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Just be careful to not hydrolock the engine because you are sending Berryman's B12 directly into the ports that run to the intake valves --- it's a very short run.

If it's never been serviced, you may have to attack this more than a few times. But start the engine after a couple of cupsful of B12 so that you don't drop a big glug of the stuff into just 1 or 2 cylinders.

I think using a wire is a good idea - but the best wire I ever found for this type of cleaning is some old mechanical speedometer cable chucked up into a low RPM drill and GENTLY pushed into the port.

I've done that spinning speedo-cable thing many times successfully on plugged Honda EGR systems (our vehicles don't have an EGR system to which I have any knowledge) and it could always earn me lots of money whereas the dealer said they had to replace the manifold - for yards of end-to-end greenies.
 

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I tried the wire and the b12 a couple times but I didn’t know how much was ok to dump in..but my metal “coat hanger” feels like I am hitting metal..like 3 inches into the dirty air side. Could I also dump some b12 in the clean air side?? Is there a possibility that the pcv valve is stuck closed?? Doesn’t seem like it’s gummed up, seems to be blocked off. As far as my knowledge, we do have an egr on the trailblazer but they call it a “secondary air check valve”
 

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I tried the wire and the b12 a couple times but I didn’t know how much was ok to dump in..but my metal “coat hanger” feels like I am hitting metal..like 3 inches into the dirty air side. Could I also dump some b12 in the clean air side?? Is there a possibility that the pcv valve is stuck closed?? Doesn’t seem like it’s gummed up, seems to be blocked off. As far as my knowledge, we do have an egr on the trailblazer but they call it a “secondary air check valve”
Just be careful to not hydrolock the engine because you are sending Berryman's B12 directly into the ports that run to the intake valves --- it's a very short run.

If it's never been serviced, you may have to attack this more than a few times. But start the engine after a couple of cupsful of B12 so that you don't drop a big glug of the stuff into just 1 or 2 cylinders.

I think using a wire is a good idea - but the best wire I ever found for this type of cleaning is some old mechanical speedometer cable chucked up into a low RPM drill and GENTLY pushed into the port.

I've done that spinning speedo-cable thing many times successfully on plugged Honda EGR systems (our vehicles don't have an EGR system to which I have any knowledge) and it could always earn me lots of money whereas the dealer said they had to replace the manifold - for yards of end-to-end greenies.
 

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I also read somewhere that the pcv is not serviceable, and to change it you have to change a rocker arm cover? But I can’t seem to find many details and I don’t know what that means..
 

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Just as a reminder, there is no PCV valve in this engine's PCV system. There is a flow restrictor instead of a spring loaded valve we are used to seeing.

Also, there is no EGR valve. An EGR valve allows the flow of exhaust gases into the combustion chamber in order to drop the temperature to minimize the formation of NOx compounds.

Also, the Secondary Air System and it's Check Valve perform a similar, but completely different function. It injects air into the exhaust stream when the engine is cold in an effort to assist the catalytic convertor in minimizing the amount of unburned hydrocarbons (fuel from incomplete combustion) that pass through the exhaust system and released into the air when the system is cold (below a specified temperature).

As far as introducing B-12 into the clean side air, I do not know if that would do any good.

Regarding the changing of the rocker arm cover because there is no serviceable PCV system, well, you are actually servicing the PCV system so I do not believe you need to go down that path at this time. I'll let Ravalli Surfer have the final word on this aspect.

Just as an FYI - some V8 engines (like the 5.3 L V8) that were manufactured in the last 10 -15 years did not have a PCV valve either. They also had a fixed orifice located in one of the valve covers. Some of the early ones would gunk up leading to a significant increase in oil consumption, so GM came out with a redesigned valve cover using extra baffles in the area of the fixed orifice in order to minimize the plugging of the fixed orifice and related oil consumption.

Hope this helps.

I would say that if you can, shine a light into the opening into the engine where the flow restrictor is located and see if you can get an eyeball view to evaluate if there is more gunk left to dissolve with B-12 and rodded out with the wire.
 

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The flow restrictor is located there in that tube where you have been putting the B-12 and your wire into.

You are welcome and good luck!
 

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Well --- it did --- but it won't stick for a while yet - maybe a few more weeks and IF the bookbinders at Poor Richard's and my knee concur, it will be a great big white out for a few weeks - not unlike the snowstorm we all heard about that happened "last time in aught-six" which really implies.1806, not 2006.
 

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The flow restrictor is located there in that tube where you have been putting the B-12 and your wire into.

You are welcome and good luck!
Actually - the flow restrictor is the nipple on the valve cover that most persons think is the vent into the sound box. It's the other way around --- in that the restriction is in that nipple in the form of a hole of "x" dimension that is designed to keep the in-flow of clean air into the valve cover - and therefor also into the crankcase - under a vacuum at all times.

Herein lies a conceptual problem in that the MAP "reads" the available vacuum inside the plenum, past the throttle butterfly - in that --- among it's OTHER duties - is to report the amount of vacuum in the plenum to the 'puter.

The 'puter then will keep the electronic throttle motor from going WOT unless there's sufficient negative value inside the plenum (and therefore: also the crankcase) to keep taking fumes and byproducts of combustion that leak past the rings - etc - and channel them into the intake runners just before the intake valves - then into the combustion chambers - where they are subject to re-combustion and then to exit the exhaust system.

A lo-o-ng sentence (above) fer sure - but there's a concept here that's interesting and kinda marvelous at the same time -- IF IT IS IN WORKING ORDER.

MOST of our 4.2s PCV Systems suffer from lack of maintenance - even denial that a PCV system even exists on these Atlas marvels - and then the brown baby poop gets into the sound chamber, collects on the 710 cap and inside the dipstick tube.

These (^) are all harbingers of a failure to flow the vapors out of the crankcase well - or even not at all in severe cases.

Throttle bodies are not inherently dirty and need cleaning all the time ... if the PCV System is actually working.

This is pure and simple an operator failure.
 

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Thank you for the explanation and location correction. I stand corrected!
 

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Hm. I tend to SIT when corrected - but that's a choice-thing.

No - the flow of the system - fraught with misunderstandings and mystery - kinda-don't really lend itself to understanding on the first twenty or thirty go-throughs.

It took me a bit of naval-peering and engineering-understanding it too - but having been --- well, you know my credentials - PCVs aren't too mysterious to me ------ as organic chemistry isn't to you.

I applaud your abilities and adroit(*) knowledge.

(* Dexterous in the use of the hands or in the exercise of the mental faculties; exhibiting skill and readiness in avoiding danger or escaping difficulty; ready in invention or execution; -- applied to persons and to their acts )
 
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