Matdragon

Braking Issue

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Hi Guys,

New here, this forum has been a wealth of information for me so far and finally decided to register!

I bought an IS200 quite a while ago as a temporary get me around car whilst I fix up my others, but have ended up growing very fond of it and now have an appreciation of all Lexus motors!

However, the car is currently driving me crazy! I had the common seized front brakes issue so replaced both of the front calipers with 2nd hand replacements and this is when all my problems started.

After fitting the calipers and bleeding all the calipers, my brake pedal pushes down around half way and then slowly sinks all the way to the floor. When driving, i have hardly any breaking pressure until I pump the pedal a few times then it will stop very quickly. However after a short period of time (30 seconds) all the pressure will dissipate again. Things I have tried to resolve this issue which have had no effect:

- Bled all the brakes & Vacuum bled the ABS unit.

- Replaced the master cylinder with another which turned out to be the wrong one, which after a few pumps locked the brakes on completely until releasing the pressure from a caliper.

- Put original master cylinder back on, bled calipers & Vacuum bled ABS again.

- Replaced Booster & Master cylinder with the correct one, bled brakes & vacuum bled ABS again.

My brakes are still the same and i'm at a complete loss! Really want to get my car back on the road.

Any help would be greatly appreciated and once fixed I look forward to contributing to the forum with a working Lexus of my own  :laughing:

Many thanks,

Matt

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Hi Matt

Typically your issue would be faulty seals in the master cylinder. Are you losing any fluid?

Take a look at this old thread:

 

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I don't know if this helps but I had the same problem with my other car which is a VW Bora TDI. I bled the braking system a couple of times, always ensuring that the fluid exiting the calipers was clear of air but I could not get a hard pedal without pumping. That is until I discovered that the master cylinder had a bleed nipple as well. Fitted the bleed tube and opened it up and out gushed a load of bubbly fluid.

Brakes have been fine ever since. Maybe  your Lexus has a similar bleed nipple or maybe not but worth checking.

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Hi Guys,

Thanks for your replies I appreciate the help.

I'm not losing any fluid the reservoir always stays at the same level.

I was so sure it was the master cylinder at fault, I just can't believe that the replacement I've got is just as bad as my original one! I read somewhere that the process of manually bleeding the brakes by pushing the brake pedal can be what causes the master cylinder to fail, as it pushes the piston further than it would usually travel with normal braking so hits all the crud that's collected in the cylinder and messes with the seals. Perhaps the same thing happened to my replacement!

I bled the new master cylinder by getting another person to push the pedal whilst I tweaked the hardlines to push any air out, a little did then just fluid.

Does anybody know where I can buy a master cylinder re-built kit / new seals? Now that I have 2 I can take my old one apart, properly clean and repair it then hopefully it will fix my issue! Problem is I can't find a seal kit anywhere online.

Many thanks.

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04493-53010 is the part code for the master cylinder kit - not sure what is included.

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Another possible cause can be due to pushing the caliper pistons back without  releasing the bleed nipple, this can result in turned seals in the master cylinder. If you have access to a pressure bleed kit this may also be beneficial as the fluid is forced through ensuring all the air is removed.

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Sorry for the very late reply, I eventually gave up with this as I realised the Sills were rotten so the car was not worth fixing anyway, But really appreciate the replies and advice!

Ended up buying an EP3 as a temporary car, but have now bought an Is200 Sport as I missed my Lexus! Just scared to touch the breaks when they will need attention in the future considering how badly it ended up with my old Lexus haha!

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I've tried loads of different 'bleed kits' without satisfactory results and called it a day with them, the best system I made up myself from the trigger part of one of those trigger spray bottles for household cleaners attaching the hose and caliper adapter to it, open the nipple and squirt into a jar, worked a treat and no spongy brake afterwards but you do need to keep an eye on the fluid level of the MC.

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