CJ5 Clutch Issue

CJ5 Clutch Issue


CJ5 1979 258 I6 T150
Hi all,

I recently purchased a 79 CJ5 Jeep with a AMC 258 i6 / 4.2l engine I6. The jeep takes very little to get started and idles well. However, once you push in the clutch and shift into a gear things get complicated. If I shift the jeep into gear and let off the clutch the engine dies every time. The engine seems to flood and will not restart until an hour later. I have to give it quite a lot of gas to keep it running. It does not matter what gear I shift into. As soon as I let off the clutch it wants to die. If I keep the clutch pushed in some and give it quite a bit of gas the jeep will start to move. I know riding the jeep with the clutch pushed in some will damage it over time. So what I need to know is why the jeep wants to die when I let the clutch out and how can I fix this problem.

So as soon as any load is put on the motor it does this?

I think it is vac leak related or fuel delivery related, but to be sure, what i would do (I'm not an expert by any means) is jack rear wheels off the ground, and block front tires (in reverse order) and then try to put it in gear with no real "load" on it. If tires spin, and no bad noises, I think the mechanics are all good (clutch, throughout bearing etc) and tranny etc is good...

Then you can start trying to verify where your vac leak is...

What have you done (if anything) or has been done to this motor thus far? Any upgrades or swapping of components we should know?


~ JR
So many things to look at. Start with the obvious and go from there. Is your parking brake cable broken with the parking brake stuck on? You can rev the engine so it seems the fuel pump is working and the vacuum lines should be in place. We need a lot more information I think. You said it was a recent purchase. Has it ever worked for you? If so, when did it start not working? Have you changed anything? I would lift all the tires off the ground, one at a time and see if they spin freely. From what I have heard, I do not think it is a clutch or engine issue.

Will it roll if you push it in neutral?

Sounds like a stuck caliper or locked up drum.

Best to jack up the wheels and see.
Hey JR74CJ5

I can put some load on it but I must keep the clutch pushed in some. If I let the clutch all the way out it dies, even if I'm not moving. I agree with the vac lines and fuel delivery related ideals. I see some of the vac lines have been caped off. How can I find out where each line should be connected? Is there any particular way you recommend testing the remaining vac lines? I've heard of several ways to do this and was just wandering what method would be the best. The fuel is currently coming from a gas tank inside the cab of the jeep. This was something the PO put together due to the fuel line being blocked by rust from the fuel tank. Could the engine be getting to much fuel from this tank? A friend recommends I put a fuel regulator on the line between the tank and engine. Do you feel this would help? I will try your ideal of testing the jeep while it is off its wheels. I just got the jeep and have not made any changes so far. I have put some oil in the engine and used some carb cleaner. It appears some oil has been leaking from the oil pan. Changes the PO reported and that I can find include: new battery, new fuel pump, new distributor cap, new spark plugs and rebuilt carb.

Hey Tommy

Yes, my parking brake doesn't work. How can I tell if the brake is stock on? I used my friend's truck to pull the jeep yesterday with no problem. Maybe the brake in on but just not holding like it should. Yes, I can rev the engine and let it idle with no problem. It has always idled well but has never moved without holding the clutch in some. The last PO reported he drove the jeep about 5 months ago with no problem. However, I find that hard to believe with the way it's running now. I have not changed anything besides putting some oil and carb cleaner in it. I'm very happy to hear you feel it's not a clutch or engine issue. I like your ideal of testing each wheel to see if they spin freely. RJ74CJ5 also recommended this test as well. I will give this a try and let you both know how it turns out.

Hey 73 CJ

Yes, the jeep will move in neutral. I agree with testing each wheel to see if it will move freely.
There could be so many things causing this...from a bound up drivetrain, anything from the clutch to the brakes, to an engine issue under load such as bad timing, carb and fuel delivery problems, etc...eliminate one thing at a time starting with your drivetrain.
I put the jeep up on jack stands today and tested the wheels. After some inspection I found that the E brake was damaged and it had been engaged. I got the E brake disengaged and now the wheels turn much easier and I can drive the jeep with the clutch all the way out. I feel crazy for not thinking of that sooner. Thanks Tommy for the ideal.

So now after getting to run the jeep for a bit I've started looking for other things that maybe broken. I see that some of the vac lines are not connected. Does anyone have the vac line diagram for a 1979 CJ5 ?

Also thanks to everyone for all your recommendations.

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