[jamesdeanj]

I'm new here. I have a 93 4Runner but my sister has a 84 CJ with inline 6. It has 150k and we have no idea if anyones been into the motor before she got it several years ago. It's been down for awhile but she got it running the other day, drove it home, parked it and when she started it the next day it ran really rough and had no power. We realized that the stuff inside the cat had broken apart. There seems to be allot of pressure coming out of the exhaust. How likely is it that the timing jumped a tooth?

[79cj7reny]

Since you know the cat is junk, I would start there. I assume you intend on replacing the cat, so go ahead and remove the cat, then see how it runs. Then you'll know if that was the problem.

[jamesdeanj]

I've already removed the muffler and cat. The motor seems to run smoother (the broken up pieces would jam into the back of the cat when you would start the vehicle, blocking the exhaust), but it still has that pop pop pop sound out the open pipe and what I think is to much pressure. I'm going to be putting new cat and muffler on, but I'm afraid that if the tming jumped the pressure and or added heat will damage the new parts.

[79cj7reny]

With no back pressure you're gonna get some popping out of the exhaust, until you get the new cat and muffler on. Drive the Jeep and see if it has more power than before. If not, start looking at the timing. Concentrate on one area first. Once you eliminate the blocked exhaust as a potential problem, then you can move on to another area.

[Mike Romain]

Originally Posted by jamesdeanj

I've already removed the muffler and cat. The motor seems to run smoother (the broken up pieces would jam into the back of the cat when you would start the vehicle, blocking the exhaust), but it still has that pop pop pop sound out the open pipe and what I think is to much pressure. I'm going to be putting new cat and muffler on, but I'm afraid that if the tming jumped the pressure and or added heat will damage the new parts.

The 258 engine will pop and burble really good with no exhaust on it.

Mine even pops and burbles when decelerating in gear, but I have my timing manually set up with a straight pipe exhaust to a dynomax muffler. (no cat needed on a CJ in Canada)

The timing chains normally outlast the engines. I personally haven't ever heard of a 258 jumping teeth without total timing gear destruction and that was on the newer ones with plastic gears.

[jamesdeanj]

Thanks for your help. I ordered a new cat and muffler and I should have them in and on by the weekend. I'll post when done and if I have more problems.