I'm having FI issues right now, lots of them. Today I got to the point of taking the MPS out of my 1.7 DD and put it into my 2.0 recent resto. I was surprised to see that the MPS out of my DD wouldn't hold vacuum. Being number 4 MPS to take apart this week I was only able to find one of them with a good diaphragm and that one I put into my 2.0.
Changing them really wasn't a big deal,(2 out of 10 for difficulty) but setting them up afterwords might be trickyer. As long as the original settings were maintained the car should run better than with a cracked diaphragm????

With most of these MPS's over 35 years old, there cannot be many of them still in good condition. I would be leery of buying used only to have it fail soon after buying. How hard would it be to have a batch of 200 diaphragms made up. I'm sure they would sell.

BTW - took a good quality packing type tape and sealed up one side (outside) of the diaphragm and put it back into my DD. Very short term fix but it seemed to run a bit better for now. It can't be any worse than running with 2 big cracks 50% of the way around the old diaphragm.
Just a thought.

This was discussed many moons ago ad nauseum. Because of their compostion, they probably cannot be made in the US of the appropriate materials.

To create the die for stamping would have been costly from what I remember.

Brett Instruments (now Fuel Injection Corp) tried using a steel stamping but due to flexibility characterics, it didn't work well.

Best way is to buy used from any vehicle that used D-Jet (Audi, BMW, Volvo, VW, etc.,) and try to find one that holds vacuum. Remove the diaphram and place it in the one you need (or at least that's what I think would be the best solution).

Otherwise ..... by an aftermarket EFI setup that uses current components.

Geoff Blyseng used to repair them and had the ability to adjust them.

Another case of our congress knee-capping US manufacturers with ludicrous regulations and then blaming those same manufacturers for moving jobs overseas.

Just an observation. Not meaning to

Then don't post inflammatory political comments that are irrelevant.

Doug:

I would be very interested in such a purchase. However, I question if it is even possible to do. I just went through this with my D-jet. Found my diaphram to be cracked, ordered two used ones (as you know, they are not cheap) and got only one that actually worked.

Please let me know if you come up with anything.

Bob

wow, that wasn't just from left field, it was from the minor league ballpark across town...


I don't know about the MPS composition, but I agree with SLITS, replacing it with a modern replacement or using a used one is the only ways I can see to fix the issue. but there has been talk of Bosch re-manufacturing many parts again... and I would hope the MPS or MPS diaphram would be high on that list.

from my memory and the old discussions
the diaphram had nothing to do with congress or small business

its the actual material that is the problem
the original diaphram had (was it?) beryllium in it
the alloy characteristics made it good for the specifications that were used to design the MPS

the replacement diaphrams of other alloys do now work well due to their different compound characteristics...

I'm not blaming congress for trying to reduce radiation and cancer safety..


by the way to the original thread starter.
you MUST have your MPS recalibrated to keep the motor happy and get the correct AFR's now that you've "rebuilt" it.

brant

It's a Beryllium / copper alloy that cannot be produced in the US as the "B" part is the problem.

And I don't consider BigKenSteele's comment to be inflamatory ... it's just the truth (and applies to many more things than this issue).

Primarily what you want in a used MPS from ANY car is a vacuum test. If it holds, the probability is the diaphram is good. Other leak areas could be the seals around the electrical connector and/or the case halves. The rebuilders I talk to do just what I described earlier.

Next best option would be for someone with adequate knowledge that can detail the electrical impulse characteristics to match up those characteristics with a modern MPS (like used on a Jeep). I don't have the knowledge so I ain't gonna try.

As far as Bosch reproducing the MPS ... don't hold your breath as you might turn really blue. Market is to limited to gear up for production.

Be, even be-copper is available in the US. It does not cause cancer or make your testies fall off. It's BE dust that causes problems very close to asbestos problems in the lungs. BE Copper has never been a problem, since the BE is bonded in the copper in small amounts. It can not get airborne to case problems. And you must be "allergic" or sensitized to BE to even be a problem. Wyman Gordon is the US's largest producer of BE products, and your golf clubs probably have BE Copper in them still today. Tooling however to stamp these out would be expensive.

Like Slits said....we went down this road, but I wont discourage anyone from trying again.

At the time, we could not find a machine shop that would work on BE copper in such a small run.

