Calling All Brake Gurus

[htiek]

Thanks for the suggestions guys,

Another pleasant Sunday and a chance to put a few more miles on the Esprit. Once again, the ABS light would go out for several minutes and the pulsing pedal and noise would return. The noise sounds like it comes from the master cylinder area but it is difficult to locate while driving along! It could simply be normal operation of the solenoid valves and ABS pump.

I had a good look up front and jack etc. are secure, besides, other than occasional operation of the pump, I only hear these thumping sounds when the ABS goes 'operational'.

Anyhow, she goes in on Thursday for a sort-out, the drive home with fully operational ABS (hopefully) should be interesting!

Cheers,

Keith

[Jonathan]

I reakon you have a blocked port in one of the solenoid valves under the reservoir - when they're empty of fluid I know of solenoids that resonate (the fluids dampens the noise).

This could be affecting the system pressure but if the pump is always on (located just behind the front drivers side lamp pod) you have to ask why you're losing pressure, duff pressure switch, internal leak, faulty accumulator ?

This is also why the pedal is going funny.

Fact is if the pump is going that'll be the next thing to fail and so on which is why it's important to fix things as they come along.

If you're garage has access to a TECH 1 scanner, they can (apparently) do all sorts of tests and isolate the fault easily, however even my main dealer doesnt have one - given the number of poeple that have problems with this system it might be worth having a group booking into Lotus at some time - lol perhaps they can sort them all out in 1 go ! ?

Edited January 28, 2008 by Jonathan

[Paul93Lotus]

I have spoken to three Lotus 'specialists', two at dealers and one an independent, and they all seem to think the pulsing, uneven pedal feel is caused by air in the master cylinder that can be very difficult to remove by vacuum bleed or 'pressing the pedal'. The Tech 1 tool has a solenoid bleed procedure that will remove all the air from the system. Like you said...the problem is finding a shop with the Tech 1 and the appropriate brake cartridge plug-in.

I have the original GM Delco Morraine manual...most of it is Tech 1 related, but there is some useful trouble shooting and diagnosis info that will heklp with understanding of the system....I am going to scan the whole thing....it will just need to be hosted.

And a solid yellow abs light is bad news (pending brake failure)....and you should park that car right away...a blinking one is a fault where just the abs may be disabled, but you still have brakes.

My late 93 had none of the issues my 95 has as far as brake feel.

[Jonathan]

Interesting, I have my ABS all in bits at the moment whilst the rad is off - if I can get the next 2 weeks off I might have a crack at solving this as I think I can get mits on a Tech1 and I havea lot of info on the system here (just never had time to rip it all to bits, as you do to your braking system on your days off !).

I'm willing to give anything a go at the moment - air in the system can't be a good thing at all - I wonder what the tech 1 does to bleed it, I could make a simply relay logic controller to simulate the proceedure with ease.

Dunno - just seems everyone who has one of these cars has this problem and gets the old "they all do that sir".

If I get any answers I will of course publish them !

[Paul93Lotus]

The Tech 1 abs bleed procedure cycles the abs solenoids to move the air up and out of the master cyclinder. One tech I spoke to says that the air in the lines compresses and cause the fluid to boil in the lines....thus the weird pedal feel.

My '93 had a very good pedal feel...it may have been "wooden" as some people have described, but I think all systems that work with an accumulator/pump will feel like that. I had even pressure application with my 93...the car stopped promptly (but not anything to write home about), and there was nothing unusual about the feel. I believe it had that "Super Blue" fluid in it...so at some point it had been bled and flushed before I bought it.

I wonder how involved it would be to convert to another GM system....something that could use the existing sensors at the wheels. What cars were the other Kelsey-Hayes systems from? Were both four channel systems?

Edited January 30, 2008 by Paul93Lotus

[karluk29]

ok to jump on the braking bandwagon, i drove mine home from work, abs light came on (as usual) then the RED hanbrake light and "oh hell" no brakes, no servo assists at all, just like driving with no key in. THEN 5 mins later all back to normal.

but this has now happened about 10 times this week, not good.

would mine be the pressure switch? and is there another pressure switch not just the stoopid expensive one? as i swear i had one before and it was

[Paul93Lotus]

There is only one switch within the system...the stupid expensive one.

Couple of scenarios.....

If the pressure switch is failing, then it will not kick on the pump, which recharges the accumulator with stored up pressure. After a couple of presses, you run out of pressure in the accumulator, and the resulting no assist.

If the accumulator is bad, usually the pump will be running all the time, as the pressure switch is never satisfied with the pressure and keeps trying to recharge it.

If the pump is bad, you get the same sympton as a bad pressure switch....no recharging of the accumulator. You can jumper the pump to see if it is working with a 12V source. The pumps seem to rarely fail though, unless someone drives forever with the pump running due to a bad accumulator/pressure switch. You should listen up front to see if the pump is running all the time.

