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wtyrrel

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Discussion starter · #1 ·
Not sure how else to describe it. First inch where you expect the brake pedal to work: it doesn't. Thereafter it feels fine. Brakes work.
Once you get used to them, they're fine.
I bought the car from a fellow swedespeeder and he chased this problem. He had them bled several times, checked calipers, replaced hoses, pads/rotors, began looking into vacuum leaks/vacuum pump.
I had my car in the shop for annual inspection, and asked my mechanic to look into it. I found another Volvo forum another guy had the same problem, and he fixed it by having the ABS bled, so I was going to have them try that.
They decided that wasn't the problem and they think it has DOT3, not DOT4 in it - that it 'feels' different. I don't go around touching brake fluid enough to comment on that.
He said he 'called Volvo' to see if that could cause it, and they (whoever he called) said yes. They did not bleed the ABS.
They think flushing the brake fluid back to DOT4 should be done - and they don't flush brakes. Apparently not many shops do. They didn't charge me anything.

Mentioned it to my dad, who talked to his mechanic/sales lot, and their knee-jerk reaction was: rear calipers are bad - replace.
The calipers remove any after-rain scale from the rotors, as expected - and rotors are smooth as the front. Rear pads have more pad than front, but they're newer, so entirely expected.
This shop has not SEEN my car.
My dad wants to pay for replacing the rear calipers for me.

I honestly don't think either is the solution to whatever this is: I'm just living with it - once you're used to them, they stop, will stop fast if pushed, and will ABS if pushed hard; no pulling that I can discern.
My post is asking you guys if you would let them replace the calipers. If you have another solution...
 
Assuming you did check all the regular things like caliper bracket springs that were installed in a wrong way, etc, etc...

ABS can be bled easily. Snap on your DiCE/VIDA, go to Diagnostics/Vehicle Communication/BCM/Activation tab and play with the inlet and outlet valves of the wheel that you are bleeding at the same time. Sucking fluid out of calipers works best in my experience. I have a more expensive Motiv bleeder, it never worked as well or as easy as my dirt cheap suction gun.

One of folks I know, who has no DiCE, did a successful air release from ABS to brake lines by triggering ABS in snow. He immediately almost lost brakes of course, but at least he was able to suck air bubbles out after that "treatment".
 
Discussion starter · #3 ·
Oh boy, so much fun had.
They replaced the master cylinder and fixed the brake pedal. Made all the wheels lock up.
They had to 'adjust' the pin (I assume it connects the master to the booster) after being towed back.
Now it feels *exactly* like it did when we started. If I had paid this shop, I think I'd be suing them; my dad seems okay about, so oh well.
I'm not dealing with that shop again.

F*ing idiots turned my A/C on full blast...why the F* can techs not f*ing use the GD auto-climate? It WORKS! It's twenty+ year old technology!
Now my vents smell like mildew. I'm not sure it's related, but oh well.
Only smells when I'm not running A/C or heat.. it's weird. (it was especially nice this week, and I was just using the fan).
Cabin filter is filthy, but does not smell; ordered a new one.
 
Maybe do an old school trick to see if there is issues with calipers or hoses. Get some small vice grips or brake hose clamps, lock off all of them at the top of each of your rubber brake hoses, try pressing the pedal, there should be no travel in the pedal, if there is travel then there is a problem further up, possibly the ABS unit, if it doesn't move then your problems are in the hoses or calipers, try moving the clamps to the bottom of the hoses, then press the pedal again, if it has little to no travel then the issue is calipers, if it travels then you have hose issues, move the clamps one at a time back up the hose rechecking the pedal travel, the clamp that you moved that stops the travel has just identified the faulty hose, if it didn't move, then release the clamps one at a time and press the pedal, the clamp you released that allowed pedal travel has just identified which caliper is at fault.
 
Booster Vacuum Switch

Check your booster vacuum switch (Volvo 30645493). There are ways to check it by depressing the pedal while turning the car off and on, do a search for the instructions. The switch is located in front of the airbox -- pls see the pic of mine below. Mine cracked (the originals were two piece, with flimsy plastic notches holding it together, the new ones are one piece) and I put it back together with epoxy and a hose clamp until I get a new one. It actually works fine now. I don't think a failed one will show up as a vacuum leak, just a weak, seemingly low brake pedal.
 
Check your booster vacuum switch (Volvo 30645493). There are ways to check it by depressing the pedal while turning the car off and on, do a search for the instructions. The switch is located in front of the airbox -- pls see the pic of mine below. Mine cracked (the originals were two piece, with flimsy plastic notches holding it together, the new ones are one piece) and I put it back together with epoxy and a hose clamp until I get a new one. It actually works fine now. I don't think a failed one will show up as a vacuum leak, just a weak, seemingly low brake pedal.
+1.

Dot3/dot4 isnt going to change pedal feel. Really no different e other than a few points of boiling temp between the 2.

Before replacing calipers, consider replacing the brake hoses first. Do you know how old they are? They could be weak and ballooning under pressure. There are stainless steel braided lines available, that would firm up the pedal a bit.

More aggressive pads/slotted rotors would help also...
 
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