Some problems and questions

Hello, everyone. I bought a 1980 CJ5 in March, and have enjoyed having it. I knew hardly anything about how cars worked, but I have already learned a ton and have done all my own repairs on it so far, which have included replacing the brake and clutch master cyclinders and just general maintenance like changing oil. But those are relatively easy and now I'm stumped!

Starting yesterday morning the Jeep is majorly hesitating/sluggish/laggy upon acceleration in the higher range of 2nd gear a little, and mostly in the lower range of third gear. When I shift from 2nd to 3rd, and give it gas, it sounds "bogged down" and doesn't accelerate until I push the gas a lot more than usual and then it sounds kind of like it "comes clean" and the engine sounds more normal and there's more of a burst of power/speed as I get past this "wall." This has continued since yesterday morning, and I drove it probably 3 or 4 times around town yesterday, but it would diminish a bit as I drove, but after I parked it and started up again, the sluggishness returned. Same this morning.

I have done a couple of things recently. First, my Jeep leaks a ton of oil, something I'm trying to fix. I think it's a gasket in the transfer case or something, and possibly one around the "breadloaves" (I'm still learning all the terminology, I think they're the rocker covers? Where I put in the oil). So, trying different advice I put in some Marvel Mystery Oil about a week ago. I thought it made the engine sound a bit better and run a little better, but maybe it was placebo, but I also think it thinned out the oil a bit and caused it to leak more (it's also 105 degrees here right now). So, I changed the oil the day before yesterday, and instead of MMO, at the recommendation of my dad, I used STP's oil treatment, the thick "oil honey" hoping it would also help the engine run well and maybe not leak as much.

The last 2 fillups I added an STP fuel treatment the first time and the last time I added a few ounces of leftover MMO.

I don't really have any idea how well the jeep was maintained by previous owners, and I know when I changed the oil when I first got it, it was black as night. I'm thinking maybe some routine maintenance was not kept us so well, so I was hoping using some fuel additives and oil additives might do some cleaning up, but could they have dislodged something that would cause the sluggishness? The fact that it is always occuring when I shift into 3rd makes me wonder if it's something else.

Also, I'm learning as I go, so although I've changed the oil and things regularly, I'm learning about more routine maintenance that I need to do that has not yet been done. For example, I took a look at my air filter and it needs to be changed, which I'm getting one today. Could the engine possibly just be starved for air? Or would it be starved for air everywhere and not just when I switch into 3rd? I was thinking I should probably change the spark plugs and fuel filter as well?

Thanks for all your help.

*Edit: Forgot a major detail I think. It has a Chevy 350 engine, not stock. It is carbureated, but I don't know much about carbs or anything so I don't know if they're any different. Thanks again!

 

Well Golly,

Can you tell us some more about your Jeep? Engine, trans, etc. It would be help us to help you.

 

Yeah, sorry I forgot those "minor" details lol. I'm new at all of this.

It has a Chevy 350 engine, I'm not sure what year. The transmission is what I've been trying to figure out. It says T18-1B on the side. From what I've been seeing online, some Jeeps came with T18a's but I'm having trouble finding out T18-1B's. I found somewhere it said they were in some Fords, and one place even said the T18-1B was still a T18a, but a later model, but I don't know much about this stuff yet! It's pretty obvious somebody at some point did a lot of work to it, because of the lift, engine switch, I'm thinking the transmission isn't stock, and I dunno about the transfer case or anything yet.

 

I suggest that you do all the maintenance you can think of - change all the fluids, grease everywhere there's a grease fitting, adjust what's adjustable, and do a complete tuneup. Then you can start your assessment. Hopefully the previous owner told you a little bit about the engine you have now, so you can buy the right tuneup parts.

Even with the Chevy engine, the factory service manual (FSM, TSM) will be very helpful. They are expensive but they are the best. This is one source for the manual - there are others http://thejeep.com/shop/TECH+MANUAL....html?osCsid=846c1ecb574b58804bdcf3f540b0d4a0

 

OK thanks. I'll look into that FSM. I have a Hayne's manual that has been extremely helpful, and I've been reading an Auto Mechanics Fundamentals book I checked out from my college's library. It looks like it's a middle or high school textbook, so it breaks things down really clearly and has been great.

I was thinking I needed to change the transmission fluid, but wasn't sure what kind to get because I didn't know about my transmission type. That's when I discovered the T18-1B stamped on it, and the auto parts man said he didn't know, but would guess a 75W-90, which is what the Hayne's manual suggests for "all other" transmissions but I wasn't sure if that would apply to not-stock transmissions, if mine is.

I'm also unsure of the differentials if they're stock or not and am trying to see if I can find any sort of marking. I was thinking with all the other modifications that were done, it's possible they aren't stock either.

Thanks for your help.

 

80W-90 GL4 would be a good trans fluid for you...I think NAPA carries it.

Here's a link to an axle identification chart (there are others out there as well)

http://coloradok5.com/axleguide.shtml

And some other CJ5 info with links

http://www.jeeptech.com/models/cj-5.htm