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My Renix blowby fix.

BB1980

NAXJA Forum User
Location
Seneca, SC
filters.jpg

So, we all know the story.... Filter on right was driven for a couple of months, the one to the left of it was driven for 3-4 weeks on and off.

stockintakehose.jpg
stockrearvc.jpg

I had the stock tube on the rear valve cover to intake connection, and a large heater hose running from the front valvecover connection to the airbox since the original hard plastic line had broken on the front.

While fooling around at work (Advance Auto Parts) I took off the brass nipple that screws into the intake and brought it in.

I found the thread of the intake manifold and then found that we sold an adapter from that thread (1/4" NPT) to 5/16th brake/fuel line. It was $1.50. Next I got a 40" piece of 5/16ths metal line for $5. I also found that we can order the plastic emissions harness that is on the Renix engines for around $21 per half, so $42 for both sides. I didn't have to replace these necessarily, but I had had to splice rubber hose between broken plastic ones and had a large heater hose running from the valve cover over to the airbox.

Adapter:
adapter.jpg

Brake/Fuel line. BL-540 at Advance is 5/16 line, 40" long.
brakeline.jpg

It also helps if you already have a line bender or can do it without crimping the line accidently:
bender.jpg


Here is a comparison of the rear connection vs the brakeline and the front brass nipple vs the new adapter:

rearcomparebig-1.jpg


SO, the process is simple. Remove the old rear tube. Remove the brass nipple from the intake manifold. Thread in the new adapter to the intake. Start bending your metal line to run from the intake to the rear valve cover connection. You will wind up cutting off around 6" of line at the rear and removing the flare nut from that end. I then started the flare nut into the adapter on the intake manifold. Before completely tightening the flare nut, push the rear of the metal line into the valve cover grommet. It is a tight fit, and you will feel it go in a short distance and then stop. If you keep pushing harder, you will feel it go through another part of the grommet and then feel it start into the valve cover. Pull it back out just a little so that it is still engaged into the bottom piece of the grommet. Then you can full tighten the flare nut on the front end.

adapterscrewed.jpg

done.jpg


This is the finished product with my old heater hose line from the airbox to the front of the valve cover. This should've worked fine for most people, but I knew a lot of my vacuum lines were all old and broken and spliced and some were possibly hooked up wrong:

newlineoldfrontvc.jpg


Here are the two halves of the harness I purchased through work for $42 total:
newharness.jpg


And here is the final installed harness. I did have some vacuum lines ran incorrectly. When I bought the jeep, all the lines were in the rear hatch along with the valve cover, injectors, and fuel rail. So, I had to wing it hooking them up trying to do it off of a vacuum line diagram I found online.

newnew.jpg


The much larger rear connection should keep from clogging with crap and allow the proper direction of flow from the airbox into the valvecover and then into the intake manifold to be burned. In the terrible event that it does get clogged, it can be removed, cleaned and reinstalled without worry of breaking a small plastic pipe like before. I have installed another new air filter and will monitor it every week and post up results. I drove the jeep shortly afterward and it seems to run and accelerate just fine with the larger line potentially making the A/F mixture run lean. In the end, if you only need to replace the rear line to prevent blowby, you can do it for less than $8.00 at your local parts store.
 
The problem you solved is only half of it. First the passages for the oil returns in the head are clogged with the same crap that has clogged the line. That valve cover is also of poor design in that under those connections are tubes that run down and stop about 1/4" away from the top of the head which in turn sucks up the pooling oil. I hope that what you did fixes your problem but I had to replace the valve cover and I just put a breather on the front orifice. It was a Mr. Gasket 2057.
 
I got the one for the wrangler. quadratec sells them and Crown automotive makes them
 
I switched to the late model V/C and harness. $20 in the local yard. It also cleaned up the underhood quite nicely. Just make sure to get the manifold fittings while you are at it.
 
well after seeing that you can get them at advance auto parts I looked them up and I can get them at my store too (A&A Auto) and my price is only 10 bucks each half of that vacuum harness - ordered them up they will be here monday
part numbers are HELP number
46003(looking at engine to the left)
46004(looking at engine to the right)
and the one that you used the brake line for:
46005
 
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I thnk some one else had this idea about 1 yr ago.
IMG_0046.jpg
 
It looks like they replaced only the front hose straight to the airbox, but not the rear one. The rear one is the culprit behind the blowby. The direction of flow should be from airbox into front of valve cover, through and out the rear of valve cover, then into the intake manifold via the tiny hard plastic line. By swapping the rear line out with later model lines that are larger, or making a steel one out of fuel/brake line that is larger, you fix the blockages that make the engine vaccuum back-suck from the front valve cover connection into the airbox. I need to post up a new picture of my air filter. It is still white and clean with NO oil in it after making the metal line.
 
You guys need to be a little careful with that back line mod, the small tubing. It should have a 2.2 to 2.5 mm ID restrictor in the line, otherwise you get the equivalent of an intake manifold vacuum leak that runs the idle rpms too high.
 
I haven't had any noticeable problems with mine yet. I am working on a PCV jar to add in line and then maybe putting a restriction after it so that the crap gets filtered out before it can clog the restriction. But this is a nice fix until then.
 
I had a hard drive crash and lost the bookmark I had that started with some of the info fixes for the older valve cover problems. It had a lot of responses and then one poster got into a replacement of the vacuum line with steel lines. He included pictures of his total vac line system replacement with steel. It was several years ago and I am now wanting to complete that fix. Can anyone help me out.
 
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