Ok so here is a quick rundown of what has happened so far.
Went through the trouble shooting guide and found that I had a bad pressure switch i replaced the switch while I had the motor out. Sometime while either pulling the motor or putting the motor back into the car the rubber line from the resivior came disconnected and emptied the res. Well I wasn't even thinking about the brakes when I was trying to get the motor running. Now that I have the motor running and am trying to get the brakes to work. I replaced the rubber line and filled the res back up now the pump runs all the time when the key is on I have gotten a chance to actually drive the car to see what the brakes are like and they seem to be working correctly. The pump did run several times with the res empty for a few min at a time do you think that I fubard the accumulator? or do I just need to blead the system down.
I would bleed them first and make sure all the air is out of the system then go from there .
I had to replace the whole unit on my Mark VII and I used almost a whole quart of fluid just bleeding it .
There is an actual procedure to bleeding that uses the pump , but I dont remember exactly how I did it.
I'm having the same problem.
I thought your brakes were still hard as hell mine seem to be braking just fine the pump just runs whenever the key is on and stays running untill I turn the key off Im going to bleed the system this weekend and see what I come up with.
I guess I missed that part of your post, sorry. I will be watching your results though. Good luck!
If the pump won't shut off, you have either air trapped in the system, a control valve stuck open (sometimes you can see the fluid circulating around the master reservoir), or a fried pump. They don't like to run dry. Did the fluid look metallic at all?
No fluid didn't look metallic. I am guessing that I have air trapped in the system being the hose from the res to the pump came off and the pump ran with no fluid. If this is the case is there any special way other than following the NATO write up on bleeding the brakes?
Forgive me, but I am not sure what the "NATO writeup" refers to.
You can use a scan tool to cycle the pump and valves, but most people don't have access to that easily. You can also run it through some ABS cycled hard stops if the abs light is not on and you have enough brakes to force a lockup situation on soft ground like dirt etc. Alternatively, you could try the hillbilly method- pumping down the pedal (assist pressure) with the key off to dump any accumulator pressure, remove the accumulator and turn the key on for a very short time to let it pump fresh fluid out of the fluid passage to the accumulator. The pump can put out an extremely high pressure, but it's not a huge volume so it shouldn't make too big of a big mess; just don't stand over it. Put the accumulator back on and see if the pump builds pressure. You can rinse off brake fluid with plain water when you're done. You might get it burped out enough to get the pump off until you can drive it and do some ABS stops.
Short of cycling the controllers with the scanner I don't know an easy way to bleed it. I think I still have a TEVES brake system guide in my old dealer tech info stash from my Oldsmobile days. I'll see if I can find it in case I'm missing anything.
http://www.thelincolnmarkviiclub.org/phpBB3/viewtopic.php?f=12&t=463
I dont know what NATO says , but this is how I did my Mark VII
I think in this case we are looking at an air lock in the pump, like it's lost it's prime, if you will. It will be a lot easier on both your leg, and the pump to burp it at the accumulator passage as it is before the rest of the system. The fluid volume should be about the same as you see at the bleeders.
What you don't want to do is to have to push all that air through the whole system if you don't have to. Once the accumulator passage is bled out then continue with bleeding as hypostang above suggests (FYI, that's a great way to bleed the rear brakes circuit in general- great link!). It should go quickly then.
If nothing comes out of the accumulator passage, then there is an inlet blockage to the pump or it's likely toast.
When you say burping it at the accumulator passage are you meaning that I pump the brake 30 or so times with key off then remove the accumulator then turn the key on to let the pump flow to the open port where the accumulator was?
Exactly. Pump the pedal until it is hard as can be- no assist left at all. Do this with the key off (completely out of the ignition cylinder if you want).
Remove the accumulator.
Then turn the key on and let it flush fluid out of the Accumulator hole. This should only take a few seconds, maybe up to 30 I suppose.
Turn the key off and reinstall the accumulator.
Turn the key on and finish bleeding as suggested above if necessary.
I learned something today , I had no idea you could bleed at the accumulator port .
