I am new to the Jeep community. I just came across a CJ for a good price, I think. My question, as with all older vehicles, things need to be done. I am missing all vacuum lines. Which are of importance right now? Also, I have a heavy exhaust smell coming into the cab. I am pondering taking the CJ to an exhaust/muffler shop. After reading some posts, there are some knowledgeable jeepers out there. Any advice would be greatly appreciated. Thanks.
1980 CJ7 Vacuum Lines
- Thread starter JakeNM
- Start date
Crazy4diesels
New member
Hi JakeNM,
I would say the distributor advance line is most important for driveability. It probably went from the intake source to a temperature controlled valve and then on to the distributor. Without this line you won't get the right advance curve and the engine will not perform at all. Look for a diagram under the hood (I'm not sure if the 80 model had it but probably). This will show all of the vacuum line routing. A Chilton manual would also have the diagram. On that year you would probably have a combination valve that controlls the air pump output (looks about like a coke can in size). This is controlled by several vacuum lines (not too important unless required by your emissions laws). You will have the EGR circuit which has a temperature controlled valve and vacuum lines. This is not needed unless you have emission laws that require it to be working - although, a properly working EGR valve can help keep the engine from pinging, if I recall. On the air cleaner housing you should have a vacuum operated door that directs hot/cool air to the carb. This system has several lines and a thrmostatic valve. Not too important unless you get carburetor icing... Hope this helps a little. CJ's are cool - Best of luck - John
I would say the distributor advance line is most important for driveability. It probably went from the intake source to a temperature controlled valve and then on to the distributor. Without this line you won't get the right advance curve and the engine will not perform at all. Look for a diagram under the hood (I'm not sure if the 80 model had it but probably). This will show all of the vacuum line routing. A Chilton manual would also have the diagram. On that year you would probably have a combination valve that controlls the air pump output (looks about like a coke can in size). This is controlled by several vacuum lines (not too important unless required by your emissions laws). You will have the EGR circuit which has a temperature controlled valve and vacuum lines. This is not needed unless you have emission laws that require it to be working - although, a properly working EGR valve can help keep the engine from pinging, if I recall. On the air cleaner housing you should have a vacuum operated door that directs hot/cool air to the carb. This system has several lines and a thrmostatic valve. Not too important unless you get carburetor icing... Hope this helps a little. CJ's are cool - Best of luck - John
whsmith4th
New member
I can help a little perhaps.
I have a 1981 CJ7 Renegade that also had all the vacuum lines removed and was failing emissions tests. Most Jeeps of this era used a combination of valves for controlling vacuum advance and turning on the Exhaust Gas Recirculation (EGR) valve. There were a few various configurations for tis stuff also. The basics though are that you have a CTO (Coolant Temp Overide) valve that sends vacuum to the EGR when the engine coolant is hot. Just hooking this up and having your vacuum advance connected from the carburetor vacuum port to the input port of the CTO will probably get you past the emissions tests and keep your Jeep running quite smoothly - it worked for mine here in Finland.
The most common method of circumventing the emissions controls was to hook one vacuum line from the carburetor to the distributor and throw out all the other vacuum hoses. The problem with this is that places looking to suck vacuum were sucking air and all should have been blocked off.
I do have a number of diagrams I found that apply to Jeeps like ours and I can send them to you if you'd like.
Cheers,
Will
I have a 1981 CJ7 Renegade that also had all the vacuum lines removed and was failing emissions tests. Most Jeeps of this era used a combination of valves for controlling vacuum advance and turning on the Exhaust Gas Recirculation (EGR) valve. There were a few various configurations for tis stuff also. The basics though are that you have a CTO (Coolant Temp Overide) valve that sends vacuum to the EGR when the engine coolant is hot. Just hooking this up and having your vacuum advance connected from the carburetor vacuum port to the input port of the CTO will probably get you past the emissions tests and keep your Jeep running quite smoothly - it worked for mine here in Finland.
The most common method of circumventing the emissions controls was to hook one vacuum line from the carburetor to the distributor and throw out all the other vacuum hoses. The problem with this is that places looking to suck vacuum were sucking air and all should have been blocked off.
I do have a number of diagrams I found that apply to Jeeps like ours and I can send them to you if you'd like.
Cheers,
Will
iraq_vet_x2
New member
Jake, take a look at this website...it'll get you spun up on what's important and what's not. It'll also give you a vacuum line schematic, which has come in real handy for me on several occasions.
Table of Contents
Good luck....
Table of Contents
Good luck....
whsmith4th
New member
My Haynes manual has part of what you're looking for. The problem I have found is that AMC (and most car companies during the late 70's and early 80's) were mucking around with a variety of different configurations. Keeping it simple is the best advice I can give you. Not only are you missing the vacuum hoses, but there are a few check valves and delay valves that were installed in the vacuum lines. These are also missing. I kept it simple for my V8 and it has worked fine. Hook up your EGR valve, your Distributor vacuum and your CTO valve - that will be enough. Any other vacuum port that is sucking air - block it off. If you don't have a vacuum guage, get one and hook it up to every vacuum port you can find and check if that port sucks air - do this when the engine is cold and when it is hot. There are a couple valves (depending on what is actually installed on your engine) that will change based on engine/coolant temp. These are the CTO (coolant temp overide) and the TVS (thermal vacuum switch). The TVS is on the air cleaner and the CTO is mounted in the coolant channel near the thermostat housing. There are 3 types of CTO switches I have found - one has 2 ports and one has 3 ports and one has 5 ports. You need to find out what your Jeep actually has installed in order to know what you really need to hook up.
There is also a TAC (thermo controlled ir cleaner) switch on air cleaner housing. this is used to route warm air (from the air hose connected to the manifold) into the carb when the engine is cold. This should be hooked up to vacuum if you live anywhere where it gets cold.
Once you know what you actually have on your engine, it will be much easier to tell you where you need to hook up vacuum lines. You do want to get some things hooked up since the engine will run better if you do.
There is also a TAC (thermo controlled ir cleaner) switch on air cleaner housing. this is used to route warm air (from the air hose connected to the manifold) into the carb when the engine is cold. This should be hooked up to vacuum if you live anywhere where it gets cold.
Once you know what you actually have on your engine, it will be much easier to tell you where you need to hook up vacuum lines. You do want to get some things hooked up since the engine will run better if you do.
