Tarago Brake Pressure Fade - PLEASE HELP :)

Submitted: Monday, May 03, 2010 at 11:07
ThreadID: 78189 Views:3730 Replies:6 FollowUps:3
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Hey guys, Ive been looking at this on and off for a few weeks now and am just about ready to admit defeat, but this is the issue:

Vehicle: 94 Totoya Estima (jap imported AWD turbo diesel Tarago)

Problem: When braking brake pedal pressure is poor and front left brake does not operate properly. Under heavy braking the rear wheels and front right will lock, front left does not, but pedal will still fade away to the floor. This issue arose overnight - not a long lead in or anything.

Solutions Tried (on front left wheel)
- Brakes all bled / new fluid
- Brake pads replaced
- Rubber hydraulic hoses replaced
- New Seal kit on wheel cylinder
- When bleeding, brake pedal is HARD. You can have the pedal feel hard when car is stationary.
- Disabled power assist unit (remove vacuum hose), its harder work, but still slowly fades away, it just fades faster when enabled.

Driving Experience:
When driving the pedal feels soft, you put the pedal down and about 2/3 of the way into the travel it will lock the remaining three wheels, but the pedal continues to depress until it reaches the floor.

You can give it a few short pumps and it firms up, but still then fades away to the floor.


At first glance i'd say air in line, but they are well bled and definately not the issue.

I dunno, i'd rather not fork out for an actual mechanic to spend hours and hours troubleshooting it all over again so a peal of wisdom from you guys would be VERY APPRECIATED :)

Thanks,

Mark.
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Reply By: Member - Duncs - Monday, May 03, 2010 at 11:30

Monday, May 03, 2010 at 11:30
Before I give any advice let me say I am not a mechanic, never have been and never will be.

However, I have a natural inquisitiveness and tendency to thrift, that encourages me to have a look before I pay someone else to do the same.

Your problem sounds very much like air in the system, but it could be few other things too.

You say brakes all bled and new fluid, did you bleed the master cylinder? I once had a guy suggest this to me for a similar problem on an LH Torana. I can't remember how I did it but it did solve the problem.

The other thing it could be is a soft brake line. Some early jap bikes had this problem and replacing the brake lines with braided hoses made a huge difference.

You also say you put a new seal kit in the wheel cylinder. Did you pull the cylinder apart and give it a good clean before re-assembling it? And did you lubricate it. I had a calliper on the rear of my GQ that was slow to release. A good clean solved that problem.

Hope this is of some help. Like I said earlier I am no expert these are just some of the things I have had experience of over the years.

Duncs
AnswerID: 415203

Follow Up By: Fab72 - Monday, May 03, 2010 at 19:38

Monday, May 03, 2010 at 19:38
Well, for the record I am a mechanic and Duncs in right on the money. Sounds very much like a master cylinder problem.

The only other thing I'd be suspicious of is the brake calliper. You say you did the wheel cylinder......on disc brakes???? Mmmmm.

You also failed to mention if the van has ABS. If it does, it may be an issue with the ABS pump or circuits within. Guessing it doesn't because you say the other three wheels lock up.

If it were my car, I'd check the pressure at the master cylinder. Blow the lines out from the master cylinder down to the calliper with compressed air and flush through with some meths.

Clean the disc thoroughly to remove any oil or grease, and have a proper look at the calliper. No disrespect but for you to be asking for advice on this subject, I take it you're not a mechanic and so what you believe to be an overhaul of the calliper, might be nothing more than putting a band aid on a broken back.

As stated further down this post, not getting the brakes right could well kill you, your family or some other poor soul. Are criminal negligence charges and a criminal record cheaper than taking the car to a mechanic?

Sorry, but it really yanks my chain that you need a licensed electrician to put in a power point to save your own skin from getting zapped, but any Joe Blogs can stuff around with brakes on a car which has the potential to kill many more people. Stick to engine repairs, the worst that can happen there is that the car stalls or fails to start.
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FollowupID: 685429

Follow Up By: Member - Ian W (NSW) - Monday, May 03, 2010 at 21:43

Monday, May 03, 2010 at 21:43
Take your vehicle to a workshop that specialise in braking systems or the brand dealer.

It is plainly obvious that you are out your depth.

With all this playing about, it would appear that you are driving/testing your vehicle on public roads, if so you are placing other peoples at risk of injury or death.

You may find my reply offensive, however I spent too many years in the motor trade and the brake trade in particular to not call it as I see it.

Braking systems in today's motor vehicles are incredibly reliable in comparison to those of years ago, however the downside is that when things go wonky they can be extremely hard to diagnose. If you don't actually know what you are doing then don't try to guess it. How would you feel if your airline pilot posted hear asking advice as to get the plane back down on the ground?

It never ceases to amaze me that some people will fool around with systems that have the potential to kill themselves or others but when for instance, the TV, fridge or washing machine carks it, they just go out and buy another.
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FollowupID: 685450

Reply By: feathery - Monday, May 03, 2010 at 11:33

Monday, May 03, 2010 at 11:33
Look at it this way while you are driving around in a vehicle that has faulty brakes you are endangering my life and your own and every road user so with that in mind a mechanic is the cheapest and best option
AnswerID: 415205

Follow Up By: MarkDabner - Monday, May 03, 2010 at 11:48

Monday, May 03, 2010 at 11:48
nah mate.. it happened in the garage and it hasnt left the driveway or the 30 meter strip of road in front of my house for testing fixes.. we have another car we fit everyone into so its not been a drama. just dragging on a bit long now...
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FollowupID: 685366

Reply By: Member - Donks1 (NSW) - Monday, May 03, 2010 at 11:51

Monday, May 03, 2010 at 11:51
I tend to agree with Feathery. please don't guess with brakes.

It does sound to me, ( 12 years in B & C ) like a master cylinder issue.

As suggested bleed the master separately, first then the rest of the system. Pressure bleed would be best for this car. If this doesn't fix it, will be the BMC.
You've apparantly covered the rest of the system.

Steve
AnswerID: 415207

Reply By: MarkDabner - Monday, May 03, 2010 at 12:37

Monday, May 03, 2010 at 12:37
Thanks guys for the advice, i'll give it a run this arvo and post back how i got on..
AnswerID: 415212

Reply By: kiwicol - Monday, May 03, 2010 at 15:18

Monday, May 03, 2010 at 15:18
Hi, Sounds like 2 issues, i would replace master cylinder, and check the calliper that's not locking up to see if it has seized up. Col
AnswerID: 415225

Reply By: Member - Toyocrusa (NSW) - Monday, May 03, 2010 at 20:06

Monday, May 03, 2010 at 20:06
G'day Mark. Your problem sounds very much like the Master Cylinder has an internal bypass problem. The piston seals are allowing fluid to flow past under pressure. Suggest you either have it rebuilt by a specialised brake repairer or replace it with a new one. Regards, Bob.

AnswerID: 415258

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