Heavy Brakes/Low Boost

[TNPhoon]

Ok, don't know which forum this should go in, so if it needs to be placed somewhere else, please move accordingly...

I am going to just give the best description I know how:

Brakes are HEAVY. Even with the Turbo/Wastegate disconnected, will not go down much or hold the truck back when revving up.

This particular truck had the wastegate/turbo disconnected because the person was trying to rectify a situation of not producing accurate boost. Believed that the wastegate needed to be adjusted, so had it off. Connected it and it is pulling some turbo (10psi on the stock gauge, blah).

Can the two be one in the same problems? Any ideas?

I searched the forums for "vacuum problem, heavy brakes, stiff brakes, etc" but couldn't find anything close to this, so if there is a previous thread, please point me in the right direction.

Thanks.

 

[gmcturbo]

Re: Heavy Brakes/Low Boost

the brake booster works off of manifold vacuum, so if there is a big leak in the hose or diaphram you will have a stiff brake pedal.

 

[TNPhoon]

Re: Heavy Brakes/Low Boost

the brake booster works off of manifold vacuum, so if there is a big leak in the hose or diaphram you will have a stiff brake pedal.

So I would assume that it could also be that a line was hooked up incorrectly or not tight enough or something to that effect also? Would that have an effect on the brakes being stiff AND the turbo only pulling 10psi, or is that more than likely completely unrelated?

 

[dgoodhue]

Re: Heavy Brakes/Low Boost

It could a vacuum boster leak. I have never heard of another SyTy with that problem, but I had that problem with my Corvette.

 

[Don W.]

Re: Heavy Brakes/Low Boost

Wastegate and vac for brakes are not related exactly. When you let up on the throttle the engine builds vac which is plumbed to the booster by the large hose connecting the two. Hard brakes can be caused by low vac and/or bad booster diaphragm. Vac leaks can be the cause of the low vac hence hard brakes so it kinda comes around that you gotta have both, good vac at idle and a good booster. Also at the diaphragm is a check valve, if that is bad whatever vac you had (building boost at the line for example) will be gone and actually work against you. I'd check or just replace that valve, they're cheap.