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> Did altitude just blow out 2 MPS's?, Put the in my checked baggage...now won't hold vac.
FlacaProductions
post Aug 20 2025, 11:19 AM
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Brought two of my 3 MPS back to L.A. from Indiana while I await the arrival of my LCR55A so that I could do some bench plotting and tuning only to find that neither one of the now holds any sort of a vacuum.

Both ran fine in the car before flight - just needed some adjustment. One has the factory plug replaced with a Tangerine model - the other is still factory sealed.

Did being in the unpressurized cargo area in my checked baggage blow them both?

That would really stink....

Brian
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FlacaProductions
post Aug 20 2025, 08:59 PM
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Well. It’s back together and it’s holding SOME vac now.
Like 20 seconds worth but that’s better than the NONE of before.
I’m suspecting the rubber seal around the outside?
As I first mentioned, the outer four bolts seemed a little looser than I thought they should be but this is the first time I’ve had one apart.
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Olympic 914
post Aug 21 2025, 08:46 AM
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QUOTE(FlacaProductions @ Aug 20 2025, 10:59 PM) *

Well. It’s back together and it’s holding SOME vac now.
Like 20 seconds worth but that’s better than the NONE of before.
I’m suspecting the rubber seal around the outside?
As I first mentioned, the outer four bolts seemed a little looser than I thought they should be but this is the first time I’ve had one apart.


There is no time, when it is running that the diaphragm is required to hold an absolute vacuum. It is constantly pulling vacuum and changing.

Although many will disagree with this, IMHO a 20 sec leakdown should not or only minimally effect the running.
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JeffBowlsby
post Aug 21 2025, 01:54 PM
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QUOTE


There is no time, when it is running that the diaphragm is required to hold an absolute vacuum. It is constantly pulling vacuum and changing.

Although many will disagree with this, IMHO a 20 sec leakdown should not or only minimally effect the running.


That broad statement is a bit misleading and factually incorrect Tom. Care to expound on your perspective for the audience?
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Posts in this topic
FlacaProductions   Did altitude just blow out 2 MPS's?   Aug 20 2025, 11:19 AM
flipb   The cargo hold in modern jets is pressurized. The ...   Aug 20 2025, 11:25 AM
FlacaProductions   They were well packed and padded. F me.   Aug 20 2025, 11:33 AM
ctc911ctc   Considering that the ALPS and the Rockies were tho...   Aug 20 2025, 01:01 PM
emerygt350   Considering that the ALPS and the Rockies were th...   Aug 20 2025, 01:17 PM
ctc911ctc   Thinking back I broke one by selecting PRESSURE ra...   Aug 20 2025, 01:21 PM
ctc911ctc   If the MPS was in a 10,000 cabin and then both ...   Aug 20 2025, 01:36 PM
JamesM   I think the danger would have been in the expans...   Aug 20 2025, 09:33 PM
FlacaProductions   I just put two vacuum pumps on each one here in LA...   Aug 20 2025, 01:17 PM
FlacaProductions   This might have just been a bridge too far for me.   Aug 20 2025, 01:21 PM
FlacaProductions   that's the thing. no more diaphragms.   Aug 20 2025, 01:23 PM
burlybryan   Your bag wasn't searched and the MPS's ...   Aug 20 2025, 01:43 PM
ChrisFoley   Here's what I thought of: The reduced atmosphe...   Aug 20 2025, 02:35 PM
JeffBowlsby   Here's what I thought of: The reduced atmosph...   Aug 20 2025, 05:40 PM
JeffBowlsby   Here's what I thought of: The reduced atmosph...   Aug 20 2025, 05:50 PM
emerygt350   The whole thing is a sealed area. Two forms of mo...   Aug 20 2025, 02:36 PM
ChrisFoley   The whole thing is a sealed area. Two forms of m...   Aug 20 2025, 02:37 PM
FlacaProductions   I’ll crack the unsealed one asap and report back...   Aug 20 2025, 02:50 PM
Spoke   The MPS senses the difference in pressure from amb...   Aug 20 2025, 02:53 PM
emerygt350   The diaphragm itself is a sealed vessel. Containi...   Aug 20 2025, 03:15 PM
FlacaProductions   Here's the pics. First time I've had one o...   Aug 20 2025, 04:50 PM
FlacaProductions   RE: Did altitude just blow out 2 MPS's?   Aug 20 2025, 04:50 PM
FlacaProductions   AND....how do i put it back together?!   Aug 20 2025, 04:57 PM
rjames   If the diaphragm isn't cracked and the seals a...   Aug 20 2025, 05:06 PM
FlacaProductions   I could use some of that tequila right now.   Aug 20 2025, 05:17 PM
JeffBowlsby   Post photos of the front/back of the diaphragm ple...   Aug 20 2025, 05:20 PM
emerygt350   You can test if the cell is doing what it should b...   Aug 20 2025, 05:33 PM
FlacaProductions   I don't see any breaches. I've held it up...   Aug 20 2025, 05:51 PM
ChrisFoley   I've gently flexed it all around and don...   Aug 20 2025, 06:09 PM
FlacaProductions   No cracks. I would think that it’ll tear or clic...   Aug 20 2025, 07:41 PM
FlacaProductions   Well. It’s back together and it’s holding SOME...   Aug 20 2025, 08:59 PM
Olympic 914   Well. It’s back together and it’s holding SOM...   Aug 21 2025, 08:46 AM
JeffBowlsby   That broad statement is a bit misleading and fac...   Aug 21 2025, 01:54 PM
Superhawk996   Grease the paper gasket (very lightly) that is a f...   Aug 20 2025, 09:18 PM
IronHillRestorations   My guess is your suitcase got tossed by baggage ha...   Aug 21 2025, 05:25 AM
bdstone914   I once shipped a good MPS and it was dead on arriv...   Aug 21 2025, 05:40 AM
FlacaProductions   Rats. Both of these were shipped to me and they w...   Aug 21 2025, 07:18 AM
FlacaProductions   Interesting - but it will make it more difficult t...   Aug 21 2025, 01:34 PM
Superhawk996   Let’s review: Fact: D-jet does not run proper...   Aug 21 2025, 02:21 PM
emerygt350   But it would run. Not well.   Aug 21 2025, 04:10 PM
Superhawk996   But it would run. Not well. Yeah the definition...   Aug 21 2025, 07:23 PM
FlacaProductions   I need to see what is actually leaking/causing the...   Aug 21 2025, 04:39 PM
Ron914   I have been fighting MPS issues with my 76 D-Jet f...   Aug 21 2025, 07:19 PM


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