Rooster2 Posted May 7, 2015 Share Posted May 7, 2015 My 98 OBW has power brakes, but the "power" seems gone. Pushing on the pedal feels like standard old brakes, on cars that I have owned long ago. The brakes work just fine, just have to really press down on the pedal to stop. I am thinking the power brake booster has gone bad. I don't detect any vacuum leaks anywhere. Anyone ever have the same problem, and if so, how did you fix it?? Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted May 7, 2015 Share Posted May 7, 2015 There's a check valve built into the vacuum hose that goes to the booster that fails. Usually it freezes in the winter if moisture gets in the hose. Pull the hose off the booster with the engine running and see if you have vacuum there, if not, check at the port on the manifold. If you have vacuum at the manifold end but not at the booster end replace the hose. Last I checked that was a dealer only part for new. If there's a u-pull junkyard nearby, used is fine. 1 Quote Link to comment Share on other sites More sharing options...
Rooster2 Posted May 7, 2015 Author Share Posted May 7, 2015 There's a check valve built into the vacuum hose that goes to the booster that fails. Usually it freezes in the winter if moisture gets in the hose. Pull the hose off the booster with the engine running and see if you have vacuum there, if not, check at the port on the manifold. If you have vacuum at the manifold end but not at the booster end replace the hose. Last I checked that was a dealer only part for new. If there's a u-pull junkyard nearby, used is fine. Thanks Fairtax4me, I will follow your advise and check out the hose. Regards..............Larry (Rooster2) Quote Link to comment Share on other sites More sharing options...
Rooster2 Posted October 21, 2015 Author Share Posted October 21, 2015 Took me a while to get around to working on this. I checked the vacuum hose for vacuum, and it seemed just fine. I replaced it anyway, but found no imprvement. Brakes conntinue to work just fine, but just don't feel like power brakes. It still takes some extra effort brake pedal effort to stop the car. I replaced the brake booster, but that has not fixed the problem. The problem is on my 98 OBW. I also have a 99 OBW, so I can easily tell that the power brake function is not working well on the 98. Any suggestions..............Thanx Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted October 21, 2015 Share Posted October 21, 2015 (edited) did the car have normal feeling brakes in the past? any work done or wrecks before the problem began? inspect all the brake calipers and caliper brackets. are all the brake pads wearing evenly? any wedge-shaped? brake lines bled of air? any damage or major rust around the firewall where the MC is mounted? after idling the car, pull the hose off the booster, there should be a woosh of air go into it. If not, it could have a leak? (I don't guess it's possible the booster hose is on backwards? maybe test by blowing into it - should block blowing from the engine side) Edited October 21, 2015 by 1 Lucky Texan Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted October 21, 2015 Share Posted October 21, 2015 I would guess the booster has failed. In your other car, start the engine, release the brake, then turn the engine off. Press the brake pedal 4-5 times and you'll hear it whoosh a few times and the pedal will start to get harder to push. Do the same test on your 98 and if the pedal gets hard to push sooner, the booster is bad. Quote Link to comment Share on other sites More sharing options...
Rooster2 Posted October 21, 2015 Author Share Posted October 21, 2015 I would guess the booster has failed. In your other car, start the engine, release the brake, then turn the engine off. Press the brake pedal 4-5 times and you'll hear it whoosh a few times and the pedal will start to get harder to push. Do the same test on your 98 and if the pedal gets hard to push sooner, the booster is bad. Good advise, I will give it a try. Thanx Quote Link to comment Share on other sites More sharing options...
idosubaru Posted October 22, 2015 Share Posted October 22, 2015 You replaced the brake booster and it's still doing this? Has it always done this? What's the history - when did the issue start, any accidents, major work...? Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted October 22, 2015 Share Posted October 22, 2015 I must have misread that part. I thought just the hose was replaced. If the booster itself was replaced then there must be something else going on. Has the Master cylinder been replaced at some point in the past? Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted October 22, 2015 Share Posted October 22, 2015 a 98 in Indiana could have rusted lines - any loss of fluid or drips from the gas tank area? Quote Link to comment Share on other sites More sharing options...
Rooster2 Posted October 22, 2015 Author Share Posted October 22, 2015 A history update.........brakes have felt like manual brakes, not power brakes for some years. Last January, I had brake lines replaced at the rear, as they had rusted out. Work was done at a shop that I trust, and felt they did a good job of bleeding the brake system after installing new lines. As stated earlier, the brake booster unit was replaced about a year ago. Still, the brakes felt like manual brakes even with a new brake booster. The brake pedal feels good and solid, when brakes applied, so I don't get a sense that the master cylinder is the problem. Front pads replaced within the last 10K miles, so I think the pads are okay. Still a mystery to me. The car's brakes make the car good and driveable, and not a safety issue. Still, it would be easier having power brakes once again. Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted October 22, 2015 Share Posted October 22, 2015 I wonder what a system would feel like if there were air in the ABS pump? how is that system bled? Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted October 22, 2015 Share Posted October 22, 2015 My thinking was that if the MC has been replaced in the past, someone may have installed the wrong one. There were two different sizes that could be used. One had a 15/16" bore, the other a 1-1/16" bore. If I remember right, the Outback should have the smaller bore. Quote Link to comment Share on other sites More sharing options...
Rooster2 Posted October 22, 2015 Author Share Posted October 22, 2015 My thinking was that if the MC has been replaced in the past, someone may have installed the wrong one. There were two different sizes that could be used. One had a 15/16" bore, the other a 1-1/16" bore. If I remember right, the Outback should have the smaller bore. hmmmmmm......that is an interesting thought. We bought the car used many years ago. I can't ever remember the brakes acting like power steering brakes. You may be on to something. MCs don't cost much, I may swap it out to see it that is a fix. Thanx. Quote Link to comment Share on other sites More sharing options...
matt167 Posted October 22, 2015 Share Posted October 22, 2015 hold brake pedal with engine off. Start engine holding brake. Pedal should drop just a little. No drop, means no assist working Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted October 22, 2015 Share Posted October 22, 2015 hmmmmmm......that is an interesting thought. We bought the car used many years ago. I can't ever remember the brakes acting like power steering brakes. You may be on to something. MCs don't cost much, I may swap it out to see it that is a fix. Thanx. The size should be stamped somewhere on the side of the MC. Might check for that and see if its the correct size. If you have the factory service manual for the car, look in the brakes specifications and it should say which size MC should be on it. Quote Link to comment Share on other sites More sharing options...
johnceggleston Posted October 24, 2015 Share Posted October 24, 2015 the brakes in my 97 Gt wagoin are very different from the brakes in my (now sold) 95 L sedan. dramatically different. the 95 stopped quick and easy with less pressure. the 97 takes much more pressure and takes longer to stop. not very scientific , i know. i assume the wagon is heavier, but not 20% heavier, 10 to 15% at most would be my guess. how much of a difference can pads make? Quote Link to comment Share on other sites More sharing options...
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