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GM 3.6 VVT

Well you can uncross your fingers Will. Put air in the cylinders to verify where the compression was going and it appears that every single intake valve is bent. Worse yet 2 cylinders leaked into the crankcase pretty badly. So I guess it's going to get completely torn down. I had to walk away for today......
 
ak diesel driver said:
@Rockabillyrat do you know if the phasers can move enough to cause valve contact? Near as I can tell it appeared to be in time still
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They shouldn't be able to move enough to make valve contact. It would have to physically jump time or the phaser would have to some how fail to allow too much movement to bend the valves. 99% of time I see broken timing chain guides on these. I actually have one in my garage now for a friend im doing on the side.
 
Acts like overspeed from slipping transmission etc. Rod bearing is a maybe on overspeed, but, bent valves if you don't see a cause is too much RPM.
 
So been thinking about this engine. Came to the conclusion that in order to bend valves on both banks that the problem would have to be in the primary chain area. That got me to thinking maybe the crank key had sheared.IMG_20221126_160745.jpg
Looks pretty good to me. So then I got talking to my mechanic buddy and he seemed to think most engines without timing marks have the keyway straight up. Checked that but obviously that's not correct for this engine. So I found a YouTube video of a guy who was doing one of those engines and he said that when the dots on the crank gear and the dot on the oil pump line up that that was TDC. This is what I have IMG_20221126_165442.jpg
So now I need to verify that that is indeed correct. My gut is telling me that this is where the issue is. In order for that to be right it would have to have a broken crank.
 
The colored links line up with the dots on the gears. They won't line up once you spin the engine over a few times. So you have to get it right the first time. You can spin the engine over until the colored link lines up with the crank gear dot and check the rest of the alignment. But it could take several revolutions for it to line back up again. And the secondary chains might not line up the colored links at the same time as the primary chain.

Very rarely does the crank keyway go in the 12 o'clock position when setting timing on modern engines. Its all alignment links and dots and sometimes specific tools to hold the gears because they don't use any keyways (ford) and it's impossible to do the job without the crank and cam holders. We had to buy alot of special tools for all these new engines at the shop

Here is a screen shot from Mitchell on the alignment marks for that engine. Might not be the best quality because I can't download pictures from their website unfortunately. If that doesn't work I can print it and take a picture of that.
Screenshot_20221126-233526_Chrome.jpg
 
yeah I know all about the dots. when that dot on the crankshaft lines up with the dot on the oil pump it's in stage one timing position. Besides the marks the flats on the back of the cams should be parrallel or in other words you can lay a straight edge across them. The special holding tool does just that. my engine does just that. and the same for second stage. Pretty sure it's timed right. the question is does the stage one timing mark represent TDC
 
I believe neither stage 1 or stage 2 marks are TDC. It's an interface engine so they have you rotate the crank to two different positions for each bank so you don't run the risk of valve contact when aligning the camshafts for the secondary chains.

You can either mark the gear positions and pull it apart and reset the chains to the colored links to see if anything moved. Or count the number of links between the colored links and compare that to the amount of links you have between the dots. The second option is what I would try first because you don't have to remove anything and that should hopefully be able to point out what is off.
 
Do you still have that engine in your garage you could verify that on? Be interesting to know where the dots are at in relation to TDC. If indeed the crank is good then the issue would have to be that the primary chain slipped to damage both sides.
 
ak diesel driver said:
Do you still have that engine in your garage you could verify that on? Be interesting to know where the dots are at in relation to TDC. If indeed the crank is good then the issue would have to be that the primary chain slipped to damage both sides.
Click to expand...
Consider this. Assume that the crank was installed and set at TDC, but both intake cams were set off (for whatever reason, misread timing marks, whatever) so that they were already advanced/retarded when the chain was installed so that the engine ran, but when the VVT was actuated it caused the valve timing to be off enough that piston to valve contact occured on all intake valves to cause the bending.
 
So my understanding of the phasers is that before they're actuated there in a , for lack of a better word stock or retarded position. Then when actuated they're advanced hydraulically via the PCM. The other thing to consider is that this happened all at once. If it was off initially it would have done this during break in when I flogged it pretty good
 
Unfortunately I already have that engine back together and running. Just need to finish up a few more test drives.

If you have the timing off initially it would set codes fairly fast when its running. The PCM knows what the timing should be at X% of VVT command. So if it commands X amount of timing advance and sees less or more it will set codes.

When I see these jump time and cause the engine not to run generally I dont find any timing codes because it happens to fast for it to set. But if the chain guide breaks and it still runs it will set timing codes. I will normally clear them out and restart it engine. If the code comes back then I start looking into timing issues. If it doesn't then alot of times low oil or an intermittent sticking VVt solenoid is the problem.

My guess is this happened suddenly and you had it correct when you put it together initially. Just need to track down what happened. Looks like Ohio and Alaska is a 4 hour time difference. I can call you later this evening and try to point you in the right direction of your still having trouble figuring it our.
 
So I called both cloyes and melling this morning they both agreed it sounded like it is still in time. Neither could answer anything about TDC. Still waiting on a call back from cloyes as the tech was going to talk to his boss about it.
 
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