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Unread 11-22-2015, 04:24 PM   #1
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Blow back

my 88 2.5 wrangler is leaking oil out of the oil fill cap. What is clogged?

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Unread 11-22-2015, 04:32 PM   #2
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1993 YJ Wrangler 
Join Date: Mar 2009
Location: , Ct
Posts: 1,243
Check your pcv valves... If you take them off and shake them you should be able to hear something moving in them.... Check all the hoses to them and also take off your valve cover and clean the baffles... All culprits for blow-back or blow-by...
93 YJ, 6 cyl,3.5" BDS,1" Prothane BL,1/2" booms, 33" Mickey Thompson MTZ on MT Beadlocks.

Do your part for Leukemia research - help find a cure.
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Unread 11-22-2015, 06:10 PM   #3
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1995 YJ Wrangler 
Join Date: Jun 2013
Location: New West, BC
Posts: 1,247
Is there oil in your airbox? is there oil coming out of the orifice on the PCV/CCV ports? if no to these questions - it may just be as simple as you need a new oil cap.
Stop whining about the 'ride' - If your YJ ain't wrangling your soul free, then might I suggest you buy a stationwagon... at least you can fit all your bull**** in the back.
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Unread 11-22-2015, 06:31 PM   #4
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1991 YJ Wrangler 
Join Date: Aug 2005
Location: phoenix, az
Posts: 2,614
Don't bother messing around checking the PCV valve, just put in a new one. Rattle or not, they need to flow a specific rate. Trace all the rest of the PCV lines and pull them to clean them out and make sure there are no leaks, cracks, hacks, or restrictions. Then inspect your oil cap. If the rubber gasket is cracked, hardened, or just doesn't seal snugly, replace the cap.

I've has more than one 2.5L that had the PCV vacuum port at the base of the throttle body completely blocked by hard crust deposits. Cleaned the port and voila, the leaking valve cover gaskets and oil cap stopped spewing till I could renew them.

91 YJ Sahara, 4.0L, AX-15/NP231, D30/D35
12 Cherokee 4x4,3.7L,
"Non Vi Sed, Arte"
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