| Author | Message | ||
     David (Dave) Member Username: Dave Post Number: 51 Registered: 02-2003 |
Hi All, I'm about to bleed the brakes on my 97 Disco since after sitting for a couple for months. The brake pedal has excessive travel and feels "spongy" after depressing half way down. One method is in the Haynes manual and the other is in the LR workshop manual for the 97. Basically the difference between the two are this: 1. Haynes says (while engine is off), person #1 should depress the brake pedal as far as possible, then while holding pedal in this depressed position, person #2 open the bleed screw...then person #1 presses the pedal as far down to the floor as possible, hold pedal in this extended "down" position while person #2 bleeds the brake into a clean jar (via a tube), closes the bleed screw and person #1 lets go of the brake pedal. Repeat entire proceedure as neccessary on this wheel to get all the air out and then go onto the next wheel. There is "No" pumping of the brake pedal continously "up and down" while bleeding in this Haynes described proceedure. 2. The workshop manual differs in that person #1 presses the brake pedal down (while engine is off) and while holding it in this position, person #2 opens and bleeds brakes into a jar while person #1 pumps the brake pedal up and down continuously until no air is seen, then holds the pedal down while the brake screw is tigtened and go on to the next wheel. Two questions: 1. Which of the two methods (although similar) is prefered. 2. I noticed a small blue colored rubber piece which is the bleed screw dust cap. I tried removing it but felt it was going to tear. Any ideas how to remove this rubber dust cap in one piece? Thanks for any help you can provide! | ||
| Brian Dickens (Bri) Senior Member Username: Bri Post Number: 363 Registered: 08-2002 |
If I were going to do this I would follow the LR service manual no doubt. I used a power bleeder so that it was simple even with one person. | ||
| David (Dave) Member Username: Dave Post Number: 52 Registered: 02-2003 |
Hi Brian, Thanks for the response. I don't have a power bleeder but I do have another person who can help. I was leary of the workshop manual since pumping the break pedal while bleeding might introduce air into the system. Any idea about removing those rubber dust caps without tearing them? | ||
| Kevin Fedyk (Kovert) New Member Username: Kovert Post Number: 19 Registered: 05-2003 |
When I bled the brakes on my 325i, I did it basically the the LR manual way. I did pump the brakes but you have to remember that you need to do it in certain order. Do it from the farthest to the nearest to the master cylinder. For example, in my 325i it was passenger rear, driver rear, passenger front, driver front. With the pumping of the brake you would think you could introduce air into the system, but when you depress and the fluid is filling the jar, that's when the bleed valve is tightened again so it should not be a problem. | ||
| Alex Schubow (Alex) New Member Username: Alex Post Number: 31 Registered: 02-2002 |
Its safe to pump the brakes with the bleed screw open as long as the end of the hose connected to the bleed screw is submerged in brake fluid. If it is in the open, you can introduce air into the system. As for the dust caps, just pull them off with needlenose pliers. They may tear, but that's life. | ||
| Kevin Fedyk (Kovert) New Member Username: Kovert Post Number: 24 Registered: 05-2003 |
Yep forgot to mention that. The other thing I was told to do basically was use a turkey baster and get out as much fluid from the cylinder as possible, then top of with new fluid, and basically on the first brake you bled, keep doing it until the new fluid (change color to make it easier) is what is coming out. Might as well flush it while your doing it. | ||
| Eric Ratermann (Ericrat) Member Username: Ericrat Post Number: 47 Registered: 08-2002 |
I think you will find that when you open the bleed screw the pushers foot will move rapidly to the floor. You have to push pretty hard with the engine off. It is probably better to let that happen than to try to hold a particular position. | ||
| M. K. Watson (Lrover94) Senior Member Username: Lrover94 Post Number: 773 Registered: 02-2002 |
you could just open the resivour and then the bleeder and let gravity do its thing. a bit slower but alot easier, just make sure that you keep putting fluid in the resivour so that the bottom is not exposed. this would allow air to circulate into the system and that would be bad. mike w | ||
| Brian Dickens (Bri) Senior Member Username: Bri Post Number: 368 Registered: 08-2002 |
The power bleeder will take only a couple of days to get to you and will save you much headache (at the cost of $45 USD). This is precisely why I got one. Then you never need anyone around again. Order should be farthest from master cylinder to closest as previously mentioned. Having the power bleeder virtually eliminates the possibility of introducing air into the system and also keep in mind that if you do submerge the drain tube in the drain pan fluid, you have eliminated the possibility of introducing air into the system, but you have also increased the probibility of introducing dirty fluid back into the system. IMHO the power bleeder virtually eliminates these possibilities. | ||
| Brian Dickens (Bri) Senior Member Username: Bri Post Number: 369 Registered: 08-2002 |
