89 yj smoking... engine swap or ? - JeepForum.com
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post #1 of 7 Old 09-11-2011, 03:24 PM Thread Starter
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1989 YJ Wrangler 
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Location: El Sobrante
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89 yj smoking... engine swap or ?

Hey all I'm a newbie to this forum and a Jeep newbie in general.
So anyhow I bought my first Jeep a few months ago now and unfortunately didn't have any knowledge of them. After buying a buddy in Colorado informed me, 89 is headache and tried to guide me to sell and get something else. Well I'm not able to do it, so I gotta work through it.
So lately she's been smoking intermitently, seems like sometimes she does upon start up a bit and others upon stopping (may be just unnoticeable in movement). Being Carburated she's always smelled rich, but now is more apparent. One of my buddies suggestions was an engine swap to Fuel Injected 4.0L right from the start, so I've been looking but upon doing so am seeing I'll need a whole lot more than just the engine... computer, wiring harness, fuel pump and lines etc. etc. etc.
I drive her and though I plan to do more offroad, she needs to be street legal.
Being in CA that means 'Smog checks' every 2 years.
I'd be totally happy keeping the stock 4.2L (tilll maybe a later date, or forever), but ABSOLUTELY have to solve the smoking issue. I recently got a notice that someone reported it, so now 'the Man' is watching me.
HELP!!! I found some links on here (OMG there are millions it seems) on things to look at, and have gone through some of the checks... PCV seems good (as it rattles as suggested), stepper motor, computer and O2 sensor working (not sure if that means they are working 'correctly', but the carble needles are apparently adjusting mix as they are in motion, so ????
Anyone have more, suggestions, opinions etc?

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post #2 of 7 Old 09-11-2011, 04:12 PM
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Hello John, a rhetorical question and then some links to assist you. You've a bit of research/wrenching to do but it'll all settle out

What color smoke?
White (other than at startup) = head gasket/cracked block;
Blue = burning oil - rings, valve guides, valve seals;
Black = rich fuel mixture.

What's under your hood:

If the smoke is black see items 2,3,4 in the center column; you may wish to get a rebuild kit (Carter 8384) and carb cleaner, about $20 total and rebuild. There are plenty of threads on this site about it - easy, take your time, pay attention during disassembly and reassemble accordingly; instructions in the kit are very good. Standard fuel mixture settings for both screws is 2.5 turns out from a gently seated bottom.

How to read spark plugs for engine problem diagnosis:

Factory Serivce Manual for the Carter BBD:

Using a vaccum gauge (connected to manifold vac) for engine diagnosis:

These should provide what you need, to know if it's a tuning issue or mechanical problems.

Take care.
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post #3 of 7 Old 09-11-2011, 11:08 PM Thread Starter
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thank you for the links and help. Speaking of which, your first link goes to a 'earthlink' page, can you confirm that link?
Though you said it was rhetorical, the answer is... blue.
Any immediate 'bandades' I can do?
Also any ways to diagnose, if its rings or valves or valve seals?

On now to read up on those links.

Thanks Again.
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post #4 of 7 Old 09-11-2011, 11:10 PM Thread Starter
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o and it looks like the link for the carb is a repeat of what you put for the first (reading spark plugs). link.
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post #5 of 7 Old 09-12-2011, 07:54 AM
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Best way to tell the health of the engine is to perform a compression test on the cylinders. Your readings should be about 140lbs but just as important they should all be within 10% of each other.

Your oil pressure should not drop below 20psi at idle with a warm engine. This would normally indicate worn main bearings.

The 4.2 is a great motor for the Jeep. No need to replace it. You will hear others say diff but its low end torque is what off roading calls for.

87 YJ The Original!

Originally Posted by Anticanman View Post
It goes in that barrel you wheel out to the street once a week.

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post #6 of 7 Old 09-12-2011, 12:25 PM Thread Starter
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have an issue with oil pressure gauge too... as soon as you turn key, needles pinned past 90 psi. I've looked at everything I found online and still no resolution... someone says its a bad ground, but wouldn't that affect all the other gauges too? They all work so? I actually am debating eliminating the plastic/paper electric board and hardwiring the gauges.

Will look into the compression today maybe.
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post #7 of 7 Old 09-12-2011, 07:33 PM
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Hello John, apologies for my previous sloppy post. Here's a correct "under the hood" link:


and here's the FSM for the BBD:


It appears you've got mechanical problems due to the blue smoke; rings, valves, valve seals/guides etc. so the above correct links are secondary to your issues. Sorry, but no temporary bandaids for your symptoms.

Reading the plugs and vac gauge links I provided before will give you general diagnostics before you do a comp test as previously suggested, but the comp test will be definitive. Manvac at sea level on a healthy engine at idle should be about 22 inches and a steady vac gauge. Subtract 1 inch of vac for every 1000 feet of elevation above sea level.

Best of luck!!
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