Engine running rich..can that cause oil in air filter?


Old 11-21-04, 05:04 PM
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Question Engine running rich..can that cause oil in air filter?

I have a 1991 Jeep wrangler 5sp 6cyl. that has oil blowby going to the air filter. I was told this may be caused by engine running too rich causing gas to get in the oil & shoot out the pcv valve. Several questions come to mind. 1. How do I know if I am running too rich? 2. How do I correct that? It was also suggested I switch to 10w40 but is that a good idea this time of year in VA? I loose about a half a quart every 500 miles or so. Some of that winds up in the air filter. Thanks for your advise.
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Old 11-21-04, 05:33 PM
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It sound more like engine wear to determin the cause you need to do either a leak down test or a compression test.
The amount of fuel needed to blow oil into the air filter would result in poor performance and most likly a missfire.
Old 11-21-04, 07:31 PM
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Thanks for the quick reply, but...1. what does running rich mean? 2. how do you fix that if you have it? 3. can I switch to 10w40 oil this time of year in VA? 4. how does gas get into the oil? Thanks
Old 11-21-04, 07:43 PM
Join Date: Nov 2001
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black smoke

Are you blowing black smoke out the exaust if so that is a good indication of a rich running engine.
Old 11-21-04, 08:42 PM
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1.Running rich means there is too much gas pumped into the combustion chambers, it's not all burned in the combustion proccess, and it usually exits the tailpipe as black smoke and leaves your tailpipe black and sooty

2.Your computer should be controlling all aspects of fuel delivery, it would have to be a serious malfuction or failure of something to the computer not to compensate for it (not like the old mal-adjusted carb days, no screw to turn)
Start by checking for memory codes stored in the computer
Those codes or lack of them will determine your next step(s)

3. Yes, if it doesn't get below 0*F before the next oil change

4.If you were dumping fuel into the combustion chamber, some could slip past the pistons and into the crankcase and contaminate your oil
If you were running rich enough to blow black smoke I'd say you're oil is contaminated
Old 11-22-04, 12:38 PM
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I know a lot more now about running rich...

Thank you all for the information...It helps clear up a few things...I don't see any smoke, black or otherwise. I do however, have black sooty stuff around the rim of the exhaust tail pipe. Perhaps the oil-return holes are partly blocked for oil to drain back down into oil pan. when I replaced the valve cover gasket, a bunch of black 'chunky' stuff was around the rocker area. I cleaned all that I saw, but may have missed some in the drain area(if there is such a place.) Anyway, someone suggested I check the oil return holes to make sure they are not clogged. Thanks again for all the info...Helps me understand what may be happening.

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