Finally Jumped on the Oil Catch Can Bandwagon

[Jason in DLH]

Here’s the updated valve cover:

https://www.rockauto.com/en/parts/general+motors,12570427,valve+cover,5772

I haven’t done much research on the deflector for the AFM because I don’t plan on doing that. Maybe someone will chime in for that...

I have officially joined the oil catch can group.

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Glad to have you in the bandwagon!

 

[Jason in DLH]

You're preaching to the choir here, buddy haha.

What you have said I have pretty much said to my husband, but the "what ifs" that I always come up with do not concern him as much.

But maybe if it comes from someone else, such as this forum, he will listen

Been married for 22 years and the honey-do list has always been difficult because he works such long hard hours and if it's not urgent (ie not a crisis) hard to get it to be prioritized. He is so stressed and busy in planning at work as a project manager for a Hazmat company that he doesn't have the mental energy and/or time to do a lot of these things that he thinks I'm just worrying about (case in point- He was up at 3:00 a.m. this morning to prepare for a Saturday job today, after already working 45 hours this week) The poor man needs to get some well-deserved rest on his time off!

Seriously if my arms were longer and I had more skill and experience, I would just do it myself! Or in the past when he is too busy or tired sometimes he says go ahead and pay someone else to do it.

We are both pretty frugal but if this is going to be a relatively inexpensive mechanic bill to prevent a potentially really expensive issue, I might be pushing for that. Wish me luck

Good luck! I was only trying to help you come up with some ideas you may have overlooked.

I find by jacking the rear end up as high as possible (with really good tire blocks in the front of course) that it helps significantly getting at/working on the engine. I have a really bad shoulder that doesn’t allow any reach, so the aforementioned really helps.

And again, good luck!

 

[Jason in DLH]

I have officially joined the oil catch can group.

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I can’t remember...do you have the updated rocker cover?

I’ll be interested to see how much oil you catch compared to my engine.

 

[iamdub]

I understood the spray from the holes in the AFM relief valve squirting out horizontally into the bottom of the block and I also got the way the down rev valve cover got so much oil into the channel leading to the PCV and ultimately into the intake.

What puzzled me, and still puzzles me I guess to some degree, is the “when”. Is it open and spraying all the time the engine is in the higher RPM range, if the oil pressure is above 55 PSI? I suspect it does, regardless of the status of the AFM solenoids.

I frankly never really focused on my OP when in tow mode hauling up some of those big inclines (if I fixated on anything, it probably was the transmission temp) but given the fact that my engine always seemed strong in the OP area and the first 60K or so miles of driving was with a big old tandem axle enclosed trailer in tow, I guess maybe my AFM pressure relief valve was spraying a great deal of the time (versus just when coming out of V4 mode).

I think maybe what really convinced me my stuck oil rings were from oil ingested from the PCV was when I saw the spark plug in number 7, when the first diagnosis was started on my oil consumption. It just made squirts from the AFM relief valve shooting a brief squirt up into the bottom of the cylinder bore seem unlikely to be the source of the stuck rings.

Thinking about a steady 55+ PSI stream of oil from that AFM relief valve up into the bottom of a cylinder bore inline with the jet, makes believing the AFM deflector might actually have done something in the grand scheme of things.

I suspect I will actually never know for sure.

I see what you're questioning now!

No, the valve isn't just a second one that is simultaneously tied into the system along with the relief valve in the oil pump. Look at it as the AFM oil system being separate from the engine oil system. Through the series of solenoids in the VLOM, the AFM system and lifters are pumped up with the engine's oil pressure (that IS regulated by the relief in the oil pump), but then they are blocked off from it (by the solenoids in the VLOM) to stay pumped up. So, the lifters and AFM system are now pressurized and isolated from the main engine oil system. When AFM activates, the lifters need to be drained so they can collapse to shut off operation of those cylinders. The AFM solenoids in the VLOM open, releasing the oil pressure from the lifters. They collapse and the pressurized oil is directed from them to the relief valve in the oil pan. All the while the main engine oil pressure is remaining steady. So, the valve is only spraying when AFM activates and bleeds down the lifters. It is in no way connected to the engine's primary oil system.

Besides adding to the oily mist in the PCV system, the oil sprays on the bottom of the #7 cylinder, where it works its way up and gets burned, etc. leading to the carbon caking that sticks the rings, accelerates cylinder wear, etc.

 

[iamdub]

Surprised it took GM that long in this generation to realize this. Valve covers have had baffeld pcv/oil fill ports since forever to keep the spray from the pushrods/rockers out

Sent from my SM-G930V using Tapatalk

Yes, but the PCV airflow is strong with the LS. Back in the day, you just needed a breather on the valve covers. Then, they made one breather in and the other breathe out, but it was mostly natural currents from the crankcase pressures. Now, they're using intake manifold vacuum to sort of "reverse supercharge" the evacuation of the PCV system. This increases the system's efficiency while giving it a way to be monitored (through the MAP sensor), keeping it a closed system to further satisfy the EPA.

 

[iamdub]

So based on this thread, if I understand it correctly, since I don't know if my Tahoe has the new valve cover, putting in the catch can MAY help me alleviate some of the damage if it's the old one and/or determine if it is (besides taking it off to look-wish they put something on the new ones that is identifiable without taking it apart).

Or do folks who have done the AFM delete/new valve cover STILL get oil/gunk in the can and I won't know from a catch can's contents?

Wish I had more experience with actual work under the hood- I'd take it apart just to look (and replace if needed) even though I'm not showing any signs now at 88k.

Drives my husband nuts thinking I'm borrowing trouble for tomorrow and I prefer to think of it as "prevention-minded" or "forward-thinking". Besides, you'd think the idea that I could tell him "I told you so" if we ever had issues would be enough incentive for him to do it for me now haha

I'm with you and if I ever had issues, it will drive me nuts with the wanting to know if ABC caused XYZ.

