Hard brake pedal in reverse

[shack]

So we went for a jaunt today to a sale, had the trailer on which has override cable brakes, nothing strange happened until we are loading up our valuable purchases and I was backing down a hill.

As I was going very slow backwards down the incline I was riding the brake pedal, probably only went 25 metres and the pedal went hard as a rock and wouldn't hold the car,I grabbed drive to stop and it was fine then, the brake pedal went back to normal, so I thought I would test again....Yep the same, so on the way home I tried going downhill forwards, couldn't make it happen.
So what's going on? Vacuum leak? Vac pump on the way out?

Cheers James

[Aaron IIA]

Were you riding the brake pedal at a constant pressure, or repeated on and off?

Aaron

[justinc]

Remove the vac fitting and poke a long zip tie in as a dipstick, I would bet on the booster having oil in it, reduces its capacity by up to 40% at least....

[shack]

Were you riding the brake pedal at a constant pressure, or repeated on and off?

AaronProbably a few jabs, but then riding the pedal and went hard, but I'd have to re check for sure

[shack]

Remove the vac fitting and poke a long zip tie in as a dipstick, I would bet on the booster having oil in it, reduces its capacity by up to 40% at least....Ok I can try, but I thought they had an electric vac pump, so the "oil" would be brake fluid? So the master cylinder would be down on fluid then?

Edit: just checked, it's full to the full mark

[justinc]

Diesel or petrol? Diesel were prone to this issue only.

[shack]

Diesel or petrol? Diesel were prone to this issue only.Diesel

[shack]

But where does the oil come from?

[justinc]

Discovery 3 Brake Booster: TDV6 (https://www.4x4community.co.za/forum/showthread.php/244563-Brake-Booster-TDV6)

[PerthDisco]

Discovery 3 Brake Booster: TDV6 (https://www.4x4community.co.za/forum/showthread.php/244563-Brake-Booster-TDV6)

Does this problem disappear after a certain model year?

[shack]

So I've checked the oil level with a "dipstick", the dipstick got oil on it but very minimal, what's the next move?

[justinc]

Sick it out, tube and large syringe

[Eric SDV6SE]

Justin,

Do you know if this occurs on diesel D4’s as well? If so, can you post a pic of the vacuum hose to disconnect to check?

thanks in advance,

Eric

[Barryp]

There was a recall on diesel D3s. Its engine oil coming up from the vacuum pump. The recall changed the plumbing from the vacuum pump (back of engine driven off the camshaft) to the brake vacuum booster. Shouldn't be an issue on a D4 unless a seal has gone in the vacuum pump.
Regards Barry

[shack]

Diesel or petrol? Diesel were prone to this issue only.So I've just realised that the electric vac pump I bought months ago from a D3 wreck, was obviously a petrol, that's where my confusion started,I couldn't work out how an electric pump would let oil into the booster, of course it can't.

I think the brakes are getting harder,
I'll have to get into the job seriously this week,I found a government recall on the pump, looks like there is a sticky valve that can give problems as well.
Thanks for your advice

Cheers James

[shack]

There was a recall on diesel D3s. Its engine oil coming up from the vacuum pump. The recall changed the plumbing from the vacuum pump (back of engine driven off the camshaft) to the brake vacuum booster. Shouldn't be an issue on a D4 unless a seal has gone in the vacuum pump.
Regards BarrySo is there any evidence now that the updated plumbing between the vac pump and the booster actually fixes the problem?

I've discovered that the issue with ours isn't reduced vacuum capacity in the booster due to it being full of oil, the fault is the booster is leaking quite badly...No doubt due to oil ingression.
I'm thinking it already has the updated plumbing, but that it was fitted AFTER the current booster already had oil in it, so I'm hoping a new booster will fix the problem.

Other than that I guess I would need to also replace the vac pump if it was faulty to stop oil ingression, which I really don't want to do !
But how would I know that it was faulty?

It creates good vacuum, and there appears to be very little oil actually in the booster.

Any thoughts from anyone, I'd love to hear!