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Unread 12-22-2009, 10:28 PM   #1
Group_er
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Vacuum Lines, PCV Valves, And BlowBy....Im having Issues

I was hoping someone could help me out with a hopefully easy question.
I'm running a CJ 4.2 I6 With no emissions, And an after market air cleaner.

Heres a pic of the motor compartment.



You can see my breather up front, then a plug, then the rear vacuum line runs to my brake booster, and from there, it goes to a vacuum port on the carb.

I am experiencing oil coming out from around the seat, and the breather assembly its self. If I wipe it away, It will start running about 1/2 way down the valve cover in a couple decent drives.

Im 95% sure this is because the motor is getting tired, and has excessive blow by. Im still holding onto the faint slight possibility the routing of my vacuum lines or something like that may be causing this.

But getting on here......

I am also experiencing slight weeping and or seepage from around the fitting for the vac lines, that enters the brake booster. I am assuming this is oil buildup. I can really only tell its leaking from a slow collection of dirt and dust sticking to the booster.
See pic:




I mentioned this leak to one of my local mechanics, who informed me that the oil (99% sure it is oil) will damage the diaphragm inside the booster eventually. The booster is bran new, and I DONT want to be replacing it for many many years to come!

I was really hoping someone can let me know if my vacuum lines are correctly routed? or possibly causing more blow by than necessary?
Would I be able to T into my vacuum fitting on my carb (that Im using now) And run separate lines to the booster, and the valve cover? Would This eliminate my oil blow by entering inside my booster?
It sounds like it would to me!?

Thanks for any help or opinions everyone!!


Last edited by Group_er; 12-22-2009 at 10:40 PM..
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Unread 12-23-2009, 12:17 AM   #2
Coiz
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Your last statement is correct. The brake booster vacuum line should be a direct shot to manifold vacuum. Nowhere should it T into a PCV line.

Very clean looking engine compartment BTW.

Edit: I just noticed another picture of your engine compartment in another thread that shows two vacuum lines on the fitting at the brake booster. Mine only has one coming out of the bottom of the fitting and the face of the fitting is blank. Here is a picture of yours with two lines connected. Hopefully someone can shed some light on the differences.
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Last edited by Coiz; 12-23-2009 at 12:43 AM..
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Unread 12-23-2009, 03:37 AM   #3
keith460
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I wouldn't use that type of fitting to "T" with the brake booster as a vacuum source but I have seen that setup before. Not sure if that is a required check valve though.

Brake Booster vacuum should directly come from the Intake manifold and I see in your photo that you have a brass pipe plug below the carb that you should be using. That is where the factory vacuum source comes from for the Booster. Use a single Check Valve fitting for the Brake Booster fitting.

PCV is another device that needs full manifold vacuum at all times so look for another source below the carb throttle plates for vacuum hook up. In the photo below, the label "To: Factory Air Cleaner TAC System" is the vacuum source for the Brake Booster via the tube fitting out of the brass fitting.



Another photo shot of the vacuum source for the Brake Booster above the EGR valve.
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Unread 12-23-2009, 08:48 AM   #4
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Quote:
Originally Posted by keith460 View Post
I wouldn't use that type of fitting to "T" with the brake booster as a vacuum source but I have seen that setup before. Not sure if that is a required check valve though.

Brake Booster vacuum should directly come from the Intake manifold and I see in your photo that you have a brass pipe plug below the carb that you should be using. That is where the factory vacuum source comes from for the Booster. Use a single Check Valve fitting for the Brake Booster fitting.

PCV is another device that needs full manifold vacuum at all times so look for another source below the carb throttle plates for vacuum hook up. In the photo below, the label "To: Factory Air Cleaner TAC System" is the vacuum source for the Brake Booster via the tube fitting out of the brass fitting.



Another photo shot of the vacuum source for the Brake Booster above the EGR valve.
Great! Thanks Guys!!! I will hook my brake booster to the hole under the carb, That is plugged at the moment. And I will run a separate line to the pcv valve, coming of the vacuum hole im using for both at the moment!
Great help guys!

I do have 2 more questions thou:

What is this "single check valve fitting" you speak of? hehe

And another thing I noticed, and just remembered was: When my motor is idling I pulled the PCV line (I believe a check valve) out of the valve cover and my motor didn't idle up like I thought it would have....Is this right?

Thanks everyone!
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Unread 12-23-2009, 01:39 PM   #5
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The photo above shows a single type check valve, which is a one-way valve that only allows air to be sucked out of the vacuum booster. If the engine is turned off, or if a leak forms in a vacuum hose, the check valve makes sure that air does not enter the vacuum booster. This is important because the vacuum booster has to be able to provide enough boost for a driver to make several stops in the event that the engine stops running -- you certainly don't want to lose brake function if you run out of gas on the highway.
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Unread 12-23-2009, 11:10 PM   #6
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Right

Thank you. I am switching things around tonight and tomorow, And will report back in a few days with my leakage...
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Unread 12-24-2009, 12:35 AM   #7
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'Just came in from the shop.

Can anybody tell me if the One Large vacuum port at the back of my motorcraft 2100 is sufficient for the PVC valve?
Going to hook it up tomorrow morning if it is!
Thanks!
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Unread 07-08-2013, 08:38 AM   #8
smitty010203
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This is where the connection is for my booster vacuum. any idea what the smaller hose is supposed to be connected to?
brake-boost-vacuum.png

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Unread 07-08-2013, 09:21 AM   #9
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Agree with Keith on using the brass fitting on the intake just below the carb as the source for your booster vacuum. There's a brass cap on the end of the fitting that once removed can be replaced with a 5 inch length of 3/8 steel brake hose with a standard 5/8 fitting, bent halfway at 45 degrees like in Keith's photo. On the issue of blow-by, it looks like your breather cap is installed in the oil fill hole in the valve cover. This is where the oil cap usually goes and it has no baffle underneath to prevent oil from blowing up into the breather. Move the breather to the breather port in the rear of the valve cover and this should minimize the oil seepage in the breather. However, if your blow by is bad enough, you'll probably still see oil/water condensation on the breather just not as severe as it was at the oils fill port.
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Unread 07-08-2013, 01:31 PM   #10
keith460
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Quote:
Originally Posted by smitty010203
This is where the connection is for my booster vacuum. any idea what the smaller hose is supposed to be connected to?
That is the original vacuum port for the OEM air cleaner TAC system. It's just another source for manifold vacuum if needed.

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Unread 07-08-2013, 01:52 PM   #11
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Thanks keith, actually posted that on this thread by accident but whatever works to get an answer
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