I heard it on a forum, therefore it must be true

[TooManyHobbies]

I have read a few things recently here and there that has caused me to scratch my head and wonder. These things go against my engineering knowledge and I currently think they are hogwash:

1. Do not move the blade by hand when cleaning a throttle body. Granted it you were cleaning the throttle body with the car running this would be a very bad idea. Most people remove the throttle body to clean it. I believe that if the TB is removed and disconnected from power, no ill effects will come from moving the blade a bit to clean it. It is just a servo motor driven flap with a return spring. If there is no power to the system it could care less what the flap is doing.

2. Do not push brake fluid backwards in the system because you will damage the ABS valves. This is when you are replacing pads and use a clamp. ABS valves have three positions, open, only allow flow towards the brake, only allow flow away from the brake. The default position should be the open position because this is what you use during normal operation. This would also be the position if the ABS system failed since you would still want the brakes to work. This should also be the position the valves are in if the car is off when you are fixing the brakes. An open valve does not care about fluid flowing through it. The kernel of truth to this is that it could bring debris back up into the valves from the lines. I have difficulty believing that pushing fluid out of one cylinder for maybe a 1/4 inch will displace fluid from the piston all the way back to the valves. If you have that much debris in the lines closer to the valves the car has bigger issues.

Anybody have anything to refute these?

Anybody have anything else to add to the list that they are wondering if there was really anything to?

[Eidolon]

I've never heard of point 2 in my travels across the Intertubes. If it were true, the recommendation everywhere when replacing your brake pads would be to crack the bleeder on your brake calipers when pushing the pistons back into place, lest you backfeed fluid into the reservoir. So I feel OK calling bunk on that one. There are bleeder systems that push fluid through the caliper into the reservoir, though, and those are to avoided for the reason you state: any dirt or debris in the caliper gets cycled back into the ABS module and master.

On point 1, I know I've pushed the blade on my throttle body around before while the car was off, to no ill effect. Definitely don't do it quickly, but other than that...

Really, these are just my opinion, more or less lining up with your feelings that both these are untrue or at least over-cautious.

[Chewy]

As Kevin alluded to. I think you're OK with the TB as long as the power is OFF! DO NOT try to push it open when it's on though. Never heard the brake issue. I've done brakes on several ABS cars and NEVER had an issue with ABS afterwards.

Chris

[Kermit]

1. How do you think people that port the TB do it without opening the butterfly? I see no problems with moving the blade with no power connected.

2. I have always used a C-clamp to push the piston back in with no ill effects.

Hogwash on both I say!! :)

[BuildItYourSelf]

Every one knows you can't run fluid back through the abs.
I mean its common knowledge the fluid leaks out when you let off the pedal. That's why there's a fluid reservoir And a add line.
Jeez some peoples children.

I will say I most always crack the bleeder and push the pads back. Its easy and puts fresher fluid in the piston bores. But not because of the abs damage. That's just stupid.