08 exp spongy brake pedal

[dyablo]

so I replaced the MC bench bleed that and the whole system. Brakes grab super fast but felt like no Bk booster at highway speeds.

Replaced the booster and still no improvement. Brakes grab at say below 40mph can activate abs. But anything over that and brakes won’t kick in ABS even while slamming the brakes at 80mph.

I’ve bleed the system many times now and the pedal to even take it out of park will go all the way to the ground.

Kind of lost here as the brKe pedal won’t get hard but brakes are super touchy at low speed.

Do these ABS units need to be dealer bleed?

 

[1955moose]

Usually as long as you don't mess with the abs system during hydraulic repairs, they shouldn't have to be bled, or messed with. Couple of questions, 1, are you getting solid streams of brake fluid out of all 4 bleeders? 2, any abs light on dash lit up, 3, master cylinder new, or remanufactured? The fact that your not getting boost assist would lead me toward booster diaphragm, check valve, or hose to booster. None of these 3 items would cause sponginess. How are you bleeding brakes. Standard procedure is right rear, left rear, right front, then left front. Be careful not to run fluid low, or you'll suck in air. I also like to crack lines on master cylinder also to be sure solid fluid comes out everywhere. I don't need to tell you but with assistant pumping pedal, 3-4 full strokes of brake pedal, then hold it, crack bleeder. As last item run a scanner capable of abs testing, to be sure you don't have issues there.

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[1955moose]

Just reread your post, why did you originally change master cylinder? And what other components, and why. Did you replace any calipers? As I stated in my other post run a abs diagnostic, you might have a malfunction in one of wheel sensors or abs unit itself causing grabiness. Did the grabby brakes start after booster replacement?

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[dyablo]

Solid streams of fluid, bleed in the order and method you mentioned at least twice already.

It was a reman MC and Booster. New check valve also.

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This all started when suddenly coming to a slow casual stop the ABS would kick in for no reason. This happened a few times then no issues. The issues returned about 4 months later but started happening way more frequently and right before our out of town trip.

Replaced the MC thinking it was on its way out. Bleed that and then noticed the feeling of like no booster. Again had a trip planned so replaced that to just in case.

That’s when the super touch brakes happened after the booster. The pedal just never gets hard with the car running and it feels like there’s no brake assist.

With the car off a few pumps and the pedal is rock hard and stays that way does not loose pressure. Took booster off looking for the adjustment rod and could not find any way to adjust it.

And little pressure on the pedal and the car nose dives. But that’s about it still does not have the full brake effect.

Going to buy a vacume blended later today and try that. Running out of options aside from taking it to the dealer and getting it with no lube.

 

[JExpedition07]

A reman........ uh oh, I’ve pretty much given up on reman parts nobody does it right anymore, not even ford.

 

[1955moose]

Well the fact that your master cylinder holds with key off you can rule out it, and hoses, and calipers. You still haven't told us is their a abs light on! Does it light when you turn key to on position before starting vehicle. Do that, report back. Your issue sounds more and more like something with abs unit. Manufactures of boosters test their products and set their booster rods close to spot on of original Ford, so the chances of it over boosting are minimal. Besides it would stay touchy at all speeds, not just lower ones. Diagnose codes, and sensors in abs system, and report your findings. Moose.

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[dyablo]

Well the fact that your master cylinder holds with key off you can rule out it, and hoses, and calipers. You still haven't told us is their a abs light on! Does it light when you turn key to on position before starting vehicle. Do that, report back. Your issue sounds more and more like something with abs unit. Manufactures of boosters test their products and set their booster rods close to spot on of original Ford, so the chances of it over boosting are minimal. Besides it would stay touchy at all speeds, not just lower ones. Diagnose codes, and sensors in abs system, and report your findings. Moose.

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No ABS light or CEL on. ABS light does do it’s self check prior to ignition then turns off as normal.

 

[1955moose]

I'd still run the codes with a scanner. Did the grabby pedal start just after master/booster swap?

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[dyablo]

Ok gonna have to find someone with a scanner that can check for ABS codes.

The lack of booster went hand in hand after swapping the MC. BUt the super grabby/touchy pedal started right after the new booster.

Just got back from store picking up the vacuum bleeder. Gonna try that and report back.

 

[GaryH2]

I had a similar issue in my 07. In my case, it turned out to be a collapsed flex line to a caliper (after replacing the caliper, rotor and pads...). If you haven't checked those, it might be worth a look.

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