Trying to get an idea on the life expectancy of the MPS. I know, probably all over the map. Does anyone have an opinion on how this is effected by lack of use (my car sat for over a decade)?

Is this pure curiosity or are you trying to determine if yours is still good or not? If in question, just test it. Pull a vacuum on it. If it holds, you should be good (assuming the electrical is still good). If not, source one or buy the repair kit from Tangerine. It's not hard to fix.

My MPS is bad and I'm looking to get a good used one. But I'd like to first get a clearer picture of how long-lived they are. Do they routinely go over 100K miles? 150K miles? Just want to know what members have experienced with their cars.

I'm aware of the Tangerine kit, but to be honest, I have too many other things to fix on this car at the moment.

My impression is that they weaken with age and use (some combination, who knows exactly) and then fail catastrophically due to some event (e.g., backfire) that puts sudden pressure on the diaphragm. I would hesitate to guess how many D-Jet cars are running well with their original MPS at this point or how long it will last in terms of mileage. Anyway, a used MPS for sale doesn't have an odometer, so you can only truly know how old it is, not how hard it's been ridden. To me your options seem to be:

1. Find a NOS MPS = $$$
2. Buy a functioning used MPS that could last a week or another few years - sometimes you can get a good deal on one.
3. Repair yours with the kit. $150 plus about 2 hours of time.

Maybe Jeff Bowlsby or someone has "data" on when these typically started failing (age / mileage timeframe).

Yeah, I know this is a difficult question to get an answer to. If enough members chime in, though, it might be possible to get an idea.

I'm sure the kit is great, but I just have too many other things to tackle and my mechanical skills are lacking.

I suppose the fourth option is buy one someone has already repaired.

142,000 miles, original 1970, still good. I bought Bowlsby's kit for back up, it is still sitting on the shelf.

FIFY

Those of us who have been around awhile realize what a tremendous thing Chris's replacement MPS diaphragms are. There was a time not long ago when no new diaphragms were available, only old used MPS's of unknown condition. I cannot tell you how many MPS's I have taken apart, that even thought they held vacuum, also had a cracked diaphragm. Chris single-handedly saved D-Jet 914s.

I rebuild and calibrate the MPS using Chris's diaphragms and try to keep a stock of them available at all times.

Details on my website: http://bowlsby.net/914/WiringHarnesses/

Sorry Chris. Ich haben upgefuched again.

Agreed. The fact that he was able to reproduce these was impressive. Truly a gift to the DJet community. Other DJet parts aren't vital or are readily available new or used.

And, he is not a total ass about it.....just a cool vendor