thetundrawolf

Hello,

I have a 1982 Toyota pickup with the 22R engine. The distributor has a vaccuum advance that looks like a dual- diaphragm type.

I apply vacuum to the upper (outer) vaccuum connection and it holds vaccuum. I apply vaccuum to the lower (Closer to the distributor housing) vaccuum connection and it does not hold vaccuum at all. Is that the way it's supposed to work, (With a little leakage for the secondary diaphragm?) or are both supposed to hold vaccuum?

naylor2009

I have an 83 with that same vacuum advance. I'm not sure how it works but when I apply vacuum to the top one it seems to do nothing but when I apply vacuum to the bottom one at high rmp it moves to an open position.I know this probable didn't help but I'm trying to figure out if this is the way it works.

thetundrawolf

No, they should both hold air. I did some research. A new vaccum diaphragm mechanism is $140! The cheapest I found was $130!! That's insane! So, I am re- building it. (The bottom one, anyway. Same procedure for the top.) I'll do an 'able and post the link here if it works out, or even if it doesn't, maybe someone can figure it out.

What i did was,

I opened the crimp seal a little with a small chisel, then opened it up the rest of the way with a pair of piers.

I separated the bell housing, and then used brake cleaner (not brake fluid) to dissolve all of the rubber in the diaphragm. This took a while, around twenty minutes, and the use of a blow gun when the mesh was saturated with brake cleaner helped to totlaly clean it out.

I then coated the diaphragm mesh with silicone gasket maker, but I pushed the silicone through the mesh, so make sure it bonded really well.

I sealed both sealing surfaces with silicone, let it cure a little, then re- assembled it.

Turns out the silicone will pull the diaphragm inward as it cures, so I took it back apart, and re- coated some damaged areas with the silicone.

Right now it's layin on the desk next to me.

What I plan on doing is, since it's dry, now, is to put daubs of super glue on strategic areas around the sealing surfaces to "hold" the diaphragm in place so I can re- assemble it.

Before I re- crimped the pieces together the first time, i sucked on it and it held vaccuum, so I know this will work.

Better details and pictures coming in the 'able.

kawazx636

iTrader: (3)

If you are going to replace the distributor, try going to Advance Auto Parts' website. I got a whole distributor there for $98. Then about an extra $20 or so for a new cap and rotor, if needed. Do a Google search for coupon codes and you'll likely find at least a 20% off coupon - they always have some sort of coupon code promotion going on. By the sound of it, your "fix" seems to be just that. I wouldn't count on it lasting very long. The leak in your inner vacuum advance will cause you difficulties when trying to get your timing right at idle which in turn will affect your timing at higher RPMs which can have a considerable affect on MPG and overall performance. You'll probably end up paying for that distributor that you didn't buy via fuel economy or other more serious issues that can come from poor timing. You'll thank yourself later for making the investment.

enigmaT120

These guys sell the vacuum advance unit, though they lost one supplyer and had to find another (for more money):

http://www.lceperformance.com/Distri...-p/1081123.htm

Are there two diaphrams in that thing, with one between the two vacuum inlets? Or do they both pull on the same diaphram, but at different times?

I'm not sure what Naylor meant by it going "open". When vaccum is applied to them they should advance the timing. One advanced it more than the other, when I tested my new one. Now it doesn't seem to be working, but I think I have vacuum leaks somewhere so I have to spend some time trouble shooting.

If your vacuum advance doesn't work and you want to drive anyway, just cap both of the vacuum sources and set the timing advanced until it runs well. I guess mpg will suffer, but it should get you around until you can get it fixed. Just make sure it doesn't ping when you take off.

thetundrawolf

I'm making it so that there is no "leak" anymore. The silicone is actually stronger than the soluable rubber they had impregnating the structural fibrous mesh in the vaccuum diaphragm.

If I had $100 I'd buy the new distributor.

thetundrawolf

There are two physical but independant vaccum diaphragms inside the unit. One on top, one on bottom. They both do the exact same thing. When vaccuum is applied to the top tube, the advance lever moves all the way in against a stop. I believe the lower diaphragm will do the same thing.

I'm not immediatly aware of any such a setup is required to isolate two separate vaccuum circuits to accomplish the same task.

The only issue that could result from my "fix" is the possibility that it might not fully retract because the silicone has added extra thickness to the diaphragm. However, the more I study it, the more I realize it will work fine.

I am also becoming aware of re-assembly techniques that I need to perform to make it more durable. This is why I do these things, to learn how to fix things people would ordinarily throw away.

For me, $130 is thirteen hours of work to earn that much money. If I can satisfactorily repair it for two hours of work, then I am going to do that, while educating myself and others in the process.

enigmaT120

Can you let us know how you crimp the parts back together?

thetundrawolf

Yes you can be assured I will. I made a mistake crimping it the first time which is why I am having to do it over again.

I have a lot on my plate right now, so it has to take a back burner for now.

HighLux

Funny thing...autozone shows advance unit for 124. Then shows new ditributor with advance unit on it for 104. Go figure.

These are pretty common failure. My trekker records show previous owner had toyota replace 3 times.