The part that sucks for you is that you obviously have an intermittent. A blinking abs light just means that the abs has been disabled, but the brakes will still function properly. A solid yellow abs fault means there is a serious problem (somewhere in the hydraulics).... The red brake and yellow abs means complete brake failure. You see that again you likely have no brakes or "one" push left.

[Dasar7]

I'm back to square 1: adjusted RHF brake sensor & checked out all ok, but still have b#&@$#y ABS light flashing at me. Pressure switch & Accumulator procedure all seems to check out, back to scratching heads.

[karluk29]

is there any other braking system on the planet that uses the same pressure switch, as

[Jonathan]

TBH after 2 you might as well have gone for a different system !

If I cannot sort mine I will simply put a dual master cylinder in there and be done with it - no ABS.

Personally I like ABS but I'm not made of money - perhaps the newer system can be copied across ?

Again I can't see how the switch can cost

[fflyingdog]

TBH after 2 you might as well have gone for a different system !

If I cannot sort mine I will simply put a dual master cylinder in there and be done with it - no ABS.

Personally I like ABS but I'm not made of money - perhaps the newer system can be copied across ?

Again I can't see how the switch can cost

[Jonathan]

Ahhhhhaaaaaaaaaa

There is an easier route - (I'm so on the ball today it's bloody scarey)

> Thermal cut out fuse.

Basically put it inline with the electrics, when the pump starts to struggle it draws more current - bosh, fuse cuts out.

Basic counting circuit on the brake switch, 3 pushes later off we go again.....lol probably hasn't a hope in hell of working but ya never know. You'd have to get it pretty spot on or blow the system to bits as the pump over runs LOL BANG !

On a serious note I wonder if that's actually a good idea - it could be done with current draw but not sure how accuratly you'd get it.

Safer bet is to ditch the whole lot and go for a twin standard mastercylinder imo.

Found this :

http://www.autozone.com/az/cds/en_us/09008...irInfoPages.htm

Thing is it might not be the pressure switch at all - looking and reading through it could be a combination of a lot of things - an internal leak is an example.

Also interesting............just over 1/2 way down

http://www.babcox.com/editorial/bf/bf70518.htm

[karluk29]

so what other cars have the same system as the gt3/s4/s4s then? are there any?

[Jonathan]

Yeah they are all funny American things though, as far as I know none in the UK.

OLDER INTEGRAL ABS SYSTEMS

Integral ABS systems were discontinued long ago, but you may still encounter this type of ABS system on some older vehicles. The GM applications include the Delco III Powermaster system on 1989-91 Buick Regal, Oldsmobile Cutlass and Pontiac Grand Prix and GTU models. It is functionally similar to the Teves Mark 2, Bosch III and Bendix 9 and Bendix 10

integral ABS systems used on older GM, Ford and Chrysler vehicles.

Integral ABS systems use a high pressure pump and accumulator for power assisted braking as well as anti-lock braking. As a rule, the accumulator must be depressurized before doing any type of brake repair work. Some of these systems can produce pressures of up to 2,700 psi, so never open a brake line or attempt to replace any of the ABS hydraulic components until the accumulator has been fully depressurized. This is done by pumping the brake pedal firmly 40 times with the ignition off.

After repairs have been made, the lines can be bled manually, with a conventional power bleeder, injector tool or vacuum bleeder. With all of these methods, leave the key off so the ABS pump does not pressurize the accumulator. Each of the brakes can then be bled in the usual manner following the sequence recommended by the vehicle manufacturer. On the GM cars, the usual sequence is right rear, left rear, right front and left front.

If the master cylinder or ABS modulator has been replaced, or there is air in either unit, the ABS modulator will have to be bled using a specific procedure. On the older GM applications with the Powermaster III ABS system, here

[sid1]

Hi everybody,

have mostly the same problems with my 91 SE , after the accumulator was changed to a new one from PUK the ABS light goes off. Have the same problem with pedal feeling and very poor brake performance and the pump runs to often (after two or three steps on the brake).

My next project will be to throw away the Delco Powermaster System and replace with a standard master cylinder with vacuum assistance, I have to check in the workshop manuals what is really the difference between the SE with ABS and the normal turbo without ABS.

By the way, has anyone done this modification or know one who did it or has an idea from whom i can buy a standard vacuum assisted mastercylinder for an SE or knows if the turbo master cylinder will fit in the SE?

cheers andre

[Paula&Marcus]

Haha ... Andre,

The problem is: "Where to get the vacuum ???"

Your car has NO vacuum pump that is able to assist the brakes, and the engine itself does not generate sufficient vacuum (= relativeley small displacement + turbo).

Thats why they actually put in that Powermaster III system.

The PM III is not too bad at all. Once you got around it and understand fully how it is working its a very well operating system, IMHO.

