HOW TO DO AN ADVANCED SEARCH.

Mon Jul 08, 2013 3:56 pm by Admin


For the benefit of 944Hybrids users there are two search functions available for you to use.
The purpose of this sticky is to explain the "Advanced Search" function because it is much more powerful and is the best choice when researching information.

When you log on to the site a list of options is shown in a line at the top of the page. One option is labelled "Search", use this option (NOT the search box lower down on the right).

After you click on the upper search option, a drop down box appears. At the bottom of this box is a radio button marked "Advanced …

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Oil in the intake manifold and throttle body

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Oil in the intake manifold and throttle body

Post  Lemming on Sun Nov 03, 2013 12:15 pm

Ok, I'm consuming oil.  I know that I need to replace my valve stem seals as the car smokes on startup after running hard.  Also a bit of smoke on deceleration.  What I cannot understand is why I have oil in the throttle body, it will pool just below the blade.  

Pic below is my current setup.  I have the LS6 valley cover that goes into a catch can and then in to manifold.  The two ports at the back of the heads are tied together.  The front passenger side vent goes to a catch can, but little is collected.  

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Re: Oil in the intake manifold and throttle body

Post  xschop on Sun Nov 03, 2013 1:03 pm

What is the black can? Looks like the shortest circuit is taken to the throttle body from pass side.
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Re: Oil in the intake manifold and throttle body

Post  Lemming on Sun Nov 03, 2013 1:51 pm

That's a saicho micho (sp?) catch can.  Air is pulled out of the LS6 valley cover, into the can, and then into the front of the manifold. At the end of a busy track day, it will catch a few tablespoons of oil.  The vent on the throttle body is capped off.
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Re: Oil in the intake manifold and throttle body

Post  944convert on Sun Nov 03, 2013 3:09 pm

I didn't understand the plumbing until I look at this:

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Re: Oil in the intake manifold and throttle body

Post  Lemming on Sun Nov 03, 2013 3:26 pm

944convert wrote:I didn't understand the plumbing until I look at this:

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Yep, that's how it's attached.
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Re: Oil in the intake manifold and throttle body

Post  docwyte on Mon Nov 04, 2013 8:42 am

You sure it's just the valve stem seals? My car does the same thing, but smokes worse than yours. I replaced all the cam seals with no improvement. No oil on my throttle body/intake mani tho.

Car is about to get wet/dry compression tests and leakdowns again. I suspect bad rings. Plan is to pull the motor to rering/bearing it and install LS6 heads at the same time...

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Re: Oil in the intake manifold and throttle body

Post  Lemming on Mon Nov 04, 2013 9:20 am

I did rod bearings and rings last Feb? Guess it wouldn't hurt to do a compression leak down test.
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Re: Oil in the intake manifold and throttle body

Post  docwyte on Mon Nov 04, 2013 9:23 am

My car smokes pretty good on startup and like a mofo on decel. I'm burning oil and you can smell it.

I know my exhaust valve guides have some play, but smoking on decel is almost always rings...

Just wish I'd known this last off season as I almost had the motor completely out of the car then, could've saved quite a bit of cash...

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Re: Oil in the intake manifold and throttle body

Post  P911P951 on Mon Nov 04, 2013 6:03 pm

Lemming, not sure this has anything to do with your problem, but based on your description of what is hooked where on the catch can system, it is my understanding that the left passenger front valve cover vent is suppose to connect to a metered air source ahead of the TB as an input to the crank case. You appear to have it going to a catch plastic bottle which means your pulling unmetered air from the valley port on through the catch system to the intake. I think you might be right about the valve seals but one thought is you have lost some neutral balance in the crank case and are actually causing suction from the valley tray hence more oil. You also may be causing yourself a lean condition because of the unmetered air. I know you have done a ton of tuning based on your original build posts and maybe you out tuned it, if that is a term. Just an observation. Jack

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Re: Oil in the intake manifold and throttle body

Post  Lemming on Mon Nov 04, 2013 6:35 pm

Jack,

For most of the build I have been running from the front of the passenger valve cover to the throttle body vent as you describe. After I found oil at the base of the throttle blade, I assumed it was entering from the line (which did not have a catch can set up on it). Thus, while at NOLA last month it was suggested that I dump the line to an open catch can, so I did. Since it did not eliminate the oil in the throttle body, that cannot be the cause, but nor does it seem to have any affect on my A/F ratios while on track. I pulled a few plugs this past weekend to check and they looked fine. I'll likely install another catch can on that vent line and reinstall (but I'm not sure it does much to be honest).

