Lost brakes and steering---sudden

[a]

Due to the age of the car and its components. You are lucky if anything works. Of course, some of it is bound to be a bit wonky . As a mechanic from a different machine, if you are serious , get yourself a Bentley manual for the E 28. You prolly have all the tools you need already. Down load the highlighted link in my sig for the electrical manual. And you're all set. The E 28 is a very easy car to wrench on compared to newer cars. Which is good , because they average 2K$ to put into service. That figure is old and certainly is better to figure 2.5-3k $ now-a-days. Figure that should give 5-7 yrs of decent runnings. With additional upkeep of course.

[edmon59]

A

This is why a bad bomb has a soft pedal at first, no pressure from the reservoir and the PFR is trying to get that pressure and does get it from the pump and steering and the brake pedal firms up. This moment of terror as you stab the brakes and the pedal falls an inch or two. If the pedal does not firm up, you are then be using manual brakes which require huge pressure from you on the pedal, but you will stop the car. I have not had that happen on a car while running.

Wondering if the loss of power that Paul is talking about is much longer than the transient losses I've mentioned?

Well put. I have had my "panic" moments when while applying brakes I had a rock- hard nothing response to the pedal. A second panic stab got me some results. What happened the other day, the reason for my OP, is that I lost steering and brakes much like what would happen in my nasty gas tank/plugged fuel filter days.....everything would just go dead as if the engine had died (it had)---at highway speeds.

I lost the steering and brakes simultaneously on dry pavement after gassing up at a local Conoco. ....Full tank at all times since rusty fuel issues.....
Seems I have two ways to go, sort of. I know I need an accumulator, I just need to check pressures on the pump. Might need both, eh?

Oh, to the gent that suggested I get one.... I already have a Bentley manual.... It was my first purchase ( after the car of course)
Regards,
-Ed

Pulleys, belt, fluid all good.

[Blue Shadow]

everything would just go dead as if the engine had died (it had)---at highway speeds.

I lost the steering and brakes simultaneously on dry pavement after gassing up at a local Conoco.

These are the only two data points you put in your most recent post. From what you are saying we can ignore the first as you said the motor was not running (the only way steering is powered). The second does not give any indication of the length of the loss of power fluid. I think that conoco has something to do with it.

Don't get all gung ho about measuring pressures, you are in the 2300 psi range here. You need a good bomb which holds pressure for the brakes until the pressure is used by the brakes whether the car is running or not. This leaves the pump free to handle the power steering because the bomb will hold about 10 brake pedal applications. So the bombs demand on the pump is not noticed while driving as it is not "must supply 100% power to the brakes" as happens when the bomb is bad.

Without good data and the correct operating characteristics when the issues occur, all I can say is drop it off and we'll look at it. Know what I mean???

And we're doing this over the interweb so it is long distance in many cases. Change the bomb, report back.

[edmon59]

Imprecise. True. Here is what happened.

I went to a gas station with a normally functioning car. I drove about 1/2 mile afterward and had total power brake and steering failure, failure that would be similar to engine failure (loss of brake and steering function). My engine and other systems were and are operating just fine .
I got the car home, checked belts, fluid, etc.... no issues except for the known failing accumulator.

FWIW, Until I cleaned my fuel tank with muratic acid (long but ultimately successful story) I had severe fuel filter/starvation issues due to rust...the car would die on the freeway...I carried lots of filters and knew the signs of "filter time" Learning curve stuff.....rust kills fuel pumps too,I learned the hard way. One problem fixed, another to address. Such is life with these cars. FWIW I've got well over $3K into repairs on this one, and it's still not roadworthy......this must be love.
-Ed

[edmon59]

everything would just go dead as if the engine had died (it had)---at highway speeds.

I lost the steering and brakes simultaneously on dry pavement after gassing up at a local Conoco.

Don't get all gung ho about measuring pressures, you are in the 2300 psi range here.

Without good data and the correct operating characteristics when the issues occur, all I can say is drop it off and we'll look at it. Know what I mean???

