79 CJ7 pops in 4WD

[clemmonds]

Question from a newbie here... When I lock hubs & engage 4WD, I get a loud pop/bang when driving. It is not in a rhythm that sounds like it is in the normal rotation but can't seem to figure out a fix.

Any ideas from some of you more experienced owners?

 

[Tyler Bates]

have you checked your u-joints on the front driveline, does it do it in just 4 hi or 4 lo or both because could be in your t-case

 

[Saddle Tramp]

When you lock in the hubs are you on pavement or dirt? Maybe you have a luch box locker in the pumpkin. If on pavement steering will be hard to keep under control, on dirt not so bad.

 

[sweetpeet]

Question from a newbie here... When I lock hubs & engage 4WD, I get a loud pop/bang when driving. It is not in a rhythm that sounds like it is in the normal rotation but can't seem to figure out a fix.

Any ideas from some of you more experienced owners?

Can you tell exactly where the pop/bang is coming from and is it repetitive or does it just happen right after engaging 4wd?

 

[clemmonds]

Can you tell exactly where the pop/bang is coming from and is it repetitive or does it just happen right after engaging 4wd?

It is repetitive but not in a synchronized time... if that makes sense. It bangs sporadically and not in rhythm.

 

[clemmonds]

have you checked your u-joints on the front driveline, does it do it in just 4 hi or 4 lo or both because could be in your t-case

Both. The u-joints seem fine I think.

 

[clemmonds]

When you lock in the hubs are you on pavement or dirt? Maybe you have a luch box locker in the pumpkin. If on pavement steering will be hard to keep under control, on dirt not so bad.

That could be it... not 100% sure but I am going to check this as well. From what I have read, this could be it. Again, Proby here... not 100% sure.

 

[sweetpeet]

Ok, we really gotta know exactly where it's coming from because different parts mean different problems.

if you don't think it's coming from any where below you( like the t-case) then that's good. If the hub lockers are old then they prob need a new kit put in. Chances are that 1. There is dirt in there 2. The rings are falling apart. To me it sounds like number 2. To check the hubs you'll need to pull them out, any damage will be obvious. Should be easy to pull them out.


Oh, one more thought! Are you sure it's not more of a rumble????

 

[Saddle Tramp]

Just another thought but when the bearings inside the diff go out you will get some clanking but at first I have found it to be more hit and miss.

 

[Tyler Bates]

Im not sure if this would tell you anything but you can lock the hubs and drive without putting in 4 wheel so that might tell you more about the hubs??????

 

[clemmonds]

Definitely not a rumble.

 

[clemmonds]

Thanks all here... I am checking it as soon as I can. I have another fix... I think the fuel pump is clogged or something. It started sputtering this morning and wouldn't stay cranked. This is how you learn right???

 

[Saddle Tramp]

On a 1979 CJ the fuel pump is mechanical and rarely will become clogged, but will go bad. Typically if bad the diaphragm inside the pump is shot. It is possible for a pump to run for a bit then stop, a bit later they can work for a while then die again. Eventually they just stop working forever.

The fuel filter on the other hand will become clogged with time and may be the problem but it also could be a vacuum leak too. Check the engine and make sure everything is tight.

 

[clemmonds]

Yes. I thought about it being the fuel filter after reading some where that filling the tank would cause that to happen. I don't think the Jeep had been driven in a year or more when I bought it so I expected a few things like this.

Thanks again... these forums a really helpful.