Failed CA Smog

redbullet

YJ Enthusiast
Joined
May 11, 2021
Messages
286
Location
San Jose, CA
Unfortunately my 1992 2.5L failed CA smog today, due to high NO (see pic). Anyone have experience with lowering these numbers. The shop said they think it may be due to an exhaust or manifold leak and we’re willing to confirm this for a $250 diagnostic fee where they would put peanut oil smoke in the system and look for leaks. I went home and connected my shop vac to the exhaust with duct tape to seal it and then let her blow. I sprayed soapy water and found leaks at the rear of the manifold. I am torn on whether to repair it or move on from the vehicle. I am sick of CA smog as my Jeep is running great otherwise.

8B1EC454-F7DF-455E-A974-D66185F5D083.jpeg


8B1EC454-F7DF-455E-A974-D66185F5D083.jpeg
 
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yup, same thing happened to me. My Tech said to look for exhaust leaks between the combustion cylinder and the o2 sensor, So it looks like your vaccum cleaner diagnosis is spot on. I removed my exhaust manifold and found 3 major cracks on the underneath side, I purchased a new manifold from Napa for under $100 bucks and installed it ( be sure to straight edge the mating surface before installing), I had to mill the mating surfaces to flatten them out, I used a floor mounted belt sander and it worked just fine. get creative and overcome. My 91 has passed Calif. Smog for the last 4 times with flying colors now. If this doesn't get you passed pm me for some quick and clean tricks of the trade to help in your quest . Tim from the North Bay
 
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Move onto another vehicle? Id Move on to another state, thats what we did. No matter what you buy it will be the same shite eventually. Far as exhaust leaks have you checked for missing manifold bolts in the rear most locations?
No missing bolts…I am going to do the manifold gasket, just a bit short on time and motivation right now. I love my YJ…California sucks
 
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No missing bolts…I am going to do the manifold gasket, just a bit short on time and motivation right now. I love my YJ…California sucks
doubt it's just the gasket but you'll see , I don't remember how many Expansion Plugs are under the gasket but make sure you you scratch and scrape and poke them with a sharp object to look for weak spots. Now is the time to replace them . I Think they were 3/4" plugs. I'll be in San Jose on April 1, would you like me to stop by for a few minuets to offer advice ?
 
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doubt it's just the gasket but you'll see , I don't remember how many Expansion Plugs are under the gasket but make sure you you scratch and scrape and poke them with a sharp object to look for weak spots. Now is the time to replace them . I Think they were 3/4" plugs. I'll be in San Jose on April 1, would you like me to stop by for a few minuets to offer advice ?
Thanks for the offer. I likely won’t be able to get after it for a few months, but I will let you know if any issues or questions come up
 
a few bolts on the manifold were very loose, so I re-torqued all of them…also swapped out the o2 sensor for the heck of it. System is no longer leaking. We’ll see if it passes the free re-test in a few days
 
a few bolts on the manifold were very loose, so I re-torqued all of them…also swapped out the o2 sensor for the heck of it. System is no longer leaking. We’ll see if it passes the free re-test in a few days
…in addition to this I ran a bottle of Cataclean through my gas tank and I…wait for it….passed SMOG!!!!!!
 
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