I'm in the process of rebuilding my Disty, its vacuum advance wasn't working. The "breaker plate" was all rusted up and the plastic ball bearing holder was broken. But thats a different story. What I want to know is how tight are these diaphragm suppose to be? Can you make them move with your mouth? My Manual says you are suppose to be able to make it move by sucking on the diaphragm inlet.

But mine is tight, it does move, but not with me sucking on the inlet.

if it does not move, or moves then moves back to the original position then the diaphragm is bad.

The diaphragm isn't leaking vacuum, it will hold a vacuum quite happily. Just it doesn't move under my suction like the manual says it is suppose too.

It springs back fine as well. I just can only move it with my fingers, because its tight.

so you can move with your fingers, but not when you suck on it?

 

it should move freely, nearly no force at all, if there is replace it.

I'm in the process of rebuilding my Disty, its vacuum advance wasn't working. The "breaker plate" was all rusted up and the plastic ball bearing holder was broken. But thats a different story. What I want to know is how tight are these diaphragm suppose to be? Can you make them move with your mouth? My Manual says you are suppose to be able to make it move by sucking on the diaphragm inlet.

But mine is tight, it does move, but not with me sucking on the inlet.

Hitachi or ND? If it's Hitachi, the entire thing can be disassembled quite easily. If I remember correctly, the lower plate runs on ball bearings. If that's rusted or one of the balls is out of the channel, it'll bind up. Sorry, it's been too long since I've had one apart so far.

Hitachi I believe I've already stripped it down and found the breaker plate was rusted up and the plastic that holds the balls is broken, going to need a new breaker plate.

 

But my question isn't related to that, I shouldn't of mentioned it. I'm just asking about the vacuum diaphragm.

I would replace the diaphram, if for no other reason than just to be safe and know you have a good one on there.

-Bill

That is assuming I can get new parts for this old thing... I'll find out tomorrow (monday)

If you can't move it by sucking on it - it's bad. It needs to be able to respond quickly to small changes in manifold vacuum - just a few inches of mercury. You should be able to suck about 5 or 6 inches and it should be responding to that. Max vacuum signal to the pot is around 20 inches or less due to the ported vacuum design and the limits of what the engine can pull.

 

Likely the rubber inside has shrunk or something. There are places that can rebuild them. I had one done a coupe years ago for about $20. As they are no longer availible that seemed like a good way to go.

 

GD

^ thanks GD, thats what I was after. I knew you'd be able to answer this one. Probably should of just PM'ed you.

 

I can't get the breaker plate, and the vacuum advance diaphragm will cost $95AUD. This is too much. The guy at the auto parts shop has an EA82 though, and it may have a pointless disty. In which case I'll be converting to EA82 disty on my dual carb EA81 to keep me going. Hopefully EA82's didn't suffer the same vacuum advance problems.....

 

 

See new post about disty conversion http://www.ultimatesubaru.org/forum/showthread.php?p=785523#post785523

Edited January 12, 200917 yr by Phizinza

Hitachi I believe I've already stripped it down and found the breaker plate was rusted up and the plastic that holds the balls is broken, going to need a new breaker plate.

 

But my question isn't related to that, I shouldn't of mentioned it. I'm just asking about the vacuum diaphragm.

The metal arm that goes out to the diaphragm has a spring around it. If the arm is binding there's probably rust inside the tube that's restricting the arm from moving easily. Either that or someone stretched to spring to make it stronger. I think I may have some of the pieces you need. If you know exactly what you need I will look into my "sprare parts bin."