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is Renix 4.0L valve cover fresh-air CCV hole diameter same as for '94 4.0L & later ?

MikeESoc2

NAXJA Forum User
is Renix 4.0L valve cover fresh-air CCV hole diameter same as for '94 4.0L & later ?

I have an '87 4.0L XJ ... am looking to replace the valve cover's front CCV fresh-air-in connection with a more simple grommet-elbow and flex-hose (fuel line) directly to the air filter intake ... instead of buying the NAPA replacement large plastic tube OE set-up (#7151367 and maybe #7151366 also).

I'm looking to do this so that in the future it will be less likely that I'll break the large plastic CCV fresh-air tube when cleaning the built-up sludge... since I have intentions of clearing that fresh-air-in line more often in the future.

I'm not looking to replace the '87XJ's valve cover itself... just the cover's front hole tube set-up.

I've read thru a large# of blow-by and valve cover postings today (I'm getting worn out from reading all that stuff).

But I have not found a posting regarding whether the later-90's XJ valve-cover CCV (PCV) grommet Dorman/Help #42344 and matching #47079 elbow is a good fit in the front CCV hole for a Renix aluminum valve cover (note: Dorman lists the OE#s for those 2 parts as 2946079 and 53030497).

I could order both the NAPA #7151367 direct-replacement for the '87XJ and also order the 2 Dorman part#s for the later-90's valve cover CCV hole ... but if the later-90's parts fit the '87 valve cover CCV hole then I don't know if NAPA will take back the Renix part.
 
Re: is Renix 4.0L valve cover fresh-air CCV hole diameter same as for '94 4.0L & late

The early hole is round, 91 and later round with key type slots kinda like a gas filler neck.
 
Re: is Renix 4.0L valve cover fresh-air CCV hole diameter same as for '94 4.0L & late

Since posting the question I've been looking around more, and my latest thought is this:
combining info from both
http://www.jeepxj.com/JeepXJ/oil blowby fix.htm
and
http://www.bonnevilleforum.com/showthread.php?t=206818
I may order:
Dorman/Help grommet # 42059 (different # than any that I originally posted)
and
order a breather vent cap (whatever brand) for a push-in diameter 5/8”.

Here is a 5/8” O.D. vent K&N breather filter (item price $18.99 a bit pricey):
http://www.jegs.com/i/K&N/599/62-1020/10002/-1#
which was found via:
http://www.knfilters.com/vent.htm

And as a 1st-step to any of the above, I'm thinking about enlarging the I.D. of the plastic restrictor in the vacuum-in line (to the valve cover rear hole).

That is:
initially not replacing with fuel line for the vacuum-in but just drilling-out the inside plastic restriction (have not yet decided how much to drill-out to... using caution)...
I made some volume %-increase calculations and I think that I am going to first try to drill out to 1/8" (~3.3mm) diameter and then after driving around a few days and testing I may try to then drill out to 3/16" (~ 4.8 mm) if possible.... to go bigger after that I believe it would be time to replace the plastic line with 1/4" fuel hose.
 
Re: is Renix 4.0L valve cover fresh-air CCV hole diameter same as for '94 4.0L & late

You can purchase one half of the vacuum harness, it sounds like you need it.

You can purchase both halves of the vacuum harness, and unless your 87 has had them replaced recently you are going to need it eventually.

You could source a later model valve cover at the salvage yard and then use the later style CCV components.

You could pull into the Napa parking lot, pull your junk and walk inside where the nice man behind the counter will fix you up with exactly what you need--or call you crazy, I've had it both ways a lot of times.
 
Re: is Renix 4.0L valve cover fresh-air CCV hole diameter same as for '94 4.0L & late

I'm pretty sure you can purchase all the vacuum harnesses at Napa for under $35. No sense reinventing the wheel.
 
Re: is Renix 4.0L valve cover fresh-air CCV hole diameter same as for '94 4.0L & late

Here's where I'm coming from on this:
last weekend I pulled the CCV plastic tube vacuum-in line and with the engine running felt that there was a serious amount of vacuum at the intake manifold connect rubber elbow for that line... but blowing thru the removed plastic line it appeared to be somewhat restricted... so I sprayed some brake-parts cleaner and carbureattor cleaner thru the plastic line until the cleaner exited clear... then blew thru the line again and it felt a little less restricted (but not by much).

As part of plugging back in the plastic line I added plastic wire ties to all connection points (could have used small hose clamps instead) ... around both ends of the 90-degree rubber elbow on the manifold connect and also around the top of rear grommet... this nicely snugged-up those connection points so that those points didn't have any wiggle room.

The "wow" surprise is that it felt like there was a bit more acceleration (especially from a stop) and also that the idle was slightly better... which I attribute to snugging up all the line-connection points with the plastic wire tires... which makes me wonder what the result will be if I where to slightly reduce the plastic restriction (start out by drilling it out 1 size larger).

And last weekend I also removed a connection point in the CCV fresh-air-intake line and saw all the gunk that is in that line.

Since sleeping on it overnight, I have decided that the next time that I order some parts from RockAuto that I'll include the Help grommet #42059 (it's an '86 CJ7 2.5L emissions grommet) and then go over to Lowes or Pep Boys (etc) and match-up a 90-degree elbow (probably 5/8") and then buy the rubber hose... followed by connecting it all up to the CCV fresh-air intake.

That is: my thought this morning is that the fresh-air vent breather filter (e.g: the K&N I had listed prior) is probably not the way to go because it eliminates a possible slight vacuum (? venturi ?) to occur thru the fresh-air CCV (should the CCV rear main vacuum-in become clogged and I don't know about it).

I guess that if I wasn't into slight modification for the experimental result, I wouldn't have hooked up the Crane Cams Hi-6S multi-spark ignition unit some years ago nor installed the Bosch Euro headlamps (from Canada)... etc ... etc.

This stuff is good... until I break something.... yeah, I keep forgetting... if it's not broke don't fix it.
 
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