I was only thinking that based on what I saw, Intermittent pressure in the CC, you either have the condition you think you have ("ring flutter" which I've never experienced) or, you have a check valve that is getting stuck shut sometimes, or unable to open for some reason. it is interesting you do not run a check valve and have all these issues simultaneously.


Check valves are installed by the factory on all OEM engines. They are called "pcv valves" in the engine when used this way. They perform a couple functions. One is to restrict the amount of air flowing into the intake manifold from the crankcase (not a WOT problem, unrelated feature). The next is to ensure that gasses are able to come out of the crankcase, but not enter the crankcase. As you put it, a minor problem at WOT on an Naturally aspirated engine and unnecessary.

The catch can you are using has a check valve, I am fairly certain. So whether you realize it or not, you have a check valve somewhere. If the check valve clogs shut or jams shut, the crankcase pressure should rise. What I see on your gauge is dramatic, so I am not very confident this is the problem, however it is worth noting.

The other possible explanation is that one of your hoses/plumbing is becoming clogged, squeezed shut, or otherwise inaccessible. To completely diagnose this issue (before yank the motor and without any fancy tests) you might have reduced the PCV system to nothing first- i.e. pull all the lines from the engine, let the crankcase breath directly to the atmosphere and forgo all the excess tubes/catchcan/etc... just to be sure its really the rings going "crazy" and seeing the pressure there without any of that equipment on the car.

 

I see you've already got the motor back out so just some thoughts. One question. Is that a Mighty Mouse catch can?

Got a little confused about the test with the vent tube ran in the car. It kind of sounds like it was blowing all the time? You did the test & you know what it did.

Back to your routing. With a PCV system routed correct I believe you would see some crankcase vacuum. Especially at say 5krpm & the throttle closed. Knowing your car is not stock cammed. At that point I believe you would still see some vacuum. As I said earlier about how your system looked useless. Your clean air line should be routed to the opposite end of the engine. So the vacuum can get in your crankcase & pull the clean air from the opposite side. The vacuum is pulling from the clean air line 6 inches away & your crankcase never sees this vacuum. If you had a bit of crankcase vacuum at high rpm, low/part throttle, maybe that would help the rings to stay sealed & keep from fluttering.

I've heard people disassemble engines, from ring flutter, & everything looks perfect.

Keep us posted.

 

Good catch, it bothered me as well, no vacuum signal means no PCV action from the intake. Something wasn't connected correctly based on that alone it seems , and the lack of a PCV valve suggests a massive pull from the intake manifold on whatever replaced it, which begs the question, what did you replace the OEM pcv valve in the other valve cover (not pictured) with? Where does it run now?

 

Yes.





No, it was only blowing at high RPM and part throttle and then even more when going to WOT from part throttle.






Which line are your referring to as the, "clean air line?"

 

This is an LS6. It never had any line going to the driver's side cover. The driver's side valve cover has no ports from the factory. The PCV valve was in a line between the valley cover and the intake in the factory system. The passenger side valve cover port ran to the throttle body just as it does now in my current system.

 

I agree that its interested that no crankcase vacuum can be seen. However, I don't know how much vacuum should be expected. If its less than 1psi, then not seeing it on these gages is to be expected. Or there is the possibility that my engine is making blow by all the time, enough to equalize the vacuum.

 

Also, I pulled the heads off yesterday. There are minor scuff marks on the cylinder walls of all cylinders. On the inboard and outboard sides of the bores only and only in the middle range of the piston travel. A couple of the scratches are deep enough that I can feel them with my fingernail. I will try to get time to get the pistons out in the next few days.

 

The line off of the throttle body to the top of your passenger valve cover. The vacuum from your manifold would just be drawing fresh/metered air from this line.

I cant say exactly what it would read. I would think at idle maybe a tiny amount. Although you don't have a stock cam so that would make less vacuum at idle. So maybe none. But. At 5k rpm & closed throttle I bet your intake would be pulling over 20 inches at least. From the manifold itself. Not saying you'd see that in the crankcase.

You may have seen these. If you didn't they're pretty cool.




All engines are different but all engines produce blow-by.

One cool thing I noticed with crank case pressure. From switching to bigger headers. With the smaller headers, with my vacuum pump, I would see 11-10' solid under full throttle through the rpm range. With the bigger headers once it gets to a certain rpm the vacuum starts to rise w/rpm. To around 12-13'. This tells me there is now less blow-by on the exhaust stroke from the freer flowing headers.

Anyway. I'm guessing you have the ls6 valley cover port capped off normally? Maybe you could use that valley port as an escape route for pressure. As that would escape most of the pressure before it even got to your valve covers. Maybe a one way valve so it wont suck air. Only blow any pressure out. Bunch of ideas. Don't take it like I'm telling you to do anything. Just trying to help a little.

 

I had a customer with similar issue. Cadillac Escalade with 213000 miles. Turned out the valve covers venting was all clogged up. He put on new covers on and the problem was fixed.

Christian

 

it doesnt rely on the valve cover vents to release pressure as setup...

0/10 troll post.

 

Well that can't be good...............