Leak Under Dash?

[bd1028]

I was replacing the steering shaft on my 02 silverado 2500 hd Duramax today and noticed a slight leak under the dash around the brake rod where it comes thru the firewall .What do I need to fix? New hydroboost?Master cylinder ? or Both?

Thanks in advance
Brian

[DmaxMaverick]

It's the hydroboost unit. NOT the master cylinder, unless you have an external leak that's somehow running back to the firewall and leaking in. The two don't share fluid or seals.

If the hydroboost works well/normal otherwise, you can try a service with some tranny conditioner. Perform a fluid service, and add a few oz. of Trans-Medic (what I use, or other popular "sealing" additive). Use synthetic ATF, NOT power steering fluid. This will usually seal it, and improve brake and steering performance. Stuff a shop towel under the carpet below the brake rod until it stops leaking (check/replace it often).

If it doesn't stop leaking within a reasonable period (a few hundred miles or so), the HB unit needs to be replaced.

To trade out the fluid, disconnect the return line from the hydroboost (spring clamp line at the top, not the nut fittings), and install a length of hose that can be routed away and into a container (secure the hose ends!). If you are doing it solo, place it so you can see it from the driver seat. Idle engine until the pump makes a little noise (picks up air), while slowly pumping the brakes and cycling the steering, lock to lock (it helps if the front wheels are off the ground). Stop engine, fill reservoir and repeat. Do this until the fluid coming out looks like the fluid going in. Add the ATF additive AFTER the last cycle, then top off with the ATF. Restore the return line. Idle the engine while cycling the steering and pumping the brakes, then top off as necessary. The air will find its way out.

[bd1028]

Thanks Dmax will do tomorrow.

[More Power]

As an FYI... The hydroboost unit is pretty spendy. The last I paid some years ago was around $500. Beware of cheap imports and cheap rebuilds. I bought a new GM unit the last time I needed one because of the unknowns and bad stories out there.

Jim

[DmaxMaverick]

As an FYI... The hydroboost unit is pretty spendy. The last I paid some years ago was around $500. Beware of cheap imports and cheap rebuilds. I bought a new GM unit the last time I needed one because of the unknowns and bad stories out there.

Jim

Good advice, and I agree. Lots of junk out there, and it's been that way for a long time. If it comes to that, shop around for the genuine article.

[bd1028]

fluid change out complete will put some miles on it and see.thanks for the help guys!!
very much appreciated.Now to find a steering wheel for replacement.the 403000 miles have taken its toll.

Brian