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Old 01-26-2012, 07:47 AM   #1

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No air filter

I was looking at a YJ to buy and it didn't have an air filter in the box, and no idea how long it had been like that (dad selling for son who moved away). Anyway, how much damage can that do? I'm assuming he had it off road also but like I said not sure when or why he took it out. Is there any reason you would want to do this?

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Old 01-26-2012, 08:48 AM   #2
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Old 01-26-2012, 11:43 PM   #3
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Tips from the Beas

First question would be is it an Inline 6?(4.0L) If so, not too much dirt and grime could have gotten in the piston chamber due to the severity of the bends in the intake manifold. All that a filter does is prevent dirt and big grime from getting into a cylinder. Water will be burned out and even if a little wet dirty poop got into it, the heat from the camber will eventually dry this out and it will blow out as long as there is no serious existing piston wall damage. A simple compression test would let you know if there was any blow by. Another thing to look for is dirt in the hose from the filter box to the throttle body. You should be alright. Just let it run a bit and while in neautral, give it some gas and bring the RPM's up a bit and look for any serious hesitation; I mean very serious, the motor will almost hop if there is extreme cylinder damage. Do this with a foot on the brake in the gears also! You can also do a rebuild to the 4.0L for about $300 if you do the work. Just did mine and the trans too! Good luck. Hope this helps!
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Old 01-27-2012, 04:01 PM   #4
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It does ... a bit more peace of mind, thanks!
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Old 01-27-2012, 04:15 PM   #5
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How did the oil look? The air cleaner takes a lot of dust out of the air which is abrasive. This dusty air goes right into the combustion chambers, wears rings,it can score the cylinders, bearings etc. oil will trap some but its not good to run without an air cleaner.......
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Old 01-27-2012, 04:56 PM   #6
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x2 on the compression check. also, take off the tube btwn the air box and throttle body, see how dirty / dusty it is will give you an idea of the junk getting into the intake and possibly cylinders
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Old 01-27-2012, 09:14 PM   #7
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Running without the air filter isn't going to do SERIOUS damage if it's mainly road use. These engines are pretty tough, but it's not like it's going to dramatically shorten the life of the engine if dust gets inside.

Definitely check it out like others have suggested. If it checks out all good then I'd imagine it will be fine.

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Old 01-28-2012, 11:37 PM   #8
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Tips from the beas

I have to agree. You won't get a whole lot of wear in the cylinders from the street without a fliter. You would have to suck in rocks to do any damage in the dirt. I think it will be fine. The old man probably pulled the filter, because it was dirty/oil from the smoke tube that runs off the valve cover back to the air box so nobody would see it. Iinline 6's are pretty tough motors and you would need to have ran without a filter for a long time do do any serious damage. Good Luck. Post some pics if you buy it!

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