Now I can't wait to see how you make out :D
Sorry, I don't mean to hijack but when you run the pump with the accumulator removed fluid should pretty much gush out of the hole where it was right? I was working on replacing my brake system with my spare unit when I decided to try this after reading oljeeptek's posts. The fluid bubbled up and after about 10 seconds overflowed just for a second then receded for a few seconds of stillness before bubbling up again and beginning the cycle over. Did I just possibly find my problem?
Ok I removed the accumulator let the pump run long enough to turn the key on run to the booster to see if fluid was comming out. Fluid was comming out didn't take long to go through half of the res. Alltho the fluid was not squirting out of the accumulator hole which I really thought that it would be it was more like just a steady overflow. Then I turned the key off reinstalled the accumulator. Still running full time. On to bleeding the brakes maby today if I can talk the wife into pumping the pedal for me.
Oh ya i also tried a different accumulator just to see if the accumulator was bad and both do the same thing.
Fluid flow from the pump will normally be low volume, it doesn't gush out, but it can develop very high press when pumping against resistance. It stores this energy in the accumulator.
If you have clean, clear fluid coming out of the accumulator hole, you're really at the point that a pressure gauge needs to be screwed into the accumulator hole, or the pump output, to check pump output pressure.
The issues here are that the thread size and pressure dictate a specific gauge. You need one capable of measuring 2000 psi. You might be able to rent one from a local parts house, like O'Reilly or Autozone etc. Ideally also you need to "purge" or cycle the solenoid assembly while the pump runs to clear it, but try bleeding it and if there is brakes enough to drive it safely, do some hard brake stops in the dirt. I believe some aftermarket scanners can perform this function too so check with your tool rental shop to see if they have something that can help you with this. (I fortunately had the luxury of the factory tools so I'm not able to direct you which scanners to look for but I would try to get hands on OTC, MPSI, or Snap-on if you can.)
You are either now still fighting the solenoids or the pump went Kaput.
FYI, when an accumulator goes bad, it causes the pump to shut off within a couple seconds with no assist reserve. Normally the pump should run 30 second to a minute after pumping the pedal 4 or 5 times.
Loaded87IROC- your description sounds like your volume output is a little lower than I'd expect.
I forgot to look for my TEVES info last night. I'll try to look tonight.
One more side note; make sure you don't use DOT 5 brake fluid. It's silicone based and it actually is compressible and will give you all kinds of fits with mushy pedal, pressures etc.
Ebay currently has a Breakout box listed at about $30 including shipping. Might be what you need! Search "Teves J-38716". Are we allowed to post an actual link on here?
Now I'm hogging the thread, sorry!
Someone elsewhere suggested that a completely ruptured bladder in an accumulator might allow it to fill with air causing a pump run-on. I have never seen this happen in the field myself, but theoretically it would make sense. You could invert it and fill it with brake fluid prior to reinstalling to check for this. l would probably take a half pint of fluid in this case. I assume your replacement was used?
By the way, what was your original symptom that caused you to replace the pressure switch?
links are OK , and welcome
My original symptoms were the pump would not run at all unless I jumpered out the switch or jumpered the relay. After replacing the switch the pump now runs as described I do think that if bleeding the brakes doesnt solve my problems I will be going to a conventional setup with vac assist instead of the Teves
I stumbled across this link , check it out
http://www.thelincolnmarkviiclub.org/phpBB3/viewtopic.php?f=12&t=3591
Sorry, I've been swamped here.
It looks like you made the correct initial diagnosis with the switch.
Let us know how it works out. Teves is a very simple system actually, but the parts are $$$ and it's tough to work without the guage and a valve actuator. (It was also used by GM for it's Hydroboost system and I've been thinking of adapting one to my 69 Bronco but that's a whole 'nother can o worms.) Good luck anyways!
Hypostang that is a good link with a lot of great info.
Thanks for all of your help but after bleeding the brakes ALOT the wife thinks her right leg is bigger than the other now I will be picking up my SVO M/C in the morning.