Originally posted in Brakes and Suspension but didn't get any replies there.
Short Story:
I'm not getting any braking force on my right front. All other corners are fine. When I open up the bleed valve on the caliper and press the brake pedal, no fluid comes out. I disconnected the brake line and fluid poured out of the caliper and line, but I little to no fluid out of the hard line. I was able to suction a bit out of the hard line. The ABS light on the dash comes on when the car is turned on, but then goes off after 2 sec as expected.

How is it possible I'm not getting fluid from the right front hard line when all the other corners are working fine? The situation gets even weirder considering the long story.

Long Story:
The S2000 began pulling left under braking. Checking the rotor temps indicated no braking force on the right front. I suspected a stuck piston and checked the caliper. The boot on the piston was cooked and half gone. I considered a rebuild, but calipers are cheap and just replaced both front calipers (the left was cooked too). Bleeding the left front went fine. Bleeding the right front was a little weird. At first pressure on the brake pedal resulted in a firm pedal and no air/fluid at the bleed valve. But then it started bleeding normally and I didn't think any more of it. Everything went back together and the brakes worked fine. Then a few weeks later it began pulling left again on braking. See short story.

The only think I can imagine is an obstruction in the hard line due to a blockage or the line being damaged. But line damage wouldn't fail, then work, then fail. Also, the line appears fine to the extent I can get to it, and nothing occurred that would damage it. No idea how something could get in the line and cause a blockage. Could it be something in the ABS unit? Thinking my next move is disconnect the hard line at the ABS unit and see if fluid flows freely out the other end of the line. That would probably require a full bleed of all 4 corners and may not tell me anything.

Suggestions? I'm stumped.
- Michael

 

My guess:

Fluid flows (dribbles?) out of the line when disconnected at the wheel but does fluid get into the line?

There are four (4) brake lines coming out of the ABS modulator unit. These are laid out logically with the two outer lines controlling the front brakes on their side of the car and the middles controlling the rears. Disconnect the Right Front line and depress the brake pedal. Yeah it can make a mess if fluid comes out so maybe do this with a helper and just press slowly and lightly. Ignition OFF.

Fluid comes out: Blockage in the brake line.
No fluid comes out: Problem in the ABS modulator unit.

-- Chuck

 

Thanks Chuck. Yeah, that's what I expected. Still seems weird. Good to have a second opinion and confirm I'm not overlooking something obvious. I'll let you know what happens.

- Michael

 

Yeah there are only two lines feeding the ABS module so you have already ruled those out since the other front brake is working. I would first try testing each section of line with air. Using the pedal there are pressures involved and it is easy to get fluid all over and it destroys paint. In any case have a bucket of warm soapy water available to dump onto any paint fluid may get on after to wash it off before it damages anything. But, disconnect soft line from caliper, disconnect at ABS module and use a rubber tipped air gun if possible (will seal better) to see if you can move air/fluid easily through the line. If not, disconnect soft line from hard line and try again, if still not able to you have a restriction in the hard line. If all is free, then you can look back at the module itself. I would hope if the module cannot push fluid to one corner it would trigger an ABS code but it does not sound like it is.

As a heads up, a new ABS module is about $1,500 last I checked. They do not fail often so if yours is bad, I highly recommend doing what I did when mine failed and going through A-Solutions auto parts (find them on FB). They are a salvage that focuses on cars like S2ks, Evos, etc. I was back on the track for about $100 on mine using them

 

So I disconnected the hard line at the ABS module. After a min or two brake fluid drained out the line, ruling out a blockage in the line. Pressing the brake pedal resulted in very little fluid coming up from the right front line connection. For comparison I disconnected the left front, pressed the brake and fluid surged up. So I guess I'm replacing the ABS module. I'll check out A-Solutions auto parts. Thanks for the reference, engifineer.

 

Thanks for reporting back and confirming the issue. Let us know if the ABS module replacement fixes the issue.

 

eBay seems to have inexpensive ABS modules.

-- Chuck

 

I bought an eBay ABS module and replaced the existing one. That solved the right front braking issue, but now I have an ABS light on and no ABS. <sigh> I'll try to pull the ABS code. Really don't want to replace that again. Wrestling the new unit into position and getting the 6 hard lines to thread was a pain in the ass.

 

And a much higher risk of getting a non working one and no support from the seller than using A-Solutions. I bought mine from A-Solutions for $95 shipped to my door (2 day shipping even) and had it not worked, he would have replaced it for sure. Some rando on ebay? Who knows. A-Solutions is a solid business which is why I recommended them.

 

Do you have the info on pulling the codes using a jumper in the OBD2 port? Cannot pull them with a standard OBD2 reader. If you do not know how we can help. If you do, post up the codes it flashes out and we can help guide. I actually posted scans of the shop manual pages around here somewhere I think but can do it again if you need.