brake / clutch booster problem - GQ TD42

[Snarba]

Hi there I don't seem to be getting enough pressure from the vacuum when the vehicle is idling...I get one "turn" of the brakes but if I need to use them again before I have revved the motor they are rock solid. With the motor above idle the brakes work fine...makes for some fancy foot work in traffic I can tell you I have checked for leaks and even tried a different brake booster but I think it must be the vac pump itself....the clutch booster hasn't worked since I bought it. any advice ? ( apart from stop driving it )

[ozy1]

you could remove the vacume pump off the rear of the alternator and check to see if the vanes are sliding freely in the housing, cause if i remember correctly it is a vane pump set up, and sticking vanes will reduce vacume,

[coxy321]

I had the same isue on my GQ just recently, but it was due to a low idle speed (under 400RPM from memory) probably due to recent injector replacement and some servicing. I have bumped the idle speed up to 600RPM and all is good, however i dont think my car is producing as much vacuum as it should be.

[suggy126]

Check your lines too, cause if you get a pump out of the barke then the vacuum is probably working but not holding, if there ios a leek you'll only have vacuum when the engine rev's are up, also check a line hasn't come off either your alternator or vacuum tank.

Suggy

[eighty8]

Have a look at the small vac lines that control the a/c idle up solenoid. They have a tendancy to split and fall off. Happened to me not long ago, coming down a hill and the brakes weren't pulling up as good as normal. Checked under the bonnet and the line was off at the back of the vac pump . It runs along the firewall to a solenoid near the wiper motor then to the IP .

[coxy321]

Have a look at the small vac lines that control the a/c idle up solenoid. They have a tendancy to split and fall off. Happened to me not long ago, coming down a hill and the brakes weren't pulling up as good as normal. Checked under the bonnet and the line was off at the back of the vac pump . It runs along the firewall to a solenoid near the wiper motor then to the IP .

Yep - i'll back that up too. Mine appears to be a tad short, so i'll be replacing mine this week.

[Snarba]

cool will check that tomorrow morning, thanx. Was also thinking that if I bypassed everything and ran a hose from the vac to the brake booster I would be able to rule out air leak. I have a feeling it's the actual vacuum pump because a while back when I fixed an oil leak I noticed the vanes were fairly worn. Thanx for all the advice

[Snarba]

Have a look at the small vac lines that control the a/c idle up solenoid. They have a tendancy to split and fall off. Happened to me not long ago, coming down a hill and the brakes weren't pulling up as good as normal. Checked under the bonnet and the line was off at the back of the vac pump . It runs along the firewall to a solenoid near the wiper motor then to the IP .

Hmmm couldn't find any solenoids inline, nothing near the wiper motor at all. It goes from the the vac to a small cylinder where it is split for the line to the clutch master cyl and the other straight to the Brake booster. Couldn't see any smaller lines at all, also can you please tell me what the IP is? thanx for all the help

[coxy321]

Have a look at the small vac lines that control the a/c idle up solenoid. They have a tendancy to split and fall off. Happened to me not long ago, coming down a hill and the brakes weren't pulling up as good as normal. Checked under the bonnet and the line was off at the back of the vac pump . It runs along the firewall to a solenoid near the wiper motor then to the IP .

Hmmm couldn't find any solenoids inline, nothing near the wiper motor at all. It goes from the the vac to a small cylinder where it is split for the line to the clutch master cyl and the other straight to the Brake booster. Couldn't see any smaller lines at all, also can you please tell me what the IP is? thanx for all the help

IP: injector pump.

I can take a photo of the vacuum line for you tomorrow if you need. Basically when you turn the A/C on it makes the engine fast-idle to compensate for the extra load the A/C pump has created.