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paskalee

vacuum reservoir for 1986 MJ

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My Comanche is a 1986 with a 2.5L. My vacuum reservoir is broken; it has a couple of large holes in it. I can not find a replacement to it, the mopar part number i found is: J3232991. But I cannot find it anywhere. The new replacement reservoir's I have found only fit 1991 and up models. Can someone tell me if these will also work on mine? They seem to have only one connection to them while my factory reservoir has two lines running to it but has two connections on each side of the reservoir. And of course by air in the vehicle is only blowing through my defrost vents and I am sure the broken reservoir is the cause.

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all canisters operate the same.  try the junk yard first, good chance you can get a mint one for $5 or less.  I believe all renix era 1986-90 had dual fitting canisters. but even if you can only find a single canister. you can buy the hose and T splice for probably $3 at napa

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all canisters operate the same.  try the junk yard first, good chance you can get a mint one for $5 or less.  I believe all renix era 1986-90 had dual fitting canisters. but even if you can only find a single canister. you can buy the hose and T splice for probably $3 at napa

They could go either way as to large or small. Other makes used the same stuff. 

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Thank you guys. Unfortunately, the nearest junkyard by where I live is a two hour drive so I will just have to look at parts stores or online

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The newer Jeep canister (53030500) should work for you if you rework your vacuum lines and hook it up like the diagram below. It should also fit in the same spot as your old one but you will need to fab up a bracket for it.
 
 

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Yes, I am looking for the vacuum canister that is behind the passenger side bumper. Is the 4WD system not affected by the reservoir? The 4WD seems to work still, it is just that air will only blow through the defrost vent.  

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Yes, I am looking for the vacuum canister that is behind the passenger side bumper. Is the 4WD system not affected by the reservoir? The 4WD seems to work still, it is just that air will only blow through the defrost vent.  

The 4wd system can be affected if you have a CAD front axle and you haven't bypassed it yet. 

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My 2000 XJ (fully loaded Classic) and my 1988 MJ (SporTruck) had the exact same canisters stock from the factory ... The smaller ball canister. Different part numbers but the same cannister.

I parted an XJ that had the larger football, it was a fairly fully loaded Laredo.

Pretty much any cannister will work, it's mainly just there to store vacuum so the controls will still function correctly at times of low vacuum (WOT, Engine shut down, etc...).

I'd send you one of my spares, but shipping costs from up here are more than the part is worth.

 

Sent from my SGH-I337M using Tapatalk

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I've often thought that a good, durable vacuum canister could be made out of standard propane torch tank. They already have an opening at the top, you just have to make up an adapter to connect the vacuum tubing to.

 

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Or an old disposable fire extinguisher ... They are 1/2" NPT threaded in general and easily converted.

 

Sent from my SGH-I337M using Tapatalk

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So, correct me if I'm wrong...the vacuum reservoir is not subjected to a HUGE amount of pressure and the interior of the reservoir is just space.  I don't think there are baffles or any moving parts inside.  So it seems to me you could use a piece of ABS/PVC pipe...3-4" diameter and a cap glued on each end, with some brass (?) fittings for the vac hoses.  That way you could customize the size, location etc.  And it'd just be a trip to the hardware store...or am I missing some mystery of the internals of the reservoir.  I've never cut one open.

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So, correct me if I'm wrong...the vacuum reservoir is not subjected to a HUGE amount of pressure and the interior of the reservoir is just space.  I don't think there are baffles or any moving parts inside.  So it seems to me you could use a piece of ABS/PVC pipe...3-4" diameter and a cap glued on each end, with some brass (?) fittings for the vac hoses.  That way you could customize the size, location etc.  And it'd just be a trip to the hardware store...or am I missing some mystery of the internals of the reservoir.  I've never cut one open.

I'm not sure. I always thought there was a diaphragm inside/valve/ or something. 

I don't have any small ones to destroy, only the football sized ones.

 

Did you get my emails?> 

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So, correct me if I'm wrong...the vacuum reservoir is not subjected to a HUGE amount of pressure and the interior of the reservoir is just space.  I don't think there are baffles or any moving parts inside.  So it seems to me you could use a piece of ABS/PVC pipe...3-4" diameter and a cap glued on each end, with some brass (?) fittings for the vac hoses.  That way you could customize the size, location etc.  And it'd just be a trip to the hardware store...or am I missing some mystery of the internals of the reservoir.  I've never cut one open.

I'm not sure. I always thought there was a diaphragm inside/valve/ or something. 

I don't have any small ones to destroy, only the football sized ones.

 

Did you get my emails?> 

 

 

I don't know either. Never took one apart. I always assumed (which I know is dangerous) that the ones with two ports must have a partition inside to create two chambers. Otherwise, they wouldn't need two ports, they could have run one line to the canister and teed it off where they needed the second line.

 

I'm pretty sure there isn't a check valve. After all, the flow has to go both ways. There might be a restrictor in the orifice(s) to prevent the vacuum from getting used up too fast, but that's just a guess. I think if you're making your own replacement, bigger is better (until weight becomes an issue).

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But as I thought about it some more...there might/should be a check valve inside to HOLD the vacuum...it seems.  Which, even in a coffee can could be easily added.

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Do I need to sacrifice a football one? 

Absolutely! 

 

In the name of science, I will. 

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Here ya go. It's just a sealed reservoir with a one way check valve inside on the vacuum SOURCE side.

 

FWIW, I cut open one of those metal cans and there's a built-in check valve for the vacuum source. 

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Good 'science'  Now one could still use the other side of the football, send it to me, I'll trim it and make it a zero clearance ball up against my firewall.  My e-mail is broken though. 

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Good 'science'  Now one could still use the other side of the football, send it to me, I'll trim it and make it a zero clearance ball up against my firewall.  My e-mail is broken though. 

Haha. That's what I did for MY MJ!! 

 

I can only make 1 out of one. I think....I'd make you one. 

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Here ya go. It's just a sealed reservoir with a one way check valve inside on the vacuum SOURCE side.

 

 

Do you have any way of figuring out how the check valve works? Would it be possible to duplicate it (functionally, at least) in a home-brew unit?

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