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djjakubik 10-25-2013 12:08 PM

Acceleration Rattle
I searched a ton of forums prior to posting and I didn't find what I needed.

OK...I have had this Jeep for about a month and I have done a few things to make it more sound mechanically. I had a full tune up, carburetor cleaned up and a new muffler as well as a new tailpipe. I finally ran all of the gas out that was in there when I bought it and I started using the non-ethanol fuel. I just noticed a rattling / "can of marbles" sound when I accelerate. I never hear the sound when I am stationary and revving the engine or coasting out of gear and revving the engine...only when I am in gear.

Any help would be greatly appreciated!

walkerhoundvm 10-25-2013 12:13 PM

Either your timing is off or you have an exhaust leak close to the manifold. Both of those are easy and nearly free to check.

djjakubik 10-25-2013 12:28 PM

I didn't hear it prior to them messing with the exhaust system. I know for a fact it wasn't there. I will bring it by the exhaust shop and get them to inspect that rattle.

Another thing...I also noticed a constant noise in what seems to be the front left wheel well after they installed the new exhaust parts. The wheel well noise was there prior to the exhaust work, but never constant. Now the noise is gets faster when I accelerate, it's always there whether I am in or out of gear, speeding up or slowing down and when I apply the brakes. I don't know how to describe it. It is not grinding...not squealing...not humming...not knocking or rattling. Just a constant sound...

djjakubik 10-25-2013 12:31 PM

Walker...I am definitely not a mechanic. With regards to the timing, would that be something they did not do correctly when they were messing with the carburetor?

I have taken it to two different shops here in town. Local long time mechanic and a exhaust shop...not the same shop doing the work.

walkerhoundvm 10-25-2013 12:51 PM

It could be something they did, but chances are, if it's timing, it's something they didn't do. My guess would be if they rebuilt the carb or tuned it, they didn't bother with the might just need an adjustment after you've now got the carb sorted out. After which the carb may take some more fine-tuning ;)

As far as your front wheel - could be anything associated with that wheel: bearings, hub, ball joints. If you lift the front end of the vehicle up and grab the wheel, it shouldn't have much if any side to side or top to bottom movement. Side to side implies bearings, top to bottom implies ball joints. With a 30y/o vehicle, it may be worth it to just service the whole assembly left and right...about a $6-800 if you do it yourself.

djjakubik 10-25-2013 01:59 PM

I am not exactly sure what they did to the carburetor. He said it was pretty clean when he went in and he "adjusted" it. I am at the muffler shop now about the rattle...I'll let you know how it turns out.

The other guys are supposed to be replacing the front bearings and ball joints. Hopefully it will solve that issue...

hutch1200 10-25-2013 05:18 PM

1) When accelerating the engine will tilt to the side ever so slightly. It will not move as much revving in neutral, or any other time you're experimenting. When they ran the exhaust, and it is tight under there, the pipe seems to be just barely hitting on something. Accelerating under load, rotates the engine to the side, in relation to the crank centerline, and the noise is intensified.
2) When they lifted the CJ at the shop, they likely unloaded the suspension for the 1st time since it last got tires. So, yeah, might be time for a front end service. Especially if it sat awhile.
Good luck! Let us know how you make out....w/pics too.

djjakubik 10-28-2013 09:17 AM

The exhaust shop said they had no idea what was making the noise. They lifted it up and checked the things they installed and everything seemed to be ok. I know that the technician didn't hear the noise I was referring to when he drove the Jeep. I didn't have time to take him on a ride and show him the noise I was referring to after waiting an hour and a half. I am going to bring it back to my other guys and let them listen to it while I am driving, so I can be sure to recreate the noise for them.

hutch1200 10-29-2013 03:49 AM

Have you checked for wear/dry rot/tightness in the motor mounts? This goes back to my engine movement theory.

djjakubik 10-29-2013 10:42 AM

Hutch...One of my transmission mounts is loose. Can that be the culprit? I believe the engine mounts are pretty solid.

Tigerjeep79 10-29-2013 11:23 AM

The noise you describe sounds like the ignition timing is too advanced. It's called detonation, and it's really bad for your engine. If you don't have a timing light, loosen the hold-down bolt at the bottom of the distributor (just a little) and turn the distributor clockwise (again, just a little). See if that helps. If need be, do it again until the noise goes away. Afterwards you'll need to adjust your idle speed, which is very easy to do.

You really should get a Haynes or Chilton's manual. It'll save you lots of money.

walkerhoundvm 10-29-2013 11:24 AM

I'm going to guess it's your torque arm busing and assembly, and if that's the case it's supposed to be a little loose.

hutch1200 10-29-2013 10:46 PM

TigerJeep79 may be on to something . Since you free'd up the exhaust, de-gunked the carb etc...You may be getting "pre-ignition". Try a higher octane gas and see what happens. Maybe throw a can of octane boost + higher octane and see if it goes away. If it does go away, you'll need a timing light.
PO might have been making power during the sale?

djjakubik 10-30-2013 08:40 AM

The local shop I have been using said that I needed to use non-ethanol fuel due to the age of the vehicle. Are they right or should I use and ethanol / higher grade fuel? I do not remember the noise happening prior to using the non-ethanol fuel. But, it could be a coincidence that the noise occured once I switched. The vehicle is 30 years old.

Tigerjeep79 10-30-2013 12:51 PM

Many of us don't have the option to run non-ethanol fuel. I've been running Shell premium in my '79 for years with no apparent problem. Of course, I've replaced all fuel hoses from engine to tank. Someone may correct me here, but I've been under the impression that ethanol rots old fuel hose pretty quickly, and the newer compounds hold up better.

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