MOT coming up. Fluid change?

[qprdude]

I have booked an MOT at Citroen in Inverness.
Mainly because if something needs doing, there is a fair chance that it would be under warranty.
I've also asked them to change the brake fluid. I'm not sure on this . Citroen service book say's it should be changed every two years.Now in 46 years of owning cars, I have NEVER had brake fluid changed, apart from maybe back in the days of Girling and Lockheed fluid, when bleeding the brakes after a shoe change, I might have managed to completely bleed out the old stuff.

Does anyone change the fluid as a matter of course, and does it make a big difference.? My brakes seem OK, but I suppose as they get softer I don't really notice too much.

[myglaren]

They will test the brake fluid for water absorption and advise that it be changed when it reaches a certain level as described by the MOT test manual.
Haven't had mine done in ages though - not with the two C5s as far as I know.

[waynedance]

I change mine every 3 years but I do work at a garage which makes it free and easier.

[RichardW]

Nothing in the MOT about checking the water content of the brake fluid....

2 problems with 'wet' fluid - 1) it can boil if you work it hard (or you've got a dragging brake), which leads to interesting moments when the pedal goes to the floor (been there, done that!) or 2) it can allegedly corrode the inside of sensitive ABS components (more likely on a modern car).

No idea whether 2 years is really appropriate on modern fluids or not - garage may have a spectroscope they can check it with. It's reportedly a money spinner for garages - suck the fluid out of the tank, stick new in, then open all the bleed screws into pots and let it gravity drain whilst you get on with the rest of the service - then charge the punter an hour's labour

[myglaren]

Hmmm.
Last car it was done on was my Accord, in for MOT and they said they had checked it and it was a fail so had flushed and refilled with new.
A very reliable testing station too.
That was about 12 years ago now though.

[RichardW]

You were had....

[qprdude]

Cheers Steve.
I've asked them to flush it anyway. I just wanted to know if I'm wasting money. I didn't know they tested it at MOT . Never heard of that before. Maybe I should just ask them to do it if it actually needs it.
The thing is, the brakes have never been as good as on my last car, but that was a 1.9 TiD Vector Sport , and a much lighter car.

Wayne, it's not being done as part of a service, just a stand alone along with an MOT.
My main concern was if the fluid had water (corrosive) or air bubbles( spongy). I don't do a massive amount of miles, but I do a few longish (1300+ miles) motorway journeys a year and I like to keep up with motorway traffic. Good brakes are a must with the current tendency to give you clearance of a few feet before cutting in front.

[Northern_Mike]

They will test the brake fluid for water absorption and advise that it be changed when it reaches a certain level as described by the MOT test manual.

There's nothing in the MOT test about water in brake fluid, and I've never had a car or motorbike tested for it in 25 years. I changed the DRK fluid about a month ago, the Berlingo was done about 6 months ago. I've got one of those ezibleed things, makes it a doddle.

[waynedance]

Yeah not part of mot test......

[qprdude]

They will test the brake fluid for water absorption and advise that it be changed when it reaches a certain level as described by the MOT test manual.

There's nothing in the MOT test about water in brake fluid, and I've never had a car or motorbike tested for it in 25 years. I changed the DRK fluid about a month ago, the Berlingo was done about 6 months ago. I've got one of those ezibleed things, makes it a doddle.

Did it make a difference?

[Northern_Mike]

They will test the brake fluid for water absorption and advise that it be changed when it reaches a certain level as described by the MOT test manual.

There's nothing in the MOT test about water in brake fluid, and I've never had a car or motorbike tested for it in 25 years. I changed the DRK fluid about a month ago, the Berlingo was done about 6 months ago. I've got one of those ezibleed things, makes it a doddle.

Did it make a difference?

Honestly?

No.

The fluid that came out was obviously slightly dirtier than that which went in but I didn't notice any difference in braking power or pedal feel.

[qprdude]

OK. That's good to know. There's so much confusing opinions out there. Some "experts" say 30,000 miles or every two years but as I've never changed brake fluid, I'm sceptical. At just under £50 for a fluid flush, I would expect at least a small difference in braking.
I never thought of it until I read the service schedule and considering the old Girling/Lockheed system was about as watertight as a sieve at the reservior, I am beginning to think of the flush as a nice little earner for garages.

[Northern_Mike]

I suppose the bits of crud suspended in the brake fluid, could in (a lot of?) time cause some scoring or damage somewhere in the system, but I'm yet to hear of old fluid causing such a thing, or total failure. The fluid in the DRK was at least 14 years old. It was a bit grubby, that's for sure, but bear in mind the braking system is from a 1978 car with drum brakes and a girling master cylinder. It still made bog all difference. New shoes made a difference, but not new fluid!

[Mandrake]

I've always thought the reasons for changing DOT4 fluid were:

1) To prevent too much build up of absorbed moisture in the fluid which will lead to vapour lock during prolonged heavy braking, (been there done that, not fun!! )

2) To replace the corrosion inhibitors that eventually wear out. (Same reason you want to change coolant)

Unless you're in a vapour lock situation the old and new fluid shouldn't "feel" any different when you brake, but you may be able to brake hard for longer (descending a hill while towing etc) without problems on the fresh moisture free fluid.

[qprdude]

I never tow anything, and I tend not to be hard on the brakes over long periods. (emergency braking happens, but very seldom). I'm usually looking well ahead and slowing down a fair bit before brakes are needed. I may just save the £50 for something more worthwhile. Any suggestions?