Poor brake pressure after front hose replacement
Discussion
I have just had the front brake hoses replaced on my XJR8 with standard brakes (not Brembo) after it failed the MOT. The pedal now stops the car but isn't firm like it was before. On pumping the pedal it firms up. The garage are telling me that it could be the master cylinder. It sounds like air in the system to me. They have used about 5 litres of brake fluid and a pressure bleeder but it still isn't right.
I read a post that suggested unbolting the calipers and rotating them until the nipple is pointing directly up, then bleed. Any other ideas before I ask them to try a second hand master cylinder?
I read a post that suggested unbolting the calipers and rotating them until the nipple is pointing directly up, then bleed. Any other ideas before I ask them to try a second hand master cylinder?
You might try a vacuum bleeder -- mityvac alike. Cheep as chips on eBay and a smear of silicone grease to seal round the nipple when sucking.
Sounds like they just screwed up.
Master cylinders are usually surprisingly cheap (if not, a rebuild kit will be available) -- try brakeparts uk, etc. I'd not mess with a s/h one.
But it does sound like classic air-in-the-system-itis.
Sounds like they just screwed up.
Master cylinders are usually surprisingly cheap (if not, a rebuild kit will be available) -- try brakeparts uk, etc. I'd not mess with a s/h one.
But it does sound like classic air-in-the-system-itis.
Air in the system will give a springy pedal with a lot of travel. A knackered master cylinder can usually be diagnosed by maintaining a constant pressure on the brake pedal. If it slowly sinks to the floor the master cylinder is knackered or you have a fluid leak which should be obvious. If it stays in the same position then the chances are the cylinder is OK.
Jaguar steve said:
Air in the system will give a springy pedal with a lot of travel. A knackered master cylinder can usually be diagnosed by maintaining a constant pressure on the brake pedal. If it slowly sinks to the floor the master cylinder is knackered or you have a fluid leak which should be obvious. If it stays in the same position then the chances are the cylinder is OK.
Exactly! I was advised by a BMW indy regarding a Z4M to operate the pedal at the same time as pressure bleeding to ensure difficult air bubbles are dislodged.Gassing Station | Jaguar | Top of Page | What's New | My Stuff