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1992, Jeep Wrangler YJ, Manual 4.0L - Work in Progress!
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Discussion Starter · #1 ·
So I finally picked up that 92 YJ and drove it home. 4.0L, Manual, drove it about 160 miles home, no issues outside of it being loud and running a little cold (it was about 30 degrees outside).

I go to start my traditional ritual of fluid changes and notice a little milkiness to the dipstick. Checked the cap, little bit, so quickly drained the oil but NO ISSUES with the full drain. Seemed fine. Press on and see what's next!

As I started to look into everything (radiator no mix, coolant tank little low but not ridiculous), I noticed there is black soot on the ground behind the tailpipe. Looks like black spatter on the ground. I don't see smoke or smell anything odd outside of the mistiness from the cold.

Any ideas? I plan to do a full run through before moving on with the real upgrades (body, suspension, etc)

I've never seen black spatter sitting on the ground though. Makes me nervous!

Thanks all.
 

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It sounds like unspent fuel. Check your spark plugs for soot, it may be running rich meaning that you have too much fuel going into the combustion chamber.
 

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1992, Jeep Wrangler YJ, Manual 4.0L - Work in Progress!
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65 Posts
Discussion Starter · #3 ·
I plan to replace plugs/wires/etc (although I think some of that was done). Any particular models the WF community sticks with or just stock?

Searching has netted me a ton of info to check, hoses, coolant temp sensor for the low temps, maybe fuel pressure regulator, seals for the injectors etc.

I don't mind replacing parts as needed, I just don't want to throw unneeded parts so I usually try to step through the issue and troubleshoot properly. Good news, it doesn't seem too bad.

One bad thing, I cracked the plastic front frame cover while standing on the front bumper leaning in. I'm short, and the jeep is lifted a bit (still identifying). Nothing some sheet metal, and rivets can't fix!

Damn I'm so excited to get back into a project!
 

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I have E3 spark plugs but most people prefer to stick with the OEM Champion plugs. The E3 plugs haven't made a noticeable difference. I replaced my spark plug wires with NAPA brand wires. $4 from Rock Auto. Rotor and distributor cap should be inspected or replaced at the same time, or at least sanded down to bare metal.

You should still check the plugs for soot. That'll indicate it's running rich or not.

This thread has some info.
 

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Check your codes, could point you to a sensor that is bad.
 

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1992, Jeep Wrangler YJ, Manual 4.0L - Work in Progress!
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65 Posts
Discussion Starter · #6 ·
Checked the codes...

And....

12
33
55

All expected from a 92 YJ. So that's a good sign I guess. I'm going to replace plugs/wires, etc. Then move on to all the fluids for piece of mind. I'll keep tracking down issues as they come, but one of the big ones is finding a welder to deal with the frame issue. Yep, it was cheap, and yep, it's a project.

But it's mine, and I can't wait to get it back to rockin!
 

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I would just do all the fluids and tune up you have planned. The milkiness on the dip stick is water, probably condensation. The black splatters are probably carbon soot that was loosened by your drive. I would bet this jeep wasn't driven much recently, and not enough to get hot enough to keep things clean. I wouldn't worry at this point, just keep wrenching away and enjoy the toy.
 

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1992, Jeep Wrangler YJ, Manual 4.0L - Work in Progress!
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Discussion Starter · #8 ·
So as I work through the issues, looks like no more carbon shooting out of the exhaust, coolant seems to be ok, tranny fluid changed and shifting seems nice outside of the first gear issue (from a stop).

One thing outside of the lifter noise (seems like it), I've noticed the temperature doesn't seem to get back the 155 mark, my reference being the tick between 1st and middle marks.

Maybe that's causing my rich condition. I have another thermostat, but it seems to me logically it could be the coolant sending unit? That's the one that reports to the gauge right? I don't want to just throw parts, but it seems to stick around that temp pretty solid and not get much more.
 

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50/50 it could be the thermostat stuck open/too low a temp rating(160*) or the gauge sender at the back of the head being bad. The sensor on the thermostat housing reports to the computer for mixture computation.

I strongly recommend using MOPAR thermostat and sender unit.

The wisest strategy with a new-to-you jeep would be to completely refurbish the cooling system whilst you have it drained for the thermostat.
 

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1992, Jeep Wrangler YJ, Manual 4.0L - Work in Progress!
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Discussion Starter · #10 ·
Yup, I'm thinking 160...

As I drove it around trying to heat it up, it stayed just over the mark, assuming about 160 based on the dash gauge.

So of course, in the box of parts I was given, a new t-stat and gasket was in there. Yeah, it's a 180. Figures, so I'll just take a drive to get a 195 I guess and go from there. Coolant was actually changed probably less than 5K ago by the PO, but for some reason he didn't swap out the T-Stat at that point.

Anyway, after cleaning out the CCV setup, cleaning the CAI setup (until I replace with stock), tranny change, and oil change, things are on the right path.

Once I get the stat in, I'll swap plugs at that time, and probably drain/fill my diffs and transfer case. That way I know at least the major fluids are done.
 

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1992, Jeep Wrangler YJ, Manual 4.0L - Work in Progress!
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Discussion Starter · #11 ·
Confirmed... No Water..

So I decided I needed to know!

I replaced the Valve Cover Gasket, cleaned everything (GROSS BTW), and cleaned the CCV setup, Air Intake, etc..

When I had the cover off I saw zero evidence of water/oil mix, so the condensation must have been the culprit. I'm glad I removed the valve cover though to prove this and clean this thing up. I also pulled the IAC, and Throttle Body and gave them a thorough cleaning. Now I'm out of cleaner and gloves!

Next is the thermostat, and new wires/plugs/cap. Once I get the mechanics to a point I feel solid, body work and frame repair will be next up. Still haven't been able to find a welder in the area that will fix the rear right for a decent price!
 

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That black coming from the tail was probably condensation and some soot as the exhaust heated up, they do that down here in the South all the time, when one see's it they freek out, but most of the time you get in your car, start and drive off, you can't see the water running out the pipe while driving, but you can see it happening to a car that pulls out there drive in front of you from there drive on a cold morning.
 
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