I love my 99 S70 T5. I have been enjoying the ride since I got it last month. I almost forgot about my new Accord V6. However, there are so many problems. More than enough to keep me busy over the entire year. So, worrying about my Volvo became my new hobby, which is a reasonable start considering that I was the kind of guy who never opens the hood until I got Volvo. The previous owner did as little maintenance as possible. I intend to spend all my weekends and some money to revive this one. So, here is one thing I am on.

My brake works but it requires more force than any other car that I drove. Pedal goes low when it starts applying brakes. Until then, it feels like sponge. My mechanic replaced front rotors and pads. It was better but still not good enough. I did some research and read that malfunctioning ABS module would contribute to it. So, I took care of the ABS module soldering problem. It was better again, but still not good enough. A couple of days ago, I had my brake fluid flushed. It was slightly better but pedal still feels low. I have been observing the fluid level for a month, and it has not changed. So, I guess there is no leak. I also tried the three diagnostic tests given at http://www.google.com/url?sa=t&sourc..._YmabRTz77dEtQ
My Volvo passed the first two tests but failed at the last one, which suggests that vaccum is fine but booster is bad. I don't know if Volvo works differently but if replacing the booster, which I assume will costs a lot, is my only option, I would just ignore the issue and move on to the next. If there are other possibilities or some tests to find or rule out the cases, let me know. Oh, another thing to note is to keep the car stopped at stop light, i have to press the pedal hard. I don't have much knowledge about how idling works but is it possible that ETM throttle plate does not completely close and the position sensor recognize it as no idle, and the car trying to pull forward with all its torque?

 

I did not read all the way through that but I will... your mechanic, did he use Volvo parts?

 

He said he only use OEM part which he said was Brembo. I could at least see the Volvo logo on the pad, but how can I see if the rotors are OEM?

 

Usually it is hard to see on the pad without taking it off... but the rotor, if you look through the wheel or take it off, it will be right there on the front of the rotor near the lugs, there will be a spec. and should say Volvo I believe, but look for a minimum spec number, if no numbers...??? oh, i read all your thread, i just did not read through the attachment all the way just in case you thought i was rude.

 

Your symptoms certainly suggest a bad brake booster. You said your's failed test #3; did the brake pedal go down or come up after 30 secs? Have you ruled out seized/frozen calipers?

Here's a simple test; find a non-busy side street with an incline; point the car downhill; from a stop with engine off (key in ACC position so you can steer of course..), gear in neutral, let the car start to roll down the hill. Without starting the engine, note the brake pedal pressure required to slow the car. Now start the engine but leave in neutral; do you now need same brake pedal pressure to slow the car? If so, booster is bad.

These cars have pretty incredible stopping power; better than most cars I've driven; again sounds like your booster is bad. Would not be too expensive if you could do it yourself; tech did a writeup for V70 here; imagine S70 is same or similar. Also if it were me, I would replace the ck valve first just to rule that out for sure.

 

My brake pedal comes up after 30 sec. Frozen caliper... I don't know how to check it. So, can I just ask someone to press pedal while I am looking at the caliper to see if it does not squeeze?
So if it isn't from the fake rotor which i guess i cannot verify until I get a torque wrench, then it is the booster. To make sure I will try your test, but probably gonna have to find some place and right time. Maybe very early in the morning on Sunday. Can you also tell me where is this Check value? I am very nub here. Is it on the other side of the booster which I cannot see just by open up the hood?

 

I re-read your original post. You had your mech do the the front brakes; I would think he would have checked for frozen calipers at that time. I am a little perplexed why he didn't diagnose the brake booster issue too while he was in there; would think he would want to sell the work.

Would suggest you get a 2nd opinion from a qualified volvo tech; try to find a good indy shop in your area. I am a bit hesitant to suggest you change out your own booster since you farmed out the other brake work; brake work is not rocket science but it is safety critical; you really need to know what you're doing!

The check valve is that 90 degree piece of plastic that plugs into the booster on engine side; the booster vac hose fits onto it and runs to the intake manifold.
http://www.ipdusa.com/Volvo-S70V70-1...-128-361-4411/

BTW: Does your engine idle normally; at about 800-900 rpm?

 

Thanks for the info. I will check that check valve when I get home. I away for vacation now and still think about my volvo. Yes, mine idle ok I think. At least its RPM is pretty stable around 800-900, and I do not feel much vibration when I grab steering. However, I hear some vibration. I am just wondering how I do not get the vibration on my hand that I hear.