here.. as there are procedures to follow in the book)

Also

Your PDAS light... does this go out after a few seconds, or is this the total error combination? (IE - do they all stay on like this, or go out after a few seconds?) If your PDAS light stays on (the one in the upper rt) then there are some things to check:

"Brake pressure reached 102 bars and is falling: DO NOT DRIVE THE CAR
Could be low fluid levels, or a failed seal in the hydraulic pump." Take out the carpet and the spare, and check the floor of the trunk for fluid. (not likely since you stated your fluids were okay.. but check this anyway.)

OR Pressure switch has failed, replace or test at a shop
Is the brake pump running? (do you hear a buzzing in the first 10 secs or so of the car running, in the front compartment near the bumper?) A failed pressure switch

We're getting closer.. pix help. BTW, Accelerometers can be located in the car, opened and cleaned. New they cost the first two newborn, but they can be cleaned, if they are the cause of your problems...

Get back to us on the sequence of lights.. it helps narrow it down. We'll get you fixed up.. chin up okay?

ormy

Another thought - are there any Rennlist members near Glasgow with a Scantool interface?

This might help identify the problem assuming there is an error code showing.

I'm afraid I can't be much help as I've got a C2. Good luck on solving the problem & keep posting.

choogh

My moneys on your diff locks.. there not disengaging, Just why this happened I cannot say, but you can drive the car, but slowly and only to a garage for examination. Try and cycle the diff lock switch on the center consul, if you are hearing a "clunk" every time you cycle the swith, the locks are working.
Make sure you leave them "OUT".. check, then check again.
Ciao
Charlie

pat056

Scottish964
Did you get it fixed?

Scottish964

No, havent had the chance this week. Today was first day i stepped into it again. Tried choogh's advise and the altenator belt snapped again, although when we had changed this the garage had supplied us with one slightly 2 big. So i had to push it back along the street. When doing this holding onto the lefthand side made a much bigger knock which you could feel through the bodywork than the right, although you could still hear it through.

Indycam

So the motor was turned off and you were pushing the car and it made the noise ?

Talk to me , send me a yes or a no .

altarchsa

Differential locks should not cause two fan belts to break. Check that alternator like I suggested. The only reason the belt would break is if the alternator/fan is binding. If the alternator shaft is broken, you can push the blade from side to side and feel a little movement, even with the belt on. Also, look for scrapes on the outer edges of the fan blade or around the interior of the housing. The alternator may still function intermittently due to a rough surface or an angled break in the shaft causing them to turn together.

When the pieces of the shaft dislodge so that the back portion of the shaft, with the fan, is carried only by the back bearing in the alternator, you get a binding of the blade on the housing and it burns the belt up, .... smoke, etc. It happened to me!

It's not unreasonable that a broken shaft could be causing a clunking noise.

Indycam

If he is pushing a non running car and gets the clunk , its not the motor / alt / ps pump .