1988 yj 4.2 need advice - JeepForum.com
 
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post #1 of 3 Old 11-27-2017, 05:52 PM Thread Starter
clint67
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1988 yj 4.2 need advice

recently had head redone ran good at first then started smoking and idleing poorly. i have two what looks like pcv valves on the valve cover one up front and one in the rear. getting oil in the intake. any advice? did compression test cold will this give accurate reading?


Last edited by clint67; 11-27-2017 at 05:54 PM. Reason: needed to add something
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post #2 of 3 Old 11-28-2017, 11:55 AM
Que89YJ
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You need to check the PCV and the CCV on the valve cover and both hoses to each. You can put in a catch can as a quick temporary fix.

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post #3 of 3 Old 11-28-2017, 12:16 PM
mark1305
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Also, to clarify, the hose from the PCV should go to vacuum and the other hose should either draw air from a small filter in the outer rim of the stock air cleaner if its still there. If not, many folks attach a small pod filter in that grommet on the valve cover.

The way the system is supposed to work is air is drawn from the PCV by the engine and blowby fumes burned in the engine. Fresh air is supposed to be drawn into that second hose and into the engine to avoid creating enough vacuum to suck oil from then top of the cylinder head into the intake tract.

Not sure if you have to pass emissions/visual inspection where you are.

If it was just smoking and idling rough I would hazard a guess that one or more valve stem seals may have slipped off the valve guide and allowing oil to get drawn into that cylinder. But.... getting excess oil in the intake or air cleaner means something else is going on and could involve the PCV system.

Try searching on here for PCV troubleshooting on carbureted 4.2L engines. May have to play with search terms but pretty sure you'll find some info.
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