The catch can is to catch what passes through the rocker ("valve") cover. The old cover passed more due to the baffle design. If yours is passing a lot, then your can would catch a lot and you'll have to drain it more frequently. If it's passing a little, then your can will catch a little and won't require frequent drainings.

Disabling or deleting AFM removes one factor of oil consumption- the burning of it from the #7 cylinder and the burning of it from all cylinders when the oily mist is dispersed into the top of the intake manifold via the factory PCV system routing.

It's best just to keep it in the engine in the first place, and that's done by getting the updated cover. You've already eliminated the burning of it from the AFM relief valve by disabling AFM. All that's left is the cover and a cheap catch can to top off the proactive measures.

A novice taking their time can have the cover off in half an hour. If it's the updated one, simply do everything you just did in reverse and be done and satisfied while only consuming one hour of your time. If it's the old one, simply do everything you just did in reverse so you can continue to drive it until you acquire the updated cover. You can buy new or, if you have any good salvage yards around you that would have GMT900 vehicles, you could get an updated one for cheap. Even if it's a pre-2010 truck, it might have been updated, so it's worth a check. This is the casual Saturday junkyard digging approach. Your interests and/or time may be more valuable and just having a new one put on your doorstep is more befitting.

Say you did have to buy a new cover for ~$100. That, plus ~$60 for the AFM disable (just estimating- how much was it total with shipping?) plus a $40 catch can (rounding up for hoses and bracket materials) is $200 you invested to save $4,000. And your Gen4 engine is now almost as reliable as the Gen3. I say almost since the AFM components are still in the engine. But, they're less likely to do any harm, and for a long time.

 

[iamdub]

I believe most cans use filters in them that will work. I did check my JLT and it does have a filter on the outlet side which appears to be working well with the amount of crud I caught during only a 20 minute drive.

Here’s a great video about the different types catch cans (with data showing they actually work)...

I haven't watched that video yet, but the one in the middle with the $100 price over it is ridiculous. That's the $15-$25 one on Amazon.

 

[Jimmyy]

Original owner very well may have had the updated cover installed, and that is why I wish I had an xray machine!

https://www.amazon.com/Suchinm---En...id=1616866260&sprefix=USB+endo,aps,196&sr=8-2

 

[iamdub]

I think the premium catch can makers would tell you the optimum air/oil separator is made of unobtanium, with superconductor cooling towers to eliminate restrictions and maximize oil and contaminant separation. Someone else might tell you (kind of like a member recently quipped), all you need is a beer can stuffed with steel wool, or some such levity.

I went the semi premium route partly because they have a reputation and with YouTube any number of tuners/racers who will call them out if their claims are suspect. I personally think someone with your handiness level could experiment on their own and get to the optimum answer pretty quickly.

In the end, at the rpm levels (at least some of us ) are running at, you are going to catch a bunch of the crud getting pumped out by condensation as it passes through the hose and trickles into the can on the input fitting. Anything you do above that has got to help, maybe until you get to the point where you are restricting airflow. As I understand it, that is the value add of the premium vendors pitch.

The oily air going through it doesn't give a shit what the can is made of or whose name is laser engraved or written in Sharpie on the outside. All that matters is that it is forced to go through an efficient coalescing medium before continuing on into the intake. You can use a ****** baffle, such as a metal plate with a bunch of 1/16" holes in it, placed inside of a 7068 aluminum tank with a performance brand logo laser-etched into its anodized surface, secure it with a precision machined bracket and plumb it with AN fittings on 3000psi braided hoses and sell it for a few hundred bucks and it'll be great for oohs and aahs at the next Cars and Coffee meet. Or, you can use a combination of sintered bronze, poly matala and baffle plate mediums inside of a basic machined aluminum can and actually perform a function for as little as $15.

There is a huge gray area between the extremes to satisfy virtually anyone's desires. Want good function and can fab up your own mounts, you'll get off the cheapest. Want something that has a pre-fabbed bracket, just spend a little more. Want something worthy of being next to your $8,000 supercharger setup? Expect to spend a good bit more. Just know what you're getting as price doesn't equate to performance.

I agree with the semi-premium route. I can't think of anyone that'd make their own from a beer can. Except maybe for @89Suburban. Even then, he'd do it just to see if it could be done and for teh lulz.

 

[iamdub]

Yes, that was me...probably driven under 1000 since purchasing at 87k (have to check bill of sale to get exact) and seems to not be losing any.

I'm beginning to wonder if original owner did have it done... if the guy wasn't hurting for money and went in for an oil change and was losing oil on his relatively new engine and they had the service bulletin, it's very possible that he just did it. But see, with the way my mind works I NEED to know lol

The way you drive (amount of load on the engine) has a lot to do with it. Not running it hard goes a long way to reducing the amount of oil in the PCV system.

One thing you could check just to get an idea of the depth of preventative maintenance or repair, is to read the date on the VLOM to see if it is newer. If that had been updated, then there's a possibility that other PM items, particularly a simple TSB item such as the updated rocker cover, could've been addressed. The VLOM on my '08 was dated 2014 and mine had the updated one. No, an updated VLOM doesn't automatically equate to having the updated cover. It's just a quick and easy way to see what, if anything has been done to your engine.


Referencing the image below, the VLOM is the plate on the top center of the engine block, between the heads. It has all the gnarly castings in it. It'd be under the arch of the intake manifold. You'll have to look at it from an angle as the throttle body is in the center. Use a good flashlight and look on the front top edge of the VLOM for a series of numbers. You should see a date code.

*EDIT* In case that image above isn't showing, here's another, but crappier image: