Broken vacuum lines

[EODBuddyLee]

My CJ has been running a little rough lately, so I started trouble shooting and looking around. Its a rough idle and surging so I started looking through the vacuum system to see if I could identify any leaks. I found two good ones. They are corroded clean through and not attached. I have searched just about every page of the Chiltons Manual with no luck finding what part I need to order. I have also been looking all over the internet with no luck as well. Attached are pictures of the 2 lines that are in question. Any help would be much appreciated.

The carb doesn't have a tag but everything I have seen looks like the carb is a Motor Craft 2100 and the engine is a AMC 304 if that helps.

Cheers

 

[dunebuggy18]

The joys of living on Maui! Great place to be, but tough on the old Jeep... .

Check you this link: http://www.jeep-cj.com/forums/f7/vacuum-diagram-5051/

It has a copy of the vaccum diagram for your jeep.

 

[dunebuggy18]

I believe that it is the TAC (Thermostatic Air Cleaner) connection - basically using the manifold vaccuum to control a door in the air cleaner to keep the intake air warmer during cold starts (wait, do you have cold starts in Maui??? )

I am not sure why there are two lines, can you post a pic of where the other line goes? Maybe for the air canister? I am sure some one knows...

 

[Jimbos76cj]

That goes to your choke to circulate hot air around the filament to keep it open. If your using an electric choke you can remove it from the system and block off the opening in the intake. Or leave the broken peice in the intake, I don't think it's open on the other end just a loop of piping that gets warmed up by the same port that the egr pulls from. With out it being hooked up you will now have a vacuum leak in you choke. If you undo the 3 screws that hold your choke on one leg has a gasket and hole. Plug that hole and cap the other line that is left open from the second pipe.

 

[Jimbos76cj]

The port that comes from the top of the carb pulls in fresh filtered air through the filter, then it passes through that loop in the exhaust port then enters the choke. Realy basic system.

 

[Jimbos76cj]

Sorry one last thought. IF you plan on replacing that part you can just cap off the port that goes into the choke until you get it replaced. I would also cap the one that goes to the top of the carb.. that one wont cause a vacuum leak but will allow unfitlered air to be drawn into the carb.

 

[EODBuddyLee]

Thanks for the replys. I will plug both of them for now and see if that works. Do both these lines have names? They are both going to the same bracket on the intake and then back up to the carb. I cannot find an IPB or parts list that show these two lines.

Again thank for the replys, hopefully the plugs will work for now.

Cheers

 

[Jimbos76cj]

See post #5? I'm not sure of the name. That bracket holds a u shaped peice of pipe into the exhaust cross over port.. You may be able to track down a wagoneer with a 360 in a scrap yard and take the one off it. It's stock equipment on most AMC 304 , 360 and I think 401. If not you can leave the "bracket attached" as long as its not leaking exhaust. It has to vacuum going to it. Ill be in the shop on Wednesday and ill see if I can find one that's already removed and post a pic of it.

 

[Jimbos76cj]

amc 360 choke heater tube broken? - JeepForum.com

Thermal choke tube.

 

[EODBuddyLee]

NICE!!!!

Thank you. I will try and find a parts jeep out here if at all possible. I do know where a couple of junked out wagoneer's are, I will see if I can find one there. If not, I will just try and cap these off. Is there any long term harm by capping them off and being done with it?

Thanks again

 

[Jimbos76cj]

No long term problems that I know about. Every one that does the 2100 upgrade to thier AMC 258 i6 / 4.2l caps theirs off.

 

[EODBuddyLee]

Thanks again. I will let you know how it works out once I cap these off.

Cheers

 

[IOPort51]

Do those holes actually suck air??

Spray a little choke cleaner around with the engine running to see where the vacuum leak is.

I do not think you have found what you are looking for.

 

[Jimbos76cj]

Do those holes actually suck air??

Yes.. the one from the choke to the intake sucks air. The one from the top of the carb to the loop does not in a way to cause a vacuum leak but it does draw air in that is unfiltered.

Spray a little choke cleaner around with the engine running to see where the vacuum leak is.

I do not think you have found what you are looking for.

beings its a jeep with what looks like all the stock still attached I agree that he has not found all of what hes looking for but atleast found 1 leak.

 

[EODBuddyLee]

You guys are right, this jeep is pretty much bone stock and I too believe there will be more to come. I plan on buying a bunch of vacuum line and just start replacing all of them instead of chasing them around. I don't have emissions out here in Hawaii, so is there a way to eliminate most of these vacuum lines for the AMC 304 ...similar to the Nutter Bypass?

 

[IOPort51]

I always recomend that you discover what they do before eliminating them. things like the EGR, TAC and distributor advance are a big plus.

 

[Jimbos76cj]

I always recomend that you discover what they do before eliminating them. things like the EGR, TAC and distributor advance are a big plus.

If your running a 2100 in your set up how do you have yours plumbed into the system?

 

[IOPort51]

If this question is for me, you will have to be a bit more specific as to what "system" you are talking about.

I will say that there are two kinds of vacuum, ported and manifold. Ported happens above the throttle plates and manifold happens below. The big difference shows up when you open the throttle. the ported goes from low to high vaccum and the manifold goes from high to low. Manifold vacuum is real good for things like power brakes, PCV connections and the thermostatic air cleaner. the ported vacuum, although some will argue the validity of this, is good for things like the distributor and the EGR valve, things that you want to "work" at acceleration or under load.

Hoping not to confuse things too much, there is the CT (coolant temperature ) switch that turns some things off (TAC) and some things on(Pulse air, EGR and distributor advance) when the engine warms up.

Is everybody with me so far??

If your running a 2100 in your set up how do you have yours plumbed into the system?

 

[Jimbos76cj]

The opening on your choke on your 2100.. How did you block yours? All that line does is use a little bit of vacuum to pull clean air from inside of the air cleaner assembly through the loop of tubing that is inside your exhaust stream in the stock AMC 304 /360 intake. For what ever reason it was built into the choke system to pull warm air around the choke element. With having a electric choke you do not need that extra peice. Any one running a 2100 on a AMC 258 i6 / 4.2l has one way of another had that port blocked, plugged, epoxied, or other wise made so vacuum will not get pulled through the choke port. If yours on your 2100 is not plugged the. You have a vacuum leak in your carb. Unless you managed a way to properly set it up to pull hot air through your manifold on your AMC 258 i6 / 4.2l .

If has not effect on any other vacuum driven system in your engine compartment.

 

[IOPort51]

I think you may find that the air goes the other way. the low pressure in the air breather draws warm air through the choke from a mount on the exhaust manifold. . I don't think this is actually in the "vacuum system at all.

I did not fill or plug anything, the header had no place for the end to mount and the 7" air cleaner I am using to clear the brake booster has no port for the other end. I have found that just having the tube in the vicinity of the exhaust manifold warms the choke up pretty well and I do not use the electric choke.