Diff lock sticking on 964
Discussion
The last couple of days the warning lights for the differential locks and ABS have been slow to go out on my 1991 Carrera 4. Today it even came on again after driving for about 3 miles (I pulled over and had to hold the switch for a long time before the lights went out again)
Anyone got any idea what could be going wrong or had a similar experience?
I understand that driving with them engaged places a huge strain on them round corners, especially in the dry, and should be avoided.
Anyone got any idea what could be going wrong or had a similar experience?
I understand that driving with them engaged places a huge strain on them round corners, especially in the dry, and should be avoided.
Hi Stig (is it really you...?)
Are you sure the diff is actually sticking or is it the warning lights and buzzer that are illuminating? I have a 1990 C4 and have a similar sounding fault - intermittent usually after 30 - 40 minutes driving most often at constant speeds. The warning light comes on but the car is unaffected. There is a running thread on the 964 technical site with a few others who have had the same fault. Some suggested getting the sensors checked while others suggested that the distributor might be effecting the warning circuitry through some archane Porsche wiring logic. Suffice to say, I spoke to the my service dealer who also serviced the car about a year ago for the previous owner. He also had the fault occasionally and the car was checked out (no fault found but then he like me didn't want to pay out a fortune for diagnostic work if it was just a warning light). the car's done 12,000 miles in the past 18 months and had no adverse effects other than driving around with the wanting light on so I'm putting up with it until something major needs doing and they can muck about with the ABS sensors all they want.
Not sure if this helps but other than being a bit of a pain, it hasn't been a problem and from all I've heard you would really know there was one if the diffs really were locked!
Andy
Are you sure the diff is actually sticking or is it the warning lights and buzzer that are illuminating? I have a 1990 C4 and have a similar sounding fault - intermittent usually after 30 - 40 minutes driving most often at constant speeds. The warning light comes on but the car is unaffected. There is a running thread on the 964 technical site with a few others who have had the same fault. Some suggested getting the sensors checked while others suggested that the distributor might be effecting the warning circuitry through some archane Porsche wiring logic. Suffice to say, I spoke to the my service dealer who also serviced the car about a year ago for the previous owner. He also had the fault occasionally and the car was checked out (no fault found but then he like me didn't want to pay out a fortune for diagnostic work if it was just a warning light). the car's done 12,000 miles in the past 18 months and had no adverse effects other than driving around with the wanting light on so I'm putting up with it until something major needs doing and they can muck about with the ABS sensors all they want.
Not sure if this helps but other than being a bit of a pain, it hasn't been a problem and from all I've heard you would really know there was one if the diffs really were locked!
Andy
Hi Andy, welcome to the forum.
I'm pretty sure the diffs are actually locked as it always feels less willing to turn and the turning circle is even greater than normal, but then that could always be just psychological.
What's the difference between the red light on the dash and the orange light near the switch?
P.S my handbook's in German and I don't speak any!
I'm pretty sure the diffs are actually locked as it always feels less willing to turn and the turning circle is even greater than normal, but then that could always be just psychological.
What's the difference between the red light on the dash and the orange light near the switch?
P.S my handbook's in German and I don't speak any!
The system pressure switch controls the warning light, if the pressure side has a problem that may explain the light being reluctant to go out - is the pump noisier than normal? is the pump running hot?
The diff locks can be triggered by incorrect tyres - Non N rated, incorrect size or non genuine wheels - Incorrect dimensions.
I have had cars with similar issues that have been as simple to fix as a wheel swap......
With regards to carrying on driving the car with the light on, I have known 964's to smash their clutch couplings for the front drive if the lock 'drops in' at speed......
The diff locks can be triggered by incorrect tyres - Non N rated, incorrect size or non genuine wheels - Incorrect dimensions.
I have had cars with similar issues that have been as simple to fix as a wheel swap......
With regards to carrying on driving the car with the light on, I have known 964's to smash their clutch couplings for the front drive if the lock 'drops in' at speed......
Globulator said:
First simple thing to do is to change the oil, never does any harm and often improves a whole bunch of things at once..
Good idea had a look through the SH and it doesn't look like it's been done before, I've got it booked in at a Porsche racing specialist near Shrewsbury on Monday. Any ideas what it should cost? Should I get them to change the diffs oil too whilst they're at it?
iamthestig said:
Good idea had a look through the SH and it doesn't look like it's been done before, I've got it booked in at a Porsche racing specialist near Shrewsbury on Monday. Any ideas what it should cost?
No idea about cost - shouldn't be that much though. Phone to check if you want something like Mobil1 in the engine as you may end up supplying it! iamthestig said:
Should I get them to change the diffs oil too whilst they're at it?
I meant change the diff oil in my post
I had it in today for it's gearbox and diff oil change. To be fair it's not really sticking on anymore (only a couple of seconds after starting up from cold).
Was charged a very reasonable £85 all in, and they gave the car a once over whilst it was up on the ramp.
Looks like it's gonna need before long:
-engine oil cooler leaking
-both lower cam covers leaking oil
-all 4 cv joint gaitors split
-both lower front wishbone bushes split
The oil cooler is the one that needs more urgent attention, they say they may be able to get it re-cored but then the car will be off the road for several days. I'd prefer to source a new one at a reasonable price. If anyone knows of a good place to buy one mail-order the advice would be much appreciated.
Was charged a very reasonable £85 all in, and they gave the car a once over whilst it was up on the ramp.
Looks like it's gonna need before long:
-engine oil cooler leaking
-both lower cam covers leaking oil
-all 4 cv joint gaitors split
-both lower front wishbone bushes split
The oil cooler is the one that needs more urgent attention, they say they may be able to get it re-cored but then the car will be off the road for several days. I'd prefer to source a new one at a reasonable price. If anyone knows of a good place to buy one mail-order the advice would be much appreciated.
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