hydro boost issue

[duallydmax06]

Hello everyone, im working on a 84 gmc 1 ton crewcab dually 2wd with a 454 it has the hydro boost system on it and my problem is the other day the brake light came on and i lost power brakes the truck still stops you just have to press real hard now. The weird thing is the power steering still works great, acouple days ago i put some lucas power steering additive in for the leaky gear box that stuff slowed the leak down on my 85 so figured i try it on this one, anyone have a idea whats goin on here since the power steering still works?

[zieg85]

Those "fixes" swell rubber seals, OK for just power steering, probably not OK for the hydraboost unit...

[duallydmax06]

It acted up the same day the lucas stuff went in you think it did damage to the hydroboost that quick?

[duallydmax06]

Anyone else have any ideas???

[bd]

Make sure the master cylinder is full of fluid, check the rear drum brake adjustment and inspect the calipers, rear wheel cylinders and all brake lines for leaks.