I work (get paid to work) on hydraulics, I spend all day measuring this stuff. The pump tests out or it doesn't, period. In my field 2500 psi is aux (ancillary) pressure, my mains run in the 9500-10000 psi range. Just sayin.
-Ed

[edmon59]

everything would just go dead as if the engine had died (it had)---at highway speeds.

I lost the steering and brakes simultaneously on dry pavement after gassing up at a local Conoco.

Don't get all gung ho about measuring pressures, you are in the 2300 psi range here.

Without good data and the correct operating characteristics when the issues occur, all I can say is drop it off and we'll look at it. Know what I mean???

I work (get paid to work) on hydraulics, I spend all day measuring this stuff. The pump tests out or it doesn't, period. In my field 2500 psi is aux (ancillary) pressure, my mains run in the 9500-10000 psi range. Just sayin. I do however see the point you are making and I'll take it into consideration.

Thanks for sharing.
-Ed

[Blue Shadow]

Well if you are in the hydraulics business the pressure test explained in the Bentley will be child's play.

Complete failure of the pressure system from the refueling with Conoco. Is it still failed, does it come back at all?

Is the fluid getting hot.

Is the fluid getting foamy?

Have you checked the fluid level, I was going to say the right way, but your bomb is busted (if you get that terror brake pedal softness before braking really happens and the dash light is on or flashing) and the proper procedure empties the bomb to get correct level. A broken bomb will not give up its fluid.

So the bad bomb can be diagnosed in another way, the lack of fluid level increase with the car off when the brakes are pressed a few times. Unloading the bomb by pressing the brakes about 15 times (car off) is specified in the fluid level check.

Without knowing how long the power was gone and whether it has come back, changing the bad bomb that you indicated is in the system should be done. If you have a long outage of power and everything is perfect, check that the belt is actually turning the pump. It is not a complicated system other than the completely unknown guts of the PFR.

[edmon59]

Completely failed. FWIW I'm seeing no circulation in the PS reservoir. Got a foot of snow yesterday with more on the way, the bimmer will have to wait..
-Ed

[edmon59]

Found it!

I took a look at the PS pump again and noticed the pulley seemed to not line up with the others. I loosened the belt and attempted to pull the pulley off of the shaft. Instead, the pulley and input shaft started coming out as a unit. Not good. Something snapped inside. I'll pull it tomorrow for the postmortem.

-Ed

[Blue Shadow]

broken pump. That could well be the problem and we haven't seen it before. We have seen the engine running and nothing up front turning. Broken key on the front of the motor.

Glad we are getting this one sorted.

[Kyle in NO]

Hmmmm, really.

If you have no pressure, and the system has fluid, and the filter screen isn't clogged, you need a replacement pump.

The pump input shaft shearing in the manner you describe is about the only way these pumps fail all at once. I've seen it several times.

[533i_Guy]

Found it!

I took a look at the PS pump again and noticed the pulley seemed to not line up with the others. I loosened the belt and attempted to pull the pulley off of the shaft. Instead, the pulley and input shaft started coming out as a unit. Not good. Something snapped inside. I'll pull it tomorrow for the postmortem.

-Ed

As I was reading through the thread, it sounded like this was the problem to me (ex navy, we have snapped pump shafts every now and again in the engine room. Everything runs fine except no pressure in system usually means sheared pump shaft)

[mooseheadm5]

Well there's your problem!

Replace the PS pump and the bomb. Not a bad idea to go ahead and flush the system, too.

[Blue Shadow]

Look at the bright side, the OP now has the ETM, a full understanding of the power fluid system and a suspect part to replace along with the bomb.

[edmon59]

Well there's your problem!

Replace the PS pump and the bomb. Not a bad idea to go ahead and flush the system, too.

Yes, yes and yes. It was your post in this thread about the loose pulley kicking around in the back of my mind that got me to take a closer look in that area. Thanks!
Knowledge is indeed power.
-Ed