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Discussion Starter #1
a week ago i posted that on my 406 motor i had erractic oil pressure that dropped when you brake and seemed that the oil was all being pumped to the top of the motor and becoming stuck in the valley. I also said that when you shut the motor down about 2min after it would chug like turning a milk jug upside down and i could hear all the oil draining in the pan... If you remember this post some people wrote to change to a lighter oil since i was running 5-50.

Well heres the thing, I changed oil to a 10-30 and ran the motor drove around for a bit and started to lose oil pressure again. I took the car home and sure as shit its doing the same friggin thing.. I can still hear it chug just not as load since its a lighter oil..

So after doing this a few times by running the motor and driving around, just till the pressure started to drop i would shut the motor down pull a breather, then a valve cover on a fluke i pulled the dipstick and WOOSH. Pulling the dip stick drained all the oil instantly! So i ran the motor again pulled the valve cover and tried to see what was going on, i wanted to try to see the oil in the valley while i had someone pull the dip stick. I couldnt see anything since the oil that dripped on the header blinded me. But i could hear it!.. So anyone know whats going on here? is it all crankcase pressure that is holding the oil up in the valley so it cant drain down the 2holes in the back of the block and the 2 holes in the front???? I have the 1/4" holes plugged in the valley which now im gonna remove and put the valley vent tubes in....Seems weird to me............. Any insight to this would be great!!
 

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Discussion Starter #2
ideas??
 

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Iv'e seen weird oil problems like this with the type of dist. with a slip coller too low??do you have a slip coller? Make sure the dist is not sitting too high to flood the oil from the lifter galley into the valley,,,,just a thought
 

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You need to take the engine apart, and make sure the oil drainbacks are not obstructed, also need to make sure the engine has vent, like the breather that was asked of, also need to make sure you use a performance style oil filter, the oil filter can be a huge restriction. As well the oil pickup could be cracked or broken off completely. These are the ones right off, goodluck. BG
 

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Discussion Starter #7
I got a k&n filter, I have 2 breathers.. I have a screen kit that I put on in the valley and the 1/4" holes I plugged.. I was just gonna pull the intake to check the screens but I can't see how they would be clogged up or anything. As I have the intake out I was gonna put the vent tubes in so it would relief the pressure so the oil will drain. I do not have a slip collar on my dist. Strange problem, if the dip stick tube is pulled out the oil drains fine.. I don't get it.. Running the car it takes a bit till the pressure drops cause most of the oil is collecting up top so it not all at once. But pull the dip stick and it all drains instantly..............................
 

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Nitrous Junky
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I would also take the plugs out and try a set of thiese vents ;)
 

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Your eyes are always the best tool. Remove the manifold and pour 2 quarts of oil in your lifter valley. See how long it takes to drain. If it takes too long than you will need to figure out ways to make it go down quicker. If not remove the valve covers, rockers, push rods and lifters and look in each lifter bore to see if it is over oiling when you prime the pump. If so you will need to start restricting the block in the front and back. Each lifter bore should oil equally. When getting that done install the lifters, push rods and rockers and have someone slowly turn the motor while you prime the pump. You should see drops of oil at the rockers. If your lifters at slotted no need to turn the motor. I ended up with 0, .010, .020 and .050 restictors in my block. You will also see internal restrictions due to garbage being in an oil hole. If that is the case the motor will have to be pulled down.. JMO on what to do.. probably useless information..
 

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If it drains back when you pull the dipstick tube, why not just add a -8 hose from the front of the pass side valve cover down to the mechanical fuel pump block off plate?

Seems like it'd be the simplest fix.
 

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Discussion Starter #13
These are so food idea's! The intake is coming off today, I'll see what I find and see how long it takes for oil to drain back down and go from there.. I like the idea about the valve cover -8 line to the fuel pump block off. You sound like you have done that before, similar problem?? Thanks for the ideas!!!!!!
 

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Discussion Starter #15
So I got the intake off and to my surprise the intake wasn't sealed good, I have oil in the heads and pooled a little on top of the closed valves. You can see oil on the bottom of the intake gasket where it wasn't sealing. So could this cause my problem of the oil not draining back like it should???? Also since the blocked was decked, and the intake is not sealing how would I tell if the block was decked a little off? Could they have decked it a degree off so it was on an angle or so???? ( I've never done it so I don't even know if that's possible) a couple of the intake bolts were looser then they should of been so maybe that's all it was, but the whole intake gasket is wet with oil..
 

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Bracket racer
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No i dont see that causing the issue. Did you look to see how big the openings for the drain back in the valley are? When I did my motor the oil drain back holes had so much casting slag that it was about the size of a dime, if not smaller. Had to grind out and open them up a bunch. I know you have the screens in there. Take them out and see if it makes a difference.
 

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Discussion Starter #17
I gotta stop replying from my phone, words are getting mixed up... HAHA... Anyways the holes are about quarter size maybe a slight bit smaller... See when i pulled the dip stick the oil drained back without a problem.. When i ran the motor and the pressure dropped after about 5min of holding the throttle at 2000-3000 id shut it off and let it sit and about 2min later you would hear the chug, so after a couple times of doing that i pulled the dipstick tube right when i would hear the chug and WOOSH the oil drained fast. So if i shut the car off and pulled the dipstick it would all drain instantly, like putting a hole in the top of a milk jug that is upside down...

Is it possible to deck a block at a slight angle so it would cause the intake not to seal??? How can i make sure the block is decked at the right angle with the heads on??
 

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God help you if someone f'd up the deck. You don't angle the deck on the block, you angle mill the heads.

Sucking oil into the intake from a poor bottom seal will not cause oil drain back issues. It'll just cause it to smoke blue when running, and have a lack of power.

http://www.summitracing.com/parts/CTR-21-952/

There's the part you want.
 

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The only prob you will have with decking the block too much is you make the heads closer together so you would have to cut the intake BUT? you would have to deck the hell out of it ...And that still wouldn't cause your problem.
 

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Bracket racer
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Going crazy. Where in illinois do you live?
 
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