The oil much be blowing outward from the exhaust manifold under deceleration, oil is then hitting the throttle blade and pooling at the base. Not sure how else it could get there with the current setup.
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Re: Oil in the intake manifold and throttle body

Post  P911P951 on Mon Nov 04, 2013 7:28 pm

I see.. Hey, maybe vent it all to the plastic bottle and see what you are really capturing. Block off the TB port too. That eliminates it coming from the intake side and if it still is bad you are on track for valve seals. If it the bottle gets filled your looking at rings (again I think I read).

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Re: Oil in the intake manifold and throttle body

Post  Rich L. on Mon Nov 04, 2013 11:59 pm

Interesting that you've linked the two vents on the back of the heads. I've generally seen that people plug/cap those vents when going to an LS6 valley cover.

For my setup, I have a dual Saikou Michi can. The clean side from the front of the passenger head to the throttle body catches nothing. The dirty side from the back of both heads collects a pint in 30 minutes of running. I have to drain it a couple times on a busy track day. But the car doesn't smoke on startup or overrun and I've not noticed oil in the throttle body.

Rich
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Re: Oil in the intake manifold and throttle body

Post  Lemming on Tue Nov 05, 2013 7:09 am

P911P951 wrote:I see..  Hey, maybe vent it all to the plastic bottle and see what you are really capturing.  Block off the TB port too.  That eliminates it coming from the intake side and if it still is bad you are on track for valve seals.  If it the bottle gets filled your looking at rings (again I think I read).
Tried that, without negative pressure to the valley cover I blow the dipstick out.
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Re: Oil in the intake manifold and throttle body

Post  Lemming on Tue Nov 05, 2013 7:11 am

Rich L. wrote:Interesting that you've linked the two vents on the back of the heads. I've generally seen that people plug/cap those vents when going to an LS6 valley cover.

I've seen it done both way, not sure that it really makes a difference.
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Re: Oil in the intake manifold and throttle body

Post  money pit 951 on Tue Nov 05, 2013 9:35 am

Lemming -
Some thoughts:

All those lines are too small for a track going engine to vent pressure. It's fine for a street car but for a race engine there just isn't enough cross sectional area for the pressure - esp as your engine wears and more pressure slips out. Remember that any pressure inside the case will float the rings and create more case pressure and drop compression. All not good for HP... This is why a dry sump usually give a nice HP bump besides helping with oil issues. But also if the pressure can't get out it's going to find some way out and that might be through the valve guides, taking oil with it.

Being a track car, I would pull all the vents going back into the intake. There's just no need for them going there. You don't want any oil or oil mist through your intake nor do you want the exhaust gas/case pressure going into your intake. It's exhaust gas so there's no oxygen in it for a burn so it's just displacing air with O2 that is needed to make HP!

All that said, a suggestion would be to follow what I've done. I was also having pressure issues and blow by in the case and and basically the same setup as you. I removed all the small vent lines and welded in two AN10 bungs (AN8 would prob also work fine and hoses are smaller to deal with) onto the valve covers. Bought a small catch can vented to the atmosphere and capped the feeds into the intake. Not only does the engine run better with almost zero oil blow by, but it was a 4HP boost on the dyno (yes, actual dyno runs since I own a dyno). In the last two events I did (full day events so 5-6 hours of running) almost no oil was collected. I think the vent lines are now so big that the velocity in them is low so the oil drops out and runs back into the engine rather than being carried through as the smaller lines would.

My valve cover setup
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Sorry if this comes off as 'preachy' - not my intent.
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Re: Oil in the intake manifold and throttle body

Post  acorad on Tue Nov 05, 2013 11:48 am

Ya, from my research and training, unless the catch cans are mega huge, they won't really help much.

You need the velocity of the air carrying the oil vapor/oil droplets/whatever to slow down radically in order for gravity to be able pull the oil out.

The slower the air is moving, and the longer it's moving that slow, the more oil will get pulled out.

From what I've seen, none of the catch cans are even close to being large enough to slow down the air enough and long enough to be anywhere near 100% effective. They'll catch some oil, but most continues through the catch cans into your intake.

