Eddie Salinas

I’m flushing out the old brake fluid on my ‘92 LT1, and the service manual talks about using a special machine. I’m sure the dealers had/have it, but is there a way for us DIY’ers to successfully accomplish this task?

dizwiz24

84 4+3

With newer GM vehicles a tech 2 will do an auto bleed of the module. If you slam on the brakes on a gravel road it accomplishes the same thing. Doing a standard bleed will get the majority of it out of the abs module. I wouldn't worry.

DGXR

Agreed I would not worry about it either. If your car has severely neglected history and fluid changes rarely done, then you could bleed the system and then create conditions to activate the ABS system as 84 4+3 said.

aklim

I'd check with the dealer first. Not everyone wants to work on these old cars. Too many things can break and too hard to get replacements and/or they are not familiar with it and can't make money doing that job so they might just say "Oh, we no longer have that tool." or quote you something ridiculous to get rid of you. Another thing is you could get the "specialist" to work on your car. He is the guy that drew short straw to work on old things for the reasons stated above.

If you have air in the system, I'd definitely look into getting them to purge it. That or it might take a while to get the thing purged triggering the ABS.

DUB

So much of this depends on your interpretation of 'flushing out the brake system'.

I have a pressure bleeder that attaches to the master cylinder so I can force fluid through the system under pressure...about 22 psi if I am not mistaken.

As for using any type of cleaner. IF that is what you feel that 'flushing' means. I would not. You are asking for potential problems due to breaking up some crud that can get into your ABS unit and then causing for it to fail.

Just bleed out the system and move on and try not to reinvent the wheel here. OR...reinvent the wheel...it is up to you. Because if you were in my shop and said you wanted me to flush out the brake system with cleaner ..I would hand your keys back to you and wish you a good day. I am not going to be held liable for doing a repair that I know can come back and haunt me....especially when I am dealing with the brakes.

DUB

aklim

Hey, Bill Does it depend on what "is" means too? Lol.

OP. Seriously I would buy that and did. You can hand pump or get the shop air one. If you get the adapters you can do it for all your cars. MB suggested 2 years and I do that for 3 MBs, 1 Ford Excursion and 1 C4. At the very least. Attached to reservoir, pump and open bleeding screws.

I would not either unless I don't like the guy

I wouldn't risk it on my own business either.

confab

Agree.. I got the hand pump MitiVac version and it works GREAT for brakes and hydraulic clutches.

Only "flush" with clean brake fluid, imo.. There's no need to put a "cleaner" of any type in there.

Kevova

Never heard of a cleaning fluid for brake hydraulic system. Most of the time it is a vacuum bleeder and 2 quarts of DOT 3 or 4. Do not use DOT5. GM does have a pressure bleeder more trouble than it's worth. Letting master cylinder drain out of fluid is trouble. It is easy for air bubbles to get trapped in module. It does have bleeder screws. It still take several abs stops to cycle air out. I prefer rain soaked empty parking lots to panic brake for abs cycling. Afterwards you want to bleed brakes one more time.

aklim

​​​​​​. Maybe not but when you get a rube in front of you and you are a crook, the possibilities are endless