MPS copper diaphgram problems

[lmcchesney]

Help guys,
I recieved my 2.0L D-jet FI system today. Cleaned and inspected. Measured resistance/ohms on the MPS and looks good. Large leak.
Marked casing. Casing number -----049. Ground off rivets. Opened casing and inside ink marked 52 on bellows and scribed on partition 52. Removed bellows. Unscrewed retaining ring and partition. Center of copper diaphgram falls out. The copper diaphgram completely seperated from rim. UGHHHHHH.
Question:
I have a good copper diaphgram from my old MPS ----039. Is this the same and can it be subsituted for the copper diaphgram in the ---049?
Is it a functional repair to braise/soder the rim of the diaphgram back to the center of the diaphgram?
Or do I just start all over in search for another ---049 MPS?
Thanks,
L. McChesney
lamcchesney@netzero.net

[Alfred1]

Jeff Bowlsby or Geoff Bleyseng could probably help you since they rebuild MPS's.

[lmcchesney]

Thanks Jeff,
I was hoping Geoff or Ray would have an idea. I know Ray Green molds and makes copper diaphgrams.
L. McChesney

[bowlsby]

Ray 'said' he was fabricating the diaphragms...thats as far as they have progressed as far as I know. I keep meaning to do them, just other projects seem to get in the way...

Jeff

[Alfred1]

Originally posted by bowlsby
I keep meaning to do them, just other projects seem to get in the way...

Jeff

Please, please, please, please, puh-lease?! Actually, I was thinking of taking the diaphragm from my MPS around to some people (engineers/metallurgists etc.) around here and seeing if they couldn't "reverse engineer" it to duplicate its characteristics exactly. Then I could have a hundred or so made up and sell 'em on ebay. Of course, this would all depend on cost.

[bowlsby]

Ok, I can't do everything...so why not share my ideas for the diaphragm?...On the sole condition that they be made inexpensively available to everyone if it works. Lets see if anyone else is willing to fab these up.

McMaster-Carr has copper and bronze (I think) strip available inexpensively in the right thickness.

Fabricate a jig, from a solid hardwood block...Oak...or better Nylon or...aluminum...or whatever you have the ability to machine. Cut concentric ripples into the surface of the jig to match the MPS diaphragm pattern exactly.

Fab a center axial hinge from an eyehook or threaded center post at the center of the jig, to then attach a threaded lever-arm with washers and spacers on it, which will emboss the diapgragm with the correct pleat pattern.

Drill the center of the pleated diaphragm to accept the center stops from the core MPS and press the center stops into the new diaphragm. You'll need a prying tool to remove it from the core and a pressing tool to reinstall it. Cut the outside diameter to the correct diameter and mount into the MPS case. Test for vacuum leaks and redo you work so that it does not leak in the vacuum test.

Send it to me or any of us that can recalibrate it to the correct settings.

Think it will work? I think so...

Go for it and post the results...

[Dave at Pelican Parts]

Or try the one from your other MPS. I don't believe they are different.

Soldering and brazing are possible, but the diaphragm will be weak and will fail again eventually in that same spot. Don't know how long "eventually" is. The flexing characteristics may also be changed, which may change how the car reacts to full-throttle loads.

All three ways are valid. If you make new diaphragms, you will benefit a lot of 914'ers.

--DD

[joes]

I think that the diaphragm may not have atmospheric pressure in it. I don't know if it is positive or negative pressure but you may want to factor that into your decision to try to repair it. (junk it!) Look at engine thermostat that must have negative pressure in it (cold)

[mike_the_man]

If somebody made new diaphragms I would be in for a few, assuming they weren't too expensive. I've recalibrated one out of a Volvo to work in my 914, but I think it might be a little off. I also took a diaphragm out of a Volvo MPS and put it in my 2.0L MPS and re-calibrated it. They both work pretty good.

joes, I think that you're thinking of the Aneroid(sp?) cells in the MPS. They're pressurized somehow, I believe. The diaphragm is just a flat copper sheet with ripples in it.