Oh yes, one more thing. I toasted an old honda following a Haynes manual, so I trust them about as far as I can throw my rover. It said remove a bolt and the service manual that I did not have said loosen DO NO REMOVE. Well, that bolt was a timing belt tensioner and I was too novice to know any difference. | ||
| Peter Matusov (Pmatusov) Senior Member Username: Pmatusov Post Number: 743 Registered: 09-2002 |
one thing to consider: as you use your brakes a million times or so, the seals in the master cylinder only go so far, and wear out the MC's bore. Past that point, there's a little ridge. when you do the regular brake bleed like Dave read from Haynes (paying attention to what Alex Schubow said), you will use up all the travel of the plunger in the MC. There's a good chance of tearing the seal, and eventually having to rebuild or replace the MC. I have been there with a number of vehicles. There are two alternatives - either to bleed the brakes regularly, which nobody does, or use power bleeder and face a possibility of screwing the ABS somewhat. peter | ||
| Neil Flanagan (Electriceel) Member Username: Electriceel Post Number: 107 Registered: 02-2002 |
"or use power bleeder and face a possibility of screwing the ABS somewhat." ??? What would 10 to 15psi do to the ABS? I think manual even says do not exceed 60psi with a pressure bleeder. | ||
| David (Dave) Member Username: Dave Post Number: 53 Registered: 02-2003 |
Hi, Thanks to everyone for all your very helpful comments and suggestions. I plan to do the bleed this weekend if the weather clears up. I have 2 more questions... On my 97 Disco (U.S. model) 1. I'm trying to determine the order of bleed...lets see, 1) rear passenger, 2)rear drivers side, 3) front passenger then 4) front drivers side. Do I have the order correct??? . 2. Also since the brakes bedal has more travel than usual and feels spongy (after sitting for a month or so), is it more likely to just need a bleed or something happened to master cylinder seal (or the unit itself)? Thanks! | ||
| Brian Dickens (Bri) Senior Member Username: Bri Post Number: 373 Registered: 08-2002 |
In the service manual I believe that it even mentions that a power bleeder can be used and if so to follow the instructions on the bleeder. Would still be interested in the theory on screwing the ABS though. | ||
| David (Dave) Member Username: Dave Post Number: 54 Registered: 02-2003 |
Hmmm, I didn't see the order in which to bleed the brakes, so I'll have to look again. As for why after letting the Disco (97) sit for a month) the brake pedal is spongy and has considerably more brake pedal travel I can't figure. Just hope it is air in the system (somehow) nad not the Master Cylinder. | ||
| Neil Flanagan (Electriceel) Member Username: Electriceel Post Number: 108 Registered: 02-2002 |
"Just hope it is air in the system (somehow) nad not the Master Cylinder." The brake master is an easy swap. Don't let it intimidate you. Is the pedal ALWAYS spongy or just on the first pump? Another simple thing you can check is the one way valve on the servo. Air should only be able to be drawn OUT of it. If you can blow air through in both directions it is on its way out. A new one way valve is cheap and if you feel ambitious you can rebuild the servo for less than 40 bucks. Also, I could never get a straight answer as to why, but some people have recommended lifting the front of the truck and bleeding. I think even the dealerships do this when bleeding on the Testbook. I'm really interested in the pressure bleeder screwing the ABS theory too. Anyone have a diagram of the inside of the Wabco ABS unit? I assume its only a pump and 4 actuators controling which channel needs assistance. | ||
| David (Dave) Member Username: Dave Post Number: 55 Registered: 02-2003 |
Hi Neil, The brake pedal now always feels spongy (on every press of the brake pedal). Pumping the pedal doesn't build up any additonal pressure or lessen brake travel. Does it still sound like air may have gotten into the system or the Master Cylinder or hard to tell at this point? Not sure where the servo is but I'll have a look in the workshop manual. Sorry to "cover up" you questions regarding the pressure bleeder screwing up the ABS. Would be intereted in learning how that might be. Thanks! | ||
| Peter Matusov (Pmatusov) Senior Member Username: Pmatusov Post Number: 750 Registered: 09-2002 |
no theory known to me. i heard it from two independent sources that i tend to trust. lifting the axle while bleeding has good reason to it. It will cause the bubble trapped somewhere in the line to move up towards the end of the line - not always the flow of fluid drives small bubbles out. I've used that on the rear brakes on the rangie - maybe that, or just another bleed, did the trick. peter | ||
| Neil Flanagan (Electriceel) Member Username: Electriceel Post Number: 110 Registered: 02-2002 |
 The servo(figure 5) is between the brake master and the firewall(the round black thing). There is a line running from the plennum to the servo. Where it attaches to the servo is a valve(figure 6). This valve only allows you to draw air OUT. If you dont mind eating dirt and 10w30, remove the line from the plennum and try to blow air through the line. If you can, the valve is fucked. This seems the logical place to start(and the cheapest) as its not uncommon for this to fail and given your description, even with air in the line you should be able to build up pressure by pumping. Still get the braked blead to make sure there is no air. | ||
