C4 Question: how many have changed the brake accumulator?

code7rpd · 09-13-2009, 01:43 PM

Out of curiosity - how many have changed the C4 accumlator ball out as preventative maintenance or due to problems? I read that they hold nitrogen pressure which is slowly lost over time. Considering it is not too exepnsive of a part, would it be worth replacing on a car that has about a 150k on the clock? My pump runs for about 60 seconds on start up after sitting overnight after a full brake bleed (brake lines, accumulator, and drive block). Reading the posts here it seems that some pumps run longer and others for less time so I was curious if anyone changed this part out and got a dramatic improvement in how long the pump cycles.

DaveK · 09-13-2009, 01:59 PM

Mine was changed in an attempt to solve ABS problems - probably about 7 years ago now. The pump did run less for a short time afterwards, but that didn't last long.

Unless you know you've got a fault, I'd leave it alone.

John D. · 09-13-2009, 03:45 PM

Over 120K on our '89 C4 - and nope..? I'm in Dave's camp on this... If it's working - I'd leave it alone.

John

DAVISRILEY · 09-13-2009, 08:45 PM

I replaced mine in a misguided attempt to fix a soft pedal issue at 98k. Did not need it, and made no difference. Try flushing everything out properly, with a hammer. Probably will have a shorter pump run time, I know I did.

roadsleeper · 09-14-2009, 02:17 AM

I changed mine because it was holding around 40% of what optimum pressure should be (don't remember what that number is anymore). I know I'm preaching to the converted here, but guys, even if you don't track your cars, bear in mind that how well the braking system holds up could save your butt. My car is an '89 and I have changed the accumulator as well as the brake booster pump because the parts are just plain old.

code7rpd · 09-14-2009, 03:12 AM

All good points - does a special tester have to be used for checking the pressure?

Rocket Rob · 09-14-2009, 08:28 AM

My C4 has its original accumulator. I did change the ABS boost pump about 12 years ago when a faulty relay burned out the pump.

09-13-2009, 01:43 PM	#1
code7rpd Addict Rennlist Member Join Date: Feb 2003 Location: Bay Area, Ca Posts: 55	C4 Question: how many have changed the brake accumulator? Out of curiosity - how many have changed the C4 accumlator ball out as preventative maintenance or due to problems? I read that they hold nitrogen pressure which is slowly lost over time. Considering it is not too exepnsive of a part, would it be worth replacing on a car that has about a 150k on the clock? My pump runs for about 60 seconds on start up after sitting overnight after a full brake bleed (brake lines, accumulator, and drive block). Reading the posts here it seems that some pumps run longer and others for less time so I was curious if anyone changed this part out and got a dramatic improvement in how long the pump cycles.

09-13-2009, 01:59 PM	#2
DaveK Addict Rennlist Member Join Date: Nov 2001 Location: Surrey, UK Posts: 3,850	Mine was changed in an attempt to solve ABS problems - probably about 7 years ago now. The pump did run less for a short time afterwards, but that didn't last long. Unless you know you've got a fault, I'd leave it alone. __________________ Dave '90 964 C4 '02 996 TT

09-13-2009, 03:45 PM	#3
John D. Rennlist Join Date: May 1998 Location: Somewhere.... Posts: 8,631	Over 120K on our '89 C4 - and nope..? I'm in Dave's camp on this... If it's working - I'd leave it alone. John __________________ '95 993 C4 '89 964 C4 (<- Jen's...) '68 911 L (<- Jen's...) *Don't Panic* - it's just me, John D.(<- Jen's...) posting as me.... Team Geek & Sunday Driver for “Hey, Wait For Me Racing” Giving new meaning to the term *“Frozen Rotors”*

09-13-2009, 08:45 PM	#4
DAVISRILEY Moderator Rennlist Member Join Date: Apr 2004 Location: bloomington, IN Posts: 1,052	I replaced mine in a misguided attempt to fix a soft pedal issue at 98k. Did not need it, and made no difference. Try flushing everything out properly, with a hammer. Probably will have a shorter pump run time, I know I did. __________________ 1991 C4-Guards Freaking Red Have now fallen off the slippery cliff, no end to the modifications in sight..... 1972 911-Umm, never mind. Rust is pain. 1994 Celica-Ugliest car I have ever owned. Finished the 24 Hours of Lemons at Nelson Ledges. Yee-haw! 1982 LeCar-Next Lemons car. I think there was some drinking involved in this decision.

09-14-2009, 08:28 AM	#7
Rocket Rob Addict Rennlist Member Join Date: Aug 2001 Location: Nashua, New Hampshire, USA Posts: 2,407	My C4 has its original accumulator. I did change the ABS boost pump about 12 years ago when a faulty relay burned out the pump. __________________ Rob '90 C-4 Cab (daily driver-230K miles on original engine) '91 C-2 Coupe (weekend toy/DE car) '91 Honda Civic Si (winter-mobile)

09-14-2009, 02:17 AM	#5
roadsleeper User Join Date: May 2006 Location: Singapore Posts: 223	I changed mine because it was holding around 40% of what optimum pressure should be (don't remember what that number is anymore). I know I'm preaching to the converted here, but guys, even if you don't track your cars, bear in mind that how well the braking system holds up could save your butt. My car is an '89 and I have changed the accumulator as well as the brake booster pump because the parts are just plain old.

09-14-2009, 03:12 AM	#6
code7rpd Addict Rennlist Member Join Date: Feb 2003 Location: Bay Area, Ca Posts: 55	All good points - does a special tester have to be used for checking the pressure?