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> MPS, Rebuilding the MPS
Ron914
post May 8 2025, 05:06 PM
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Hello to all who have helped me with this project . @emerygt350 ,@TJB/914, @Superhawk996 , @ChrisFoley , @rjames , @MDTerp
I am in the middle of rebuilding my MPS and have a couple of comments and questions .
First when I opened up the unit I found the most difficult job was removing the rivets holding the two halves together.
When I removed the retainer plate to take out the old diaphragm it was in two pieces .
Attached Image
I needed to take two measurements since I was replacing the stop screw , I needed to measure the the stop screw protrusion into the housing . The instruction sheet sent to me by a member had the measurements he must have made when rebuilding his MPS . His stop screw protrusion was 1.97mm and mine only measured 1.72mm.
His inner/outer screw assembly depth in the old diaphragm measured 6.51mm .
Here's one of my questions ?
when I measured mine I got two measurements depth to inner/outer screw assembly was 4.03
and depth to the washer outside the inner/outer screw assembly was 5.46mm.
Again there is a difference and since mine was never accessed before (epoxy over screw was not disturbed) is the difference in measurements ok and which measurement should I use I will try to attach a photo or two to help with my question.
this one .
Attached Image
I have not touched either of these measurements yet and awaiting any help/comments.
I think it's this one to the washer on diaphragm .
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Superhawk996
post May 8 2025, 06:36 PM
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There you have it, now you know why it was a leaker. Good job! (IMG:style_emoticons/default/smilie_pokal.gif) The last unit I did had a diaphragm do exactly the same thing upon disassembly.

The measurements are just to get you close . . . In the ballpark . . . Instead of being way out just randomly assembling. It will ultimately still need tuning which is why you have the tuning tools too.

Pay attention to reassembly directions - gasket placement matters. Chris’ instructions will get you there.
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MDTerp
post May 8 2025, 08:17 PM
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QUOTE(Superhawk996 @ May 8 2025, 08:36 PM) *

There you have it, now you know why it was a leaker. Good job! (IMG:style_emoticons/default/smilie_pokal.gif) The last unit I did had a diaphragm do exactly the same thing upon disassembly.

The measurements are just to get you close . . . In the ballpark . . . Instead of being way out just randomly assembling. It will ultimately still need tuning which is why you have the tuning tools too.

Pay attention to reassembly directions - gasket placement matters. Chris’ instructions will get you there.


I agree the measurements just get you close when you reassemble everything. I wouldn’t worry that your numbers are off from mine. I would just reassemble back to your measurements and use the same reference points when measuring the new parts.
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