Do you have the ABS IIIA manual (Section JF) ? Its essential !

Cheers

Marcus

Hi everybody,

have mostly the same problems with my 91 SE , after the accumulator was changed to a new one from PUK the ABS light goes off. Have the same problem with pedal feeling and very poor brake performance and the pump runs to often (after two or three steps on the brake).

My next project will be to throw away the Delco Powermaster System and replace with a standard master cylinder with vacuum assistance, I have to check in the workshop manuals what is really the difference between the SE with ABS and the normal turbo without ABS.

By the way, has anyone done this modification or know one who did it or has an idea from whom i can buy a standard vacuum assisted mastercylinder for an SE or knows if the turbo master cylinder will fit in the SE?

cheers andre

Edited February 5, 2008 by Paula&Marcus

[karluk29]

does anyone know off the top of there heads what USA cars run the same system as i have friend that maybe able to source parts from the states quite easily

[MGFCrasher]

I was told reliably that the uk Jeep cherokee used the same system in the 90's.

I saw a 4 ltr one of those with an MOT the other day for

[karluk29]

well it looks like a buick regal, so i have my man on the case to see if this is true. will look at the jeep option aswell.

DELCO POWERMASTER 3 ABS (4-wheel, Integral)

1989 to 1991 Buick Regal

1989 to 1991 Oldsmobile Cutlass

1989 to 1991 Pontiac Grand Prix

1990 to 1991 Pontiac Grand Prix GTU

Edited February 5, 2008 by karluk29

[Jonathan]

Just got this image of karls Friend running around pinching all the ABS pressure sensors off these cars, doing a full circle and some poor bugger with a Buick whatshisface going "what other car has xxx pressure switch" and someone saying "hmmm Lotus Esprit"

[Paul93Lotus]

Karl....the Pontiac one is from a Pontiac "Turbo" Grand Prix. Which are about as rare as Loti. This was an "optional" brake system. The car list you have is correct, but most will have the standard vacuum assist system. He may get lucky though if he hits enough yards. The problem is that a lot of these cars end up at the wrecker BECAUSE of the powermaster III is so expensive to fix.

I know Prior remanufacturing....the company that rebuilds these things in Texas, puts new ones on their rebuilt units, so maybe they will sell just the switch?

I have seen on a list of abs equipped cars that the Kelsey Hayes EBC430 system (as on V8's) is also on 99-01 Ford Windstar minivans.....maybe that is a more pliable system conversion?

I am not so sure that the Esprit does not produce enough vacuum as Marcus says. How is it that almost all other turbo cars have standard vacuum boosters? What makes the Esprit's 4-pot motor so special to produce no vacuum? The powermaster III was the height of technology at the time for GM cars....I think that system was more of a compact packaging system than made for cars with low vacuum....All of the GM cars except maybe the turbo grand prix produced more than enough vacuum to run off a standard vaccum booster set-up. This was basically an in-house produced set-up as an alternative to the Bosch system used in the Vette. I have read on a lot of "W-car" forums that conversion to the standard brake system is a common remedy to ditching the PM III...but I think in our case there might not be enough space because of the size of the booster.

Edited February 5, 2008 by Paul93Lotus

[karluk29]

i just cant get over the damn price of these switches, and the failure rate of them. i think lotus should have a half price sale LOL

[fjmuurling]

Maybe this is worth further investigating: http://ashcroft.com/products.cfm?doc_id=261

Freek

Edited February 6, 2008 by fjmuurling

[sid1]

Haha ... Andre,

The problem is: "Where to get the vacuum ???"

Your car has NO vacuum pump that is able to assist the brakes, and the engine itself does not generate sufficient vacuum (= relativeley small displacement + turbo).

Thats why they actually put in that Powermaster III system.

The PM III is not too bad at all. Once you got around it and understand fully how it is working its a very well operating system, IMHO.

Do you have the ABS IIIA manual (Section JF) ? Its essential !

Cheers

Marcus

Hi marcus!

you mean the existing vacuum pump did not provide enough vacuum, i thought an electric vacuum pump from any other car (turbo diesel) could be fitted? as you mentioned, the PM III ABS is not too bad, for my experience the breaking performance is lets say between poor and average. by the way greenstuff pads and ebc disks are installed. the part of the workshop manual with ABS is the most used:-).

andre

[esprits4de]

I have found the black variant ( GM part number) last spring in the US. Got three pcs. which have been sold already, but after that my supplier was not able to locate this switch anymore. I am sure that there are still some out there,sitting on a shelf in some workshop, but unless these shops are linked to a parts trader online system, they will probably still lie on those shelves when our cars are dust.

I hope to find an alternative in europe some time soon....

And yes, 99% of the time it is this stupid switch ! I spent 2 years doing trial and error replacements to narrow it down....