Gen 5 Blazer PCV system (possibly associated with it's oil/air separator system).
Hello Scotty! I am new here. The emission control system on the 2019-forward Chevy Blazer will likely be a very popular topic. I have not yet figured it out. This is a 2019 model, with the 3.6L V6 and AWD with the ZF 9-speed "hybrid" transaxle. This is a direct-injection engine; I am not yet perfectly sure whether it has the extra port injectors. There are 2 little plastic-bodied diaphragm-type PCV valves, one on either valve cover, that are teed common, and connected to a nipple on the "air cleaner output duct" which I will hereafter call the air-case. The air-only intake manifold is physically below the air-case. Nothing that I do makes vacuum register at this nipple, so how can the PCV system operate? The intake manifold vacuum (at the EVAP purge valve, the only vacuum connection to the actual intake) is strong and normal. The suction in front of the (air) throttle body is excellent. The air-case also has a huge PCV system pipe connection from a pipe connected in the engine V area, possibly to that air/oil separator. The 2 described PCV valves are old and probably bad now; I ordered and should pick up 2 new little PCV valves tomorrow morning at a local Chevy dealership. That way worn parts will not be involved. But that has nothing to do with not having any vacuum at that connection nipple! This makes no sense. The air-case nipple is common to the OUTBOARD area of the (flex) duct to the throttle body; I proved that by simply sticking a wire through. The PCV system is supposed to work on "vacuum" from the air cleaner outboard side of the throttle body?? Why is it not connected to an intake manifold vacuum nipple/location like the EVAP? This should not be confused with YouTube videos about drilling out the PCV valves on slightly earlier GM 3.6 setups. These PCV valves are not metal shelled, they are delicate little valves with diaphragms. Could it possibly be desirable to drill a hole in some beefy area of the intake and mount some nipple and change the factory PCV valves connection to that? It could be necessary to reengineer a modern vehicle actually (with the design) still in production? I simply do not understand how something like a PCV system is not connected to the air intake venturi area proximate to the throttle/air vanes, typically at a carburetor/throttle body base. Could they have been trying some kind of "ported" vacuum operation? For PCV? The mileage is 26,450. I changed the (iridium) spark plugs last week and they all looked similar and decent with very slightly worn center electrodes but in-spec gaps. This procedure allowed viewing the inboard-V engine valves, which had more carbon on them then I wanted to see. I did purchase the vehicle used from an in-state dealership about 4 months ago, in seemingly adorable excellent condition; it runs/cooperates very well. I traded in an operatively-insane but also immaculate 2014 Grand Cherokee (that is a long story). The Blazer is a HEAVENLY PLEASURE compared to the Jeep!!!!!!!!!!!! I am prepared to have the engine pulled and those valves properly cleaned, BUT NOT until the PCV system is known to work very well and makes sense! I was about to install a Mishimoto catch can on the 4th. No codes are registering. I have a hunch that the flow has been so poor and intermittent through the PCV valves that they got stuck closed. The described basic service before my ownership is very good, and the engine seems very clean, based upon what I could see when I changed the oil, except for the valve debris. No obvious tailpipe debris emissions exist and it does not feel particularly sooty. Observed instrument panel sensor-obtained engine (actually entire drivetrain) readings are very good. This is just a really weird emissions system. I have changed all of the fluids (and bled the brakes while changing calipers out). The new Blazer is UNBELIVEABLY easy to do basic service on!! The EASIEST is this type of ZF tranny (except that the filters can not be changed during external service)! The Holley RAID Start-Stop Eliminator works SUPERBLY on it!!!!!!!!! This cute little SUV (woodgrain metallic and maple sugar seats) is intended to replace my 81 year old mother's 2007 Focus Wagon (which rotted out at the rocker panel area). She got excellent use from it (I serviced it mechanically like a religion.), NO regrets!! She now needs the power liftgate and powerful air conditioning; the Blazer HAS THAT!! The point is that the Blazer, AMAZINGLY, has VERY conventional operating controls, so she will not become confused by high-tech junk. Vehicles like that are disappearing from new production. I replaced all of the heavily tinted glass possible with the minimal tint type (all GM except rear window Pilkington). Thus we can see through well while driving, and at night! It has an AMAZING Volvo-like front frame that allows VERY easy and safe floor jacking!! A minor exhaust pipe modification allowed the easy and safe use of a 911Motorsport jack extension for rear lifting at the apex of the rear lateral crossmember. Thus if she experienced a flat tire I can run to her with a floor jack (not the dopy factory crank-jack) and change a tire FAST!! It is now the easiest vehicle in the family that I have to get on jack stands!!
The air-case also has a huge PCV system pipe connection from a pipe connected in the engine V area,
three PCV valves? doubtful.
A REVERSE PCV FLOW SYSTEM!! I simply do not believe it.
that's called a breather.
I will see about installing a normally behaving PCV system.
If you don't understand the engineering, then I wouldn't touch it.
Realized gee, I'm pretty much makes garbage these days. Now. I mean I would replace the plastic PCV parts myself and pray it helps because if you still have a problem that means the engine is worn and it's building up too much crankcase pressure from the piston rings being worn because GM uses cheap low tension rings that often don't seal as they wear with age
I hope that engine wear is not involved at such low mileage! I did get the new PCV valves. Testing with a simple hand vacuum pump, they HOLD vacuum when applied to the air-case side! That is totally wrong (backwards) for a traditional PCV arrangement. You can blow air through by MOUTH in the other direction! It was time to reassemble the piping and 2 valves and see what happens. The engine certainly runs lovely. Pulling the pipe (quick-disconnect on hard plastic tube) off of a PCV valve, a piece of paper sticks to the valve's pipe nipple-end. THAT IS VACUUM, VERY WEAK BUT A VACUUM!! My ordinary hand pump gage can't show it. From the ENGINE SIDE!! Jesus Christ, how did they design this system? A REVERSE PCV FLOW SYSTEM!! I simply do not believe it. You can't design engine this way! That is too delicate!! Now what "is to be done"...I.V. Lenin. My guess right now is that the idea is to try to pull "PCV valve" metered air from the air-case down into the heads and into the block so as to get into that "new design" air/oil separator and then back up through that huge pipe to the air-case. That would be GOOFY!! I have a spare air-case and intake manifold on order. I will see about installing a normally behaving PCV system. Will this engine's vacuum tolerate normal (traditional) PCV? Some kind of crankcase access would have to be found, such as an unused factory port, unless some existing location can be shared. We can hope. I might get another air/oil separator or related part and be able to see how to get a normal PCV valve on that. The Mishimoto catch can is on standby. The concern is based upon the carbon on those valves, demonstrating that WHATEVER system this is it did not prevent that on such a low mileage vehicle. This PCV system will likely explode on YouTube with complaints.
The PCV system is supposed to work on "vacuum" f
common misconception.
Strong vacuum closes the PCV valve to prevent crankcase air from entering the intake. Otherwise the engine would run too lean.
When pressure in the intake increases (like during hard acceleration) the valve opens to release pressure generated by the increased blow-by.