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sportsmartcar

Brake Booster

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Good evening all.I'm wondering where the brake booster is located. I need to change the vacuum lines on it as I have encountered the limp mode, no boost syndrome. I have also been experiencing a hard brake pedal condition. I need excessive pressure for braking, sometimes. Sometimes its a grabby pedal. Google is my friend, and this is where I have decided to start.I appreciate all your help.Debbie

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It's under the floor behind the brake pedal.But the symptoms are likely unrelated, because the booster is powered by a vacuum pump, unrelated to turbo boost (or lack thereof).

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Vaccum on the smart comes from a vacuum pump if it is CDI - so that won't be the source of any engine codes as it doesn't bleed off any manifold vacuum as there isn't any on a diesel. Good luck with the trouble shooting - hopefully the culprit steps up and is found easily.Cheers,Cameron

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Mine has just started giving me vacuum problems where the pedal is hard at idle and softens up when the revs go up. It's only noticeable when stopped at a light or in heavy traffic and not when driving normal speeds. I'm guessing there is a pinhole leak or some cracked line somewhere? I hope it's not a problem with the vacuum booster! Anyone else have this problem?

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I believe this is a picture of it from under the car with the belly pan removed.post-6582-1288742338_thumb.jpgCheck the brake fluid reservoir level and for leaks. If the level is up and there are no leaks then you should focus on the vacuum lines...Gord

Edited by gordo.bernard

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I believe this is a picture of it from under the car with the belly pan removed.post-6582-1288742338_thumb.jpgCheck the brake fluid reservoir level and for leaks. If the level is up and there are no leaks then you should focus on the vacuum lines...Gord

Could it also mean that I need a brake fluid change?Thanks, Debbie

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Brake fluid problems usually have the opposite effect - pedal gets scary soft when the brakes get hot (not an enjoyable feeling because the brakes being hot usually means you need them) as the water in the fluid flashes off to a gas at a lower temperature than brake fluid. Doesn't hurt to change brake fluid at least once every 2 years - I used a vaccum bleeder - suck the old fluid out of the reservoir and refill it with new -work your way from the back passenger side to the front driver's side - keep the fluid topped up in the reservoir - this sucks the old fluid and any crud that has settled in the cylinder/caliper. Brake fluid is hydroscopic - that it it absorbs water - as well there is a bit of crud from the seals wearing - keeping this out of the system makes it happier. I don't know if you can pedal bleed the car or not with the ABS - I know the factory way is to use a pressure bleeder (mainly because you don't have to check the reservoir - it keeps filling it). Cheers,Cameron

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Brake fluid problems usually have the opposite effect - pedal gets scary soft when the brakes get hot (not an enjoyable feeling because the brakes being hot usually means you need them) as the water in the fluid flashes off to a gas at a lower temperature than brake fluid. Doesn't hurt to change brake fluid at least once every 2 years - I used a vaccum bleeder - suck the old fluid out of the reservoir and refill it with new -work your way from the back passenger side to the front driver's side - keep the fluid topped up in the reservoir - this sucks the old fluid and any crud that has settled in the cylinder/caliper. Brake fluid is hydroscopic - that it it absorbs water - as well there is a bit of crud from the seals wearing - keeping this out of the system makes it happier. I don't know if you can pedal bleed the car or not with the ABS - I know the factory way is to use a pressure bleeder (mainly because you don't have to check the reservoir - it keeps filling it). Cheers,Cameron

Thanks for the info. I guess I know what I am doing this weekend...LOL Debbie

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If you don't have a vaccum bleeder they are available at most car places and Princess Auto etc. - pretty cheap - around $60 for a good one - and you can use if for other stuff like vaccum/pressure testing switches, sucking bubbles out of the cooling system (when you change the anti-freeze once every two years - use the Mercedes stuff - it has the right additives to prevent the alloys in the engine from corroding) and of course bleeding the brakes.Cheers,Cameron

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Thanks Gord, I will trace the vacum line from the pump to the booster. I haven't had a chance to get under there but might try this weekend. I hope it's not a worn pump or problem with the booster! I wonder if the plastic tube has worn through from rubbing on something from the vibration of the motor like what happens with the rubber intake hose from the EGR to the intake manifold or the vibration wear on the core tubes of the intercooler from the shroud? There is so much destructive wear from vibration on hoses rubbing, etc.

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I may be wrong, but I was under the impression that the smart was using a DOT 4 (silicone) brake fluid. Can anyone confirm this? I was planning to flush mine next summer and have always used DOT 4 in my other vehicles.

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DOT 4, which is not silicone. DOT 5 is silicone and does not work with ABS, so they say...

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DOT 5 has some other effects not so great with some brake components - DOT 4 will serve well beyond the needs of the use of a smart (unless you have a 4 tonne trailer hooked up to it going down the Coquihalla).Stick to DOT 4 - and make sure it is fresh - stuff stored will absorb the water out of the air ever time it is opened - part of the reason they put the rubber thingy in the reservoir (keeps air out). Besides DOT 4 is a heck of a lot cheaper than DOT 5 so you can afford to flush the system once a year and still not be hurting for cost.Cheers,Cameron

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Be aware too that DOT 5 is NOT compatible with any other brake fluid so your system must be thoroughly cleaned and dried first with no residue of the previous fluid.

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Got this problem today while putting the engine back up... 

I was pretty upset at myself because I didn't take enough precautions.

Well, mine broke nearer the valve and I tried to glue it back with a really sturdy stuff : Q-bond 

But I think some of the liquid got inside the valve and glue it in place, at least a little.

I drove it a little and find the brake pedal is hard but not too hard, it reminded me when cars was not sold with power brake. It is almost impossible have the abs work on clear road, but I succeed on gravel. 

I do have a spare part coming from a second smart 2005 car but the part is not the same, they changed it on the 2006 model I figured out.

So bad!

 

I'm thinking, should I cut the line and put a connector like this in between.

 

The problem is that I'm unable to remove the broken connector, how did you do it?

 

 

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14813103_10154538795247667_673729208_o.jpg

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try a heat gun,,,, and some elbow grease

 

or if youre talking about the nub squeeze the ring in the right spot and pull

Edited by LooseLugNuts

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