Like was said above, it is used in certain products, unfortunately, BE copper requires a sealed chamber to reduce the affects of the dust and the main shops that use it are aerospace shops.....and they dont sub out work.

Given the current available bandwidth in the automotive industry, it may be easier to find a shop that will make a run or several hundred for a reasonable price.

I suspect the deal would be easiest if you contact and find the BE machine shop that is setup to do this, then involve fuel Injection corp to see if the tooling still exists.

I am willing to bet you could sell 100 right here.

Rich

Sealed chamber?? Not quite. Just need approved Hepa ventilation, and tyvek suits. I know of at least 2 shops in Santa Clara alone that do BE copper. They will not do straight BE. They are also starving to death in this economy. It would be a good time to try again.

Step up to the plate my friend...
I know Geoff and myself have tried in the past.

Let us know what you find out please...I would sure buy more than a few.

Rich

I'll get in touch with the lead in one of the shops, see what he says.

Fuel Injection Corp/Brett Instruments may have tooling.

Rich

How is Fuel Inj corp reproduceing the diaphrams? Was just thinking that Rich.

Last time I checked we found that they had made a run of tin diaphrams quite a few years ago and they were getting close to running out.

It was either tin or brass they used.

Rich

Looks more like brass/copper, I just took one apart to reseal it. Seems the curves are not as smooth as the original materials from what we seen on prior posts with graphs.

Well, if Bob Smith (Fuel Injection Corporation) would let you talk to Don (ex-owner) of Brett Instruments, you might get some information. I had one run in with him and won't talk to him again ... I don't even like to sell them cores.

Secondly, you would have to talk to Bosch GMBH to find out the characteristics of the alloy they used to match the flex characteristics. Like Porsche and many others, they may not be forthcoming with the information.

I suppose you could have one analyzed to see if the alloy could be duplicated.

I'm speculating here ... I know the rebuilding end (the exowner of Python is a personal friend), but I don't know the production end of the disc other than the die would probably be very expensive.

I know that Python Industries and Fuel Injection Corporation, for two, would probably be interested in obtaining them. MB owners were clamoring for rebuilt MPSs at one time (not to mention Volvo, BMW, VW, etc). Getting rebuilders to pay their bills might be quirky. None are doing really well at this time.

Thirdly, could one access the seals used around the electrical plug and housing halves. I have seen some rebuilt that used gasket material in an attempt to get a seal,

Geoff used a WaveTech to calibrate them as far as I remember. You would have to have a new unit to get the values as I remember.

Oh well .... Good Luck ... I would like to see it happen

Search here or on the other site.
A metal guy tested the hardness etc and posted the results.

This is 3-4 years ago.

Rich

Try this One for Info

We are such a bunch of loosers...we cant even get a BBQ arranged.....lol

Getting that done was a pipe dream...lol

Maybe the next guy up at the plate will have more success.

Rich

I took five MPS apart last year. I brought them in to work and analyzed them using XRF- X-Ray fluorescence- which non-destructively determines alloy composition. I have the actual alloy materials, but I'm off site today. I'll post them this weekend.

Bottom line-
stock- virtually pure copper
aftermarket1- pure copper, 2 pleats, but very nice workmanship.
aftermarket2- stainless steel, otherwise a perfect repro of stock.
aftermarket3,4,5- brass, 3 pleats, very poor workmanship.

The brass diaphrams have bad ripples around the perimeter where they're supposed to seal to the housing. This causes a slow leak. Also, the brass pieces are stiffer and thicker than either the copper or stainless pieces. One of these was from a newly refurbished unit (still in the box with the receipt) from a well-regarded 914 parts supplier. I took it apart because of the slow leak.

The most flexible is the stainless steel one. Interestingly, that unit also had stainless aneroid cells. The others cells were pure copper. The workmanship is so perfect that it makes me suspect that Bosch may have switched to stainless near the end of production to try and reduce fatigue failures. I can't imagine an aftermarket manufacturer tooling the aneroid cells, as they don't tend to fail, meaning any rebuilder would have lots of good used ones from MPS that failed for other reasons.

Other thing I noticed, kinda off topic, is that the aneroid cells contain a partial vacuum. This is contrary to some reports that they are charged to one atmosphere.

Jim