| Neil Flanagan (Electriceel) Member Username: Electriceel Post Number: 111 Registered: 02-2002 |
Actually that pic is not accurate. Standing at the drivers side fender, the "Non Return Valve" is on the opposite side of the servo(at 10:00 if you are facing the servo). | ||
| David (Dave) Member Username: Dave Post Number: 56 Registered: 02-2003 |
Hi Neil, No, I don't mind eating dirt and oil at all...if it means saving some money and getting to the heart of the problem. I'll try just that (blowing through the line). I guess by trying ( won't cause more air into the system? Thanks for the diagram..that truly helps. After trying this is if I find that I can't blow air "into it", then I guess my next step would be to bleed the brakes (before I tackle the master cylinder). Does anyone have any suggestions as to the order I should bleed each brakes (wheel)? (U.S. model). | ||
| Neil Flanagan (Electriceel) Member Username: Electriceel Post Number: 112 Registered: 02-2002 |
Honestly, I really don't understand how the servo actually works aside from vacuum assisting the hydraulic system so I cant tell you what type of interaction it has with the brake fluid, but I wouldn't worry about it. The servo is not filled with brake fluid if that is what you are concerned about. As far as order there are a few schools of thought. (Drivers side - D, Passengers side - P, Front - F, Rear - R) The LR manual way: front drivers side first(closest to master to farthest from master), pumping the pedal toremove air bubbles. 1. DF 2. PF 3. DR 4. PR The most common way: farthest form the master first. 1. PR 2. DR 3. PF 4. DF The voodoo way: farthest from the master to the closest, then closest to farthest, then dance naked in your garage around chicken bones. I do it from farthest to nearest. I don't think it really matters. | ||
| Peter Matusov (Pmatusov) Senior Member Username: Pmatusov Post Number: 752 Registered: 09-2002 |
If you have brake fluid in the vacuum booster, your MC is hosed. Whatever you do with vacuum lines should have no effect on air or no air in the brake lines. peter | ||
| David (Dave) Member Username: Dave Post Number: 57 Registered: 02-2003 |
Thanks Neil & Peter. It's beginning to make more sense to me! This may be a silly question but when I try blowing through the line as Neil suggested to see if I can blow air through valve, I assume the Disco engine is completely off and keyt removed from the ignition???? Is this correct or do I try blowing through the line with the engine on???? | ||
| David (Dave) Member Username: Dave Post Number: 60 Registered: 02-2003 |
Hi, Just trying to bump up this message to see if I can get additonal responses to my question (just above). Specifically.... 1. As kindly suggested by Neil (above), I will try blowing through the hose connected to the servo( a one way valve) to see if I can push air through it. Do I try this with the engine "on" or "off" (with the key removed from the ignition)??? I want to perform this step correctly. 2. With engine "on" the brake pedal has quite a bit of excessive travel and is spongy on every "push". Repeated pumping of the pedal (with engine "on") does "NOT" result in pressure being built up in the brake pedal. Does this sound more like air in the brake line (system) or problems with either the servo valve or master cylider (or hard to tell)?? Thanks again for all the help! | ||
| Peter Matusov (Pmatusov) Senior Member Username: Pmatusov Post Number: 756 Registered: 09-2002 |
David, 1. you do it with the engine off. if you disconnect the line with the engine is on, you will create a pretty big vacuum leak; there's nothing bad about it, except for the ECU may bitch about it and trip the CEL> 2. "Spongy" brake feeling - was it always like this, or after something happened? peter | ||
| David (Dave) Member Username: Dave Post Number: 61 Registered: 02-2003 |
Thanks for the info Peter. I'll definitely keep the engine "off". As for the spongy feel, I don't recall it being that way prior to having to let the DIsco sit untouched or unstarted for close to 2 months during the winter. When I finially started and drove it, the brake pedal had excessive travle and the pedal was spongy at that point. Based on this does it sound like aitr got into the system or the servo value or Master cylinder? | ||
| Brian Dickens (Bri) Senior Member Username: Bri Post Number: 380 Registered: 08-2002 |
Hey Dave, its been a week now you could have easily got that power bleeder by now and you wouldn't even be discussing wll the brake pedal pumping issues. ;-) | ||
| David (Dave) Member Username: Dave Post Number: 62 Registered: 02-2003 |
Hi Brian, I know, I know  . Actually I have been out of town much of this time (without the Rover), so I am preparing the background info on how to do to "right" until my return. All the info everyone posted has been extremely helpful and has made me more comfortable in tracking down the problem...based on what I wrote above. Thanks again! | ||
| Gary Sherman (Sbts1) New Member Username: Sbts1 Post Number: 15 Registered: 03-2003 |
Dave, it may be a little late, but I just had the same problem. When I checked the plastic check valve on the servo, I found that plastic nipple was disintegrating on nipple where the plenum hose attached. Brake pedal pressure returned to normal after vacuum was restored. Note: If this is the problem, be careful not to push the replacement grommet into the servo. |
