Can I damage anything by...

[NJSHO]

Can I damage or otherwise royally screw up anything by bleeding the brakes with the engine running? Someone on the shotimes mailing list said his snapon scanner has instructions for bleeding the abs system. The instructions say to run the engine and open one bleeder screw then bleed normally. This is supposed to cycle the abs pump somehow. I don't know if it will work but I want to try it and I don't want to mess anything up.
Thanks

 

[Rob94]

Running the engine will cause no ill effects when bleeding the brakes. In fact, the vacuum assist makes it a lot easier. However, it requires a special scanner tool to properly bleed the ABS motor. If you are looking to bleed the COMPLETE system (abs controller and all), it is much easier to just pay a shop to do it.

 

[Shoaz]

Running the engine shouldn't hurt, but I don't really know how it will help, either. Normal bleeding works fine but leaves the little bit of fluid in the ABS pump unflushed. There is a little gadget (used to be able to get them on ebay) that will open the valves in the ABS system so that the pump is also flushed during a bleed.

Without the gadget (you can search on "Thexton ABS" or something like that on ebay) I don't know that running the engine will help, since it's not going to cycle the valves without a reason.

 

[91 SHOplus]

make sure that your supension is compressed when you bleed the brakes, otherwise the proportioning valve may not let the system be bled properly.

The 'ghetto' method to bleeding the ABS is to bleed the system, find a deserted spot to build up a head of steam and then do a panic stop hard enough for the ABS to engage. That will force the old fluid out of the ABS reservoir and fresh fluid in.

It's a helluva lot more fun than wrenching also!