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GM 3.6 VVT

Air through the crankcase would have to be getting there either past the rings (did they lose their tempering, perhaps?) or through the piston due to a crack/hole. The only other route would be through a crack in the combustion chamber of the head up into the valvetrain area. Mysterious, to say the least.
 
Get well soon for you Mom!

Is there a path with a blown head gasket from the cylinder to the crankcase without going through coolant? This would be a warped head or block possibility.

You mentioned the blowby condition from the compressed air test before teardown ... Did anything stand out as a cause you attempted to correct?

A warped cylinder comes to mind as a possibility.

Just one cylinder low on compression? It should still fire on the rest if it's getting good fuel.

Bent valves do risk piston damage, but, I think you would have seen it clearly.
 
I worked on a few of these engines as well.A guy brought a 2010 enclave 3.6 my way a couple years ago with bad multiple misfires.Local GM dealer said all the ignition coils were breaking down.It had new acdelco iridium plugs just installed.I checked the oil and it was about 3 quarts low and pretty dirty.Being a VVT engine the oil has to be clean and at the proper level for it to perform properly.

So I had the owner pick up a can of liquimoly engine flush with new oil and filter.I did the flush and the oil change and no misfires ever came back.He left my place and got about 100ft when the misfires disappeared altogether.He literally cried.Thats how happy he was afterward.Because he knew buying ignition coils weren’t cheap not to mention paying a shop at $130hr to install them is not easy either when one doesn’t have much money.Bottom line is it didn’t need coils but just a basic oil change to fix the misfire.

No problems came back until about last year when one spark plug failed.I did another engine flush on it to clean the gunk out of the VVT system and it had no issues since then.
 
ak diesel driver said:
Engine is back out, started about 11 and finished about 2. Probably had 45 minutes worth of interruptions. Getting faster. Only thing I didn't have to do was drain antifreeze as I hadn't filled it yet.
Click to expand...

The aftermarket timing sets are something one definitely needs to watch out for.I did a head gasket job on a 12 dodge 3.6 pentastar engine last winter.No cabin heat because the forward head was warped.I yanked both heads and had them gone through at the machine shop.

I ordered the SKP brand master timing chain set from RA with new head bolts,etc.I had it altogether with the exception of the valve covers and timing cover.I attempted to rotate the engine a few revolutions before I closed it up and it wouldn’t rotate.I then loosened the idler gear bolt a couple turns and the engine rotated perfectly.So it turns out the idler gear sprocket in the SKP kit was about .050” thicker than the original sprocket.I went to a local shop and had the gear machined in a lathe to enable me to use it.So it also pays to rotate an engine over a few turns before it’s all closed up.

The Audi 2.0 tsfi engine is another beast you need to be careful with.I did a timing chain set replacement last summer on that one.
 
Well finally getting back to this got the engine off the subframe and onto an engine stand. As I was loosening the head bolts on the left bank the phaser on the intake suddenly made a noise like a spring unwinding. Hmmm. Bad new part??? Already had all the timing stuff removed.
 
ak diesel driver said:
Inspecting the cylinders closely and I find thisView attachment 78851
Some discoloration and then this View attachment 78852
Actually shows up better in the pics then in person. Can't feel the marks though
Click to expand...
Unless the piston is much worse than the cylinder. 🤷‍♂️
I’m not seeing in tje first pic what You is intending to show.
My eyes aint so good though. Go in Monday for a fix.
 
If the scratches in the cylinder wall can not be caught with a fingernail, if it was my engine, use some 400 sanding paper and dress up that area, get a new piston and figure out why that gapless ring seized within its groove.
That one piston alone could cause a case of blowby.
Inspect the rest of the pistons and rings too. Make sure that all of the rings will feely rotate within their grooves.
 
The shiny spot may be a high spot in a warped cylinder or the stuck ring was the thrust bearing for the piston.

IMO the rings that were stuck are destroyed, but, I would ask Total Seal about it with the pictures. My concern is the cylinder scratches also scratched the ring to cylinder sealing surfaces.
 
WarWagon said:
The shiny spot may be a high spot in a warped cylinder or the stuck ring was the thrust bearing for the piston.

IMO the rings that were stuck are destroyed, but, I would ask Total Seal about it with the pictures. My concern is the cylinder scratches also scratched the ring to cylinder sealing surfaces.
Click to expand...
Yup, I would not reuse any of those rings.
Only check them to see if any more is sticking, and, try to see why that one cylinder ring was sticking.
I would not even use that piston.
 
So a little update. Finished putting the bottom end back together just now. Thought I'd post what I learned about gapless rings. In the past I always just sent them the second ring and I got them back in a package without any literature. When I was contacting them this time I got on their website to get their number and got noticing the pictures they showed of gapless rings, and the pictures all had the ring installed in a certain way. So while I was on the phone with the tech I asked him if it matters which way they go in? Oh yes he says if you put them in the other way it'll suck oil out of the crankcase and you'll use oil. I gave him a little piece of my mind and told him they needed to send literature. Kind of a big deal IMO. So you guessed it I had them in upside-down. Explains the oil consumption and the rings being stuck in the groove.20230228_151740.jpg20230228_151801.jpg20230228_151808.jpg
 
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