LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Did I put my catch can on right?

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Old Nov 21, 2006 | 10:24 AM
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Did I put my catch can on right?

Since not many people put catch cans on LT1's I wanted to make sure I put it on right. I ran the line from the pass side valve cover to the catch can, then the line from the catch can to the throttle body.
Old Dec 11, 2006 | 05:15 PM
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As far as I know that is correct, I've been wondering the same thing but haven't found any ltx info, only lsx.
Old Dec 11, 2006 | 05:19 PM
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catchcan for oil or coolant?
Why did you do this? just curious
Old Dec 11, 2006 | 06:08 PM
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Its for oil and yes I think your routing is right, at least thats what I did.
For my contianer I used a air/water air seperator for a air compressor that I got at HF.
Old Dec 11, 2006 | 07:33 PM
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Originally Posted by mdacton
catchcan for oil or coolant?
Why did you do this? just curious
If you saw the inside of an intake manifold or intake ports you would know why. Stock PCV sucks in a ****load of oil into the intake.
Old Dec 11, 2006 | 07:36 PM
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I hooked my up between the PCV and throttle body. Since the PCV is sucking the oil in I though thats where it should go.

Jason
Old Dec 12, 2006 | 02:28 AM
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If possible please post a picture.


Thanks.

Ruben F.
Old Dec 12, 2006 | 04:08 AM
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ttt for reference.

-B
Old Dec 12, 2006 | 07:02 AM
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I don't see where this would do anything.....
I also run an evac system going to the collectors and my pcv is looped to direct manifold vac.

I just don't see where a catch can would do anything...I just don't understand
Old Dec 12, 2006 | 09:24 AM
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I too have a HF oil/air separator between the crankcase and the PCV valve. The vapors that it sucks out of the engine are laden with oil vapors, even in a good engine. Mine separates out about a tablespoon of oil per 100-200 mi. which would otherwise be sucked into the intake manifold and along with the fuel. I can't help but think that the CATs will last longer that way and it keeps the inside of the intake manifold from getting covered with oil.
Old Dec 12, 2006 | 11:12 AM
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Originally Posted by speed_demon24
If you saw the inside of an intake manifold or intake ports you would know why. Stock PCV sucks in a ****load of oil into the intake.
But you didn't put the catch can in the line for the PCV valve. You put it in the vent line that suppies clean, MAF-measured air to the passenger side valve cover, so the vacuum frmo the PCV valve, on the driver's side of the intake can pull the air through the crankcase to remove the harmful vapors.

Yes, in an engine with excessive blowby you can get reverse flow from the valve cover to the throttle body, and the way you hooked up the system will work. Is that the problem you are trying to solve?
Old Dec 12, 2006 | 04:31 PM
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Originally Posted by Injuneer
But you didn't put the catch can in the line for the PCV valve. You put it in the vent line that suppies clean, MAF-measured air to the passenger side valve cover, so the vacuum frmo the PCV valve, on the driver's side of the intake can pull the air through the crankcase to remove the harmful vapors.

Yes, in an engine with excessive blowby you can get reverse flow from the valve cover to the throttle body, and the way you hooked up the system will work. Is that the problem you are trying to solve?

So it pulls air from the bottom of the manifold under the tb to the pcv valve to the tb then to the valve cover? Grr I shoulda known better.
Old Dec 12, 2006 | 04:33 PM
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you must have a lot of blowby to get that much oil
you don't even get that much with a vac. pump
Old Dec 12, 2006 | 05:18 PM
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Originally Posted by speed_demon24
So it pulls air from the bottom of the manifold under the tb to the pcv valve to the tb then to the valve cover? Grr I shoulda known better.
Clean air enters a port in front of the throttle body blades (so it is not subject to vacuum). It flows to the top of the throttle body, under the plastic top cover, out the nipple on the side of the throttle body, and through the hose into the passenger side valve cover.

At that point, it is pulled by vacuum, through the head oil drainback passages, to the crankcase, up through the lifter valley, into slots in the sheet metal cover on the bottom of the intake, through a hole in the bottom of the intake, through a passage in the side of the intake manifold to the PCV valve. The end of the PCV valve that sticks out the side of the manifold has a vacuum applied to it. In the 93/94 engines, that vacuum is provided by a U-shaped tube that bends backwards, and into a vacuum port on the side of the intake manifold. On the 95-97 engines, the vacuum port is on the front of the intake manifold, under the throttle body.

It is not unusual for the flow to be reversed in the line from the passenger valve cover to the throttle body. It can happen at WOT when the rings are subject to maximum blowby, and there is basically no intake manifold vacuum. In that event, there is a baffle in the valve cover that is supposed to keep the oil flipping off the rockers from being entrained in the air leavnig the valve cover. But is isn't very effective.

You may find oil in the rubber hose, and a puddle in the top of the throttle body under the plastic cover. The blades and the intake get coated with oil, which cokes up.

Some people replace the plastic elbow that pokes into the valve cover with a small filter made by Deutsch. That is usually enough to minimize "normal" oil carryover. It gets to be a bigger problem when you have excessive blowby. People with blower motors have to reconnect the system differently, because of the issue of manifold boost.

Your system will "work" with regard to keeping oil out of the throttle body. To accomplish the same thing for the vacuum flow from the PCV valve, you would have to put an oil spearator in the vacuum line from the PCV valve to the intake manifold vacuum connection.
Old Dec 12, 2006 | 05:23 PM
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Great information. How would you recommend the connections be made for a blower motor?



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