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Cloudy Brake Fluid


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Morning all,

 

Could be a day of brake problems...

 

Went out for a run in the TR yesterday and by the end of the drive, the brake pedal was on the carpet before the brakes worked. Checked the brake fluid level and sure enough, its lower than before. This is on top of the system consuming about 300ml of fluid a few weeks ago when i had a similar problem, but no leaks. I now assume the servo is gradually filing up with brake fluid although nothing is dripping out in the foot well or the engine bay. The calipers and wheel cylinders are also leak free.

 

More worryingly, the brake fluid has gone cloudy. I guess its the seals slowly disintegrating and I now think the PO may have used Dot 5.1.

 

So i'm faced with swapping out the seals in the cylinders and calipers and I'm going to replace the master cylinder and servo as a precaution.

 

To ensure the system is de-contaminated, would it be best to bleed through with Dot 4 before starting any work, then bleed with fresh Dot 4 on completion?

 

And are all Dot 4 fluids the same? Halfords do Comma but is there a better alternative?

 

Cheers

 

Mal

 

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Hi Mal,

if you are already using DOT4 (or think you should have been) why are you concerned about DOT5.1 - it is the same as DOT4 but uprated for ABS.

 

The lost fluid sounds like it is going into the servo. Eventually it may well leak from between the servo and the MC - there is enough room just forward of this joint to hold quite a lot of fluid..

The servo may well be OK but the MC seals need replacing.

 

As DOT5.1 is the same group as DOT4 then I would not bother flushing.

However if you meant DOT5 (silicon) then flushing becomes interesting - where do you 'start and stop'

 

If it is DOT5 why not continue to use.

 

Roger

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Hi Roger,

 

Yes, I meant Dot 5, but I had already flushed through with Dot 4 after the initial problem a few weeks ago, where I assumed the car already used Dot 4.

 

I now appear to have Dot 4.55......

 

Cheers

 

Mal

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Hi Mal,

firstly you need to find the source of the leak. As there are no external leaks I would go for the MC.

Remove MC and fit new seals.

The servo may be OK - was it still working.

 

Regarding flushing. This is quite an issue and not normally done with DOT4 to get rid of DOT5. Most of the posts on here suggest Meths.

However you need to clean the whole system - MC and 4xSC, all the pipe work etc AND all the seals replaced.

 

Again, If you think it had DOT 5 in there then why not stay with it.

 

Roger

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Hi guys

Dot 3 must be used with all Triumph brake systems!
Or for complete new systems also DOT 5 Silicon.
DOT 4 is unfortunately not compatible with the back-up.
It is typical that very slowly the seals dissolve. To be seen in the light clouds in the container.
Only by chance did I get this information from ATE Brakesystems Germany.
Therefore do not be surprised if brake systems and clutch with DOT 4 leaks. And dark clouds float in the container.

Be careful when working on brakes

 

Ralf

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Hi guys

 

Dot 3 must be used with all Triumph brake systems!

Or for complete new systems also DOT 5 Silicon.

DOT 4 is unfortunately not compatible with the back-up.

It is typical that very slowly the seals dissolve. To be seen in the light clouds in the container.

Only by chance did I get this information from ATE Brakesystems Germany.

Therefore do not be surprised if brake systems and clutch with DOT 4 leaks. And dark clouds float in the container.

Be careful when working on brakes

 

Ralf

Sorry but thats not true, DOT4 has been standard in this country for a long time and is eminently suitable for our cars. It was originally brought out to provide more lubrication for the then new disc brake systems. Dot 3 is suitable for drum brakes.

Dont start on the Sillycon versus Normal fluid argument or we will be here for days!

Stuart.

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There is some truth in Ralf's assertions, particularly when referring to ATE brake fluids.

 

Dot 3, 4 or 5.1 as standards refer to the in-service performance of the fluid, and NOT its chemical composition. Sure Dot 4 like Dot 3 is glycol based, but with the addition of borate esters for example, typically absent from Dot 3 fluids. 5.1 typically has a smaller again proportion of glycol and rather more of borate esters and whatever else.

 

Utilising a higher standard of fluid (and by higher the primary factor implied is higher dry and wet boiling points) is unlikely to be a problem with brake components manufactured this side of the mid-1990s. Most 'classic' component will be of materials at least compatible with Dot 3 and 4 . . . . . but that does not necessarily imply compatibility with Dot 5.1, nor for that matter with Dot 5 silicon fluids. Use either at your own risk . . . . .

 

'New Old Stock' component is another matter, and brake seals manufactured back in the day when Dot 3 was the norm are more than likely to prove unsatisfactory under exposure to Dot 4, let alone 5 or 5.1.

 

I went through this in detail in the mid-90s as a motor factor, and consulted all the major brake manufacturers' technical departments. At the time, the views offered differed significantly between manufacturers, presumably reflecting the differing composition of their various fluid offerings, and as I recall ATE were probably the most emphatic about the necessity of using their Dot 3 rather than 4 with older vehicles.

 

As far as today is concerned, Castrol for example assert that their Dot 4 is compatible with all systems requiring Dot 3 or Dot 4 fluids, whereas ATE insist that their Dot 4 is suitable for systems specifying Dot 4 as OE only, and that older vehicles should utilise their Dot 3.

 

It is wise to be rigorous in checking the application parameters for whatever variety of brake fluid you choose to employ - as in checking the fluid manufacturer's website, for example. It is also, I would suggest, appropriate to check with the supplier of your brake component . . . . .

 

Cheers,

 

Alec

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Hi Alec,

 

So would that be any Castrol Dot 4 or do you know if there is only one type available now? I don't won't to go through this again!

 

Cheers

 

Mal

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Hi Mal,

 

see Castrol website - http://www.castrol.com/en_gb/united-kingdom/products/cars/brake-fluids.html

 

in comparison, check the ATE downloads -http://www.ate-brakes.com/products/brake-fluids/

 

When it comes to flushing, my own preference would be to first flush the system with meths, then blow through compressed air (an electric tyre pump can do the job!) to dry it. As you strip down cylinders, calipers etc clean with whatever proprietary brake cleaner spray can. Once reassembled I would then fill the system with Dot 4 and then flush it through, as it were, by bleeding all four corners comprehensively.

 

It isn't always appreciated that Dot 4, although it has higher dry and wet boiling points than Dot 3, does tend to absorb atmospheric moisture more quickly than the earlier specification. Even for a car in occasional use I would prefer to change Dot 4 every 2 years as opposed to 3 years for Dot 3.

 

Incidentally, I experienced the incompatible Dot 4 problem with my Humber last year - the rear drum seals let go after refilling. Now replaced with modern cylinders, and I replaced the flexible hoses at the same time along with front drum and master seals.

 

Hope that helps - just my views, not gospel !

 

Cheers,

 

Alec

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wen ye say its gone cloudy,

ye mean its gon silvery and it got streaks in the fluid,!!

 

if it is, then its the ally of the unit

generally happens wen fluid is,nt changed v often,

gets water init, an attacks the ally

 

other thing is seals so worn, then other bits are rubbing ont MC

tell tale signs are shiney bits on the inner working bits

 

M

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