For a race car, I'd simply vent the valve covers or valley cover to the atmosphere, or some similar setup like money pit outlined.

I'd be sure to monitor the oil regularly as it might degrade somewhat faster from blowby/etc sitting longer in the case because it's not being sucked out by the intake manifold anymore.
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Re: Oil in the intake manifold and throttle body

Post  money pit 951 on Tue Nov 05, 2013 1:36 pm

Acorad - I agree, but where I think we're blurring lines (probably with what names we're using) is the catch can is really just the last attempt at trying to catch the oil in the air. The air/oil separator is really what should be doing that. Do do this, it's really just surface area that's needed for the suspended oil to bond to something, but as you said needs to be is slow moving air. For the most part, that's usually some piece of mesh/steel wool. It allows the air to pass, but the oil sticks to the metal and eventually collects enough to drip back. I've seem some catch cans with the separator as well but they're usually as you said just cans with some fittings.

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Re: Oil in the intake manifold and throttle body

Post  acorad on Tue Nov 05, 2013 4:19 pm

Money pit, yes, a mesh or screen of some sort can increase the efficiency of the separator but the main point is that they really are not nearly as effective on the LS engines as many people think.
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Re: Oil in the intake manifold and throttle body

Post  Lemming on Tue Nov 05, 2013 9:13 pm

All good suggestions. I agree that a dry sump is the way to go, I just don't want to keep dumping money into this car. MP, I like the idea of larger lines, are you running a LS6 valley cover and dumping that to a vented can as well?
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Re: Oil in the intake manifold and throttle body

Post  money pit 951 on Tue Nov 05, 2013 10:18 pm

Lemming wrote:All good suggestions.  I agree that a dry sump is the way to go, I just don't want to keep dumping money into this car.  MP, I like the idea of larger lines, are you running a LS6 valley cover and dumping that to a vented can as well?
Yes, I have the LS6 valley cover but its from other attempts at venting the engine. It's doing nothing right now and would put the stock cover on if I still had it. The pressure is coming out of the AN10 lines since they pose much less restriction.

Would be happy to post more pictures of my setup if you want.


BTW, if you're welding the Al AN fittings to the valve covers don't expect a pretty weld. It's oil soaked Al so it's almost impossible to get it clean for the weld. But an ugly weld is still effective in this case.
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Re: Oil in the intake manifold and throttle body

Post  Lemming on Tue Nov 05, 2013 10:24 pm

money pit 951 wrote:
Would be happy to post more pictures of my setup if you want.
Pics would be great!
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Re: Oil in the intake manifold and throttle body

Post  docwyte on Wed Nov 06, 2013 8:31 am

Turns out I'm dealing with the same problem. Compression tests (wet and dry) came back good, they didn't change and I'm making good compression.

Things are now pointing at how I have the crankcase ventilating. I'm going to swap a few things around, clean out my intake and go from there...

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Re: Oil in the intake manifold and throttle body

Post  Lemming on Wed Nov 06, 2013 8:33 am

docwyte wrote:Turns out I'm dealing with the same problem.  Compression tests (wet and dry) came back good, they didn't change and I'm making good compression.

Things are now pointing at how I have the crankcase ventilating.  I'm going to swap a few things around, clean out my intake and go from there...
Please document what you do and the results, we need to get out setups working better!
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Re: Oil in the intake manifold and throttle body

Post  docwyte on Wed Nov 06, 2013 8:41 am

Right now my setup is LS6 Valley Cover, with the Elite Engineering catch can, I'm also venting off both ports on the passenger head, heading into the catch can, then PCV, then one port just past the air filter and another into the intake manifold.

The local CMC LS engine builder has suggested that I block the ports on the valve cover, just vent off the LS6 valley cover and block the other port just past my air filter. So go from the LS6 valley cover to the catch can, then to the PCV valve, then into the intake manifold...

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Re: Oil in the intake manifold and throttle body

Post  xschop on Wed Nov 06, 2013 8:44 am

Hey Tim, on the 5.3 swap I used a PCV1009 valve that fixed any oil consumption. On my LS1 I simply added one to each valve cover vented to atm. I followed what my friend did on his C5 which fixed his oil consumption.
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Re: Oil in the intake manifold and throttle body

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