XC70: General Brake fluid grade query.

[Ian21401]

I’ve just been replacing front brake discs and brake pads on daughter’s XC 70.
Pushing the pistons back bled some fluid off via the bleed nipple.
Need to top up the brake master cylinder.
Cap on master cylinder states Dot4. Owner’s manual states Dot 4 plus.
I have plenty Dot 4 in the garage but no Dot4 plus.
Is it safe to top up the master cylinder with Dot 4 ?

[dingov70]

DOT3, DOT4, DOT4+ and DOT5.1 are all Glycol based. The differences are in viscosity and boiling point. Use the grade that your car calls for (Volvos are usually DOT4), with DOT4 and DOT4+ pretty much interchangeable

Hope it helps you

[Ian21401]

Originally Posted by dingov70

DOT3, DOT4, DOT4+ and DOT5.1 are all Glycol based. The differences are in viscosity and boiling point. Use the grade that your car calls for (Volvos are usually DOT4), with DOT4 and DOT4+ pretty much interchangeable

Hope it helps you

I wasn’t sure what the difference was between DOT4 and DOT4+ but you’ve confirmed what I was thinking regarding interchangeability, especially as the master cylinder cap simply states DOT4.

[Ian21401]

No DOT4+ available at my usual local stockists. Plenty DOT4 or DOT4 ESP.
I had to damage one of the “6 point flange screws” which secure the disc to the hub as it would not loosen and the torx socket quickly deformed. The head appears to be very soft.
I eventually managed to drifted it out with a sharp steel punch so I’ve ordered four replacement screws from my dealer as I suspect that I may have similar problems when I do the rear discs. Part no.is 30741279.
Parts dept. were surprised that the screws were not supplied with the brake discs which I had bought from them. The caliper bracket bolts came with the discs but no flange screws.
As I have to collect them tomorrow I will buy a small quantity of Volvo’s own brake fluid while I am there as the car probably has OE fluid in already.

[green van man]

I change brake fluid every 2 years useing dot 4 never had a problem on my xc70, disco 1 or the works sprinter which I know has dot 4 in it.

Buy volvo if you want to but if the car is more than 2 years old it's unlikely to be volvo fluid. They sell in litres to the public but I've seen factors delivering dot 4 in 5 litre jacks for workshop use at mine.

Paul.

[Ian21401]

If it were my car Paul I would probably have just used some DOT4 but car is not used by me. Although the car was bought used, it was from our dealer and to the best of our knowledge the car has been dealer serviced since new so it could possibly still have Volvo fluid in although I do take your point about factors delivering DOT4 to your dealer. These Volvos we now own are the first cars we have owned which have not had the braking system opened for some maintenance for some reason fairly frequently. Previous cars often had the braking system bled after fitting some replacement part so the fluid was changed, but on an irregular frequency.

[Ian21401]

Just collected four “six point flange screws” from dealer, (£2.05 each, plus vat) together with 250mls of Volvo brake fluid, (£4.20 plus vat). The fluid is identified as DOT4 & 5.1 with low viscosity with high wet boiling point and extremely good lubricating properties. Can to be used within two months once opened. But then off course the fluid is in the car for however long.

[dingov70]

I had to damage one of the “6 point flange screws” which secure the disc to the hub as it would not loosen and the torx socket quickly deformed. The head appears to be very soft.

Simple solution , ALWAYS use as large a drift as you can against the screw head BEFORE attempting to undo . The shock of impact breaks the rust bond or what ever else is likely to stop the screw from turning

[Ian21401]

The so called “flange screw” is actually countersunk into the disc. It doesn’t have a flange as I know them. The head is about 15mms diameter. As soon as it became apparent that it was rather tight I hammered the torx bit into it. I then used an impact driver. It was not budging.

[green van man]

Originally Posted by dingov70

I had to damage one of the “6 point flange screws” which secure the disc to the hub as it would not loosen and the torx socket quickly deformed. The head appears to be very soft.

Simple solution , ALWAYS use as large a drift as you can against the screw head BEFORE attempting to undo . The shock of impact breaks the rust bond or what ever else is likely to stop the screw from turning

My go to tool for that job is a cheap manual impact driver. Half inch drive one end big head for hitting with hammer the other.. The blow causes a turning movement as well as the thwack to break any rust. Last one I baught cost less than a fiver, comes in a neat little case with 4 screwdriver bits and a half inch drive holder.
Sure eBay or toolstation type place can supply.

Paul.