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Brake fluid contamination

I bought a 2001 Bentley Arnage with 26k miles on it six months ago and have driven it 1,400 trouble free miles since. No service records came with the car. A recent routine checkup at the local Bentley dealer uncovered brake fluid contamination. Apparently a past owner had topped off the brake fluid reservoir with mineral oil based hydraulic fluid. The dealer is recommending I replace the entire braking system for $15,000. Since the brakes work great and have done so for six months of daily driving, isn’t it possible that this particular contamination has not fatally injured the brake system and a complete flushing would be adequate?

Sounds like someone needs a boat payment paid. Although, it is a Bentley. Think Mercedes-Benz times 10. I’d try just a brake fluid exchange if no other obvious issues are in play. And do it again in 6 months just to be sure.

whatever you decide, I would seek a lower price for the job. something smells fishy here. I have no clue how Bentleys brake or what systems they use, so I won t offer any other opinions other than to say my BS detector is flashing its second opinion code

For 15 grand get the fluid flushed and offer thanks to the automotive gods if there are no problems.

Didn’t we just have this same question on another car, with oil in the brake system? There, several folks said something to the effect ‘any mineral oil will ruin the rubber parts in a brake system’, which sounds pretty much like what the dealer is telling the OP. A flush won’t do.

And there is just about nobody else to go to for this work. This Bentley is pretty much the same as a Rolls, which are infamous for super expensive maintenance. Thousands just for a regular brake job (honest). So $15k for this sounds about right.

This is why those cars are so cheap to buy - nobody wants to pay for the service.

The diagnosis sounds questionable. Contaminated brake fluid will cause the master cylinder reservoir gasket to swell and become as porous as a bath sponge. If the reservoir cap’s rubber gasket is not showing indications of cantamination I would strongly suggest finding another shop. Regardless of the brand it’s still just an automobile and anyone familiar with British brands should be able to repair whatever goes wrong. Ask around.

Perhaps Bentley uses oil-resistant materials (nitrile rubber or Viton) in the braking system.

I doubt topping it off was enough o ruin the whole system, maybe to master cylinder. Maybe! It would not have made it any further than the amount the mc could compress the fluid and then return back to the resevoir. Flush the system and go on. I doubt the dealer will bo it. They are going to say they can’t due to liability. Take it somewhere that works on Brit cars.

I looked up compatible fluid and it’s DOT4 fluid for temps up to 600 deg. Flush and replace with dot 4.

I think the advice the Bentley dealer shop gave you is the safest for you to follow. If your brakes fail, you and other drivers on the same road could be at major risk. After all, the dealer shop mechanics are the experts on this car.

Still, there’s no harm done in asking other qualified mechanics with expertise on specialty cars for their opinion. One idea, ask them if one option might be to remove all the brake parts from the car, put them on the work bench, disassemble everything – master cylinder, brake lines, calipers – clean everything with an appropriate brake cleaning fluid – then thoroughly inspect the rubber and plastic parts (seals, etc) with a magnifying glass or a lab microscope for signs of unusual deterioration. If it passes inspection ok, then just put everything back together, replace any rubber brake lines with new, and you are back on the road. That would cost less than $15K I expect.

Pouring the wrong fluid in the various componenents under a car hood is somewhat common and my experience has been that once the reservoir seal is swelled the master cylinder is beyond saving as is the ABS system if there is one. And if the system isn’t thoroughly flushed in time all the rubber componenents will fail including the hoses at the wheels. Even if the master cylinder is replaced before it fails all rubber that comes in contact with the petroleum product will soon fail.

At one time Rolls Royce and Bentley were the same car with different hoods. They didn’t start out that way and they are no longer related. One is owned by BMW and uses a BMW 7 series engine, the other is owned by VW.

That is all true, oldtimer, but the particular Bentley model that the OP owns is essentially the same in a mechanical sense as a Rolls of the same era. The only significant difference is that the Rolls of that era used a BMW V-12, and the Bentley Arnage used a BMW V-8 with twin turbos.

Nowadays, the two makes are decidedly different, and while the Rolls uses the engines, transmissions, and chassis components of its parent–BMW, Bentley now uses an engine that is a highly-modified VW W8 engine.

Yup! Buy a new Bentley and get a VW engine!