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The only thing that does that is the pistons hitting the valves.

I did that at high RPMs, about 7000, but it was only one valve.

It sounds to me like whoever put the cam in did not check for piston to valve clearance; the chains are loose at startup, until the oil pressure comes up, so that's probably when they hit.

This is the first time I've heard of this particular problem.

If the valve is moving sideways, the guide is cracked or worn badly.

I'd pull that motor, and go over everything carefully; you could have broken chain guides or something.

The heads have to be reworked at a minimum; the valves are probably bent, and at least one guide is bad.

Do a teardown, and post pix.

There will be marks in the carbon on top of the pistons, showing what happened.
 

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Discussion Starter #22
Thanks Grog, that was my initial thought as well. PTV contact or loss of oil pressure. There is no side to side play in the valve, it's in there very tight. Tight enough that it will not budge. It is possible that this was not a factory cam and it was installed incorrectly. Aside from giving everything a visual inspection, I put the motor in as it was from the original seller, so no clue if the cam was factory PI or not. I'm going to start tearing in to it this weekend, and will post up some pics after.
 

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I was looking at the cams listed in your sig; Comp XE268's.

Loss of oil pressure will either cause the rods to knock/seize, or the cams to seize; Cams break chains if they seize.

Valves only fail like that if they hit something.
 

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Discussion Starter #24
I was looking at the cams listed in your sig; Comp XE268's.

Loss of oil pressure will either cause the rods to knock/seize, or the cams to seize; Cams break chains if they seize.

Valves only fail like that if they hit something.
Ahh, got it. I need to update my signature. Those cams were in the original motor, but when it blew I essentially replaced it with what I thought was a stock '02 Mustang GT motor. Update: I got the top end off and I am close to having the front cover off as well. The timing chain going to the head with the stuck valves is extremely loose, I suspect what I will find when I get the cover off is either a failed tensioner or broken guides. Either way I will get some photos up of the results. Taking my time here, but hoping to have more info this weekend.
 

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Discussion Starter #25
Here is what I found when I finally got the timing cover off this weekend... Looks like the passenger side tensioner has failed. It also looked like the guides were toast on that side as well. Next step is to get the head off and over to a machine shop for new valves, guides and seals for the three that were damaged. Anyone have any ideas as to what could have caused this? Also, I was under the impression that the 02 and 0 GT's came with the plastic tensioners without the ratchet system, which leads me to believe that the previous owner may have replaced these in the past.

36903
36904
36905
 

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The 03 cars definitely had plastic.
36906
 

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Discussion Starter #27
Update: I got the passenger side head off this afternoon, and was a bit surprised to not see any PTV contact on the pistons. I ran the car for a while after the issue started so it's possible that all of the un-combusted fuel had washed off the marks. Anyways, after I got the head to the machine shop they determined that 3 of the intake valves and guides were bad (I am assuming this means bent, but I didn't ask the tech to elaborate) I should have the head back on Thursday and will start getting things put back together, hopefully before it starts getting colder.
 

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Discussion Starter #28
Alright, I have the head back on and torqued down. I made sure to put the head on with the pistons down to avoid PTV contact when putting them on. My next challenge is timing the pistons/cams since I have pulled the whole thing apart. From what I can gather I need to pull the cams off, and set the #1 piston to TDC, and from there the cams should go back on with the timing marks in the 12 o'clock position, and from there I line up all of the timing marks with the chain end links. My question is, how do I know if the engine is in the intake or exhaust stroke for TDC? Does it matter since the ECU is using the cam sprocket as a reference does it automatically know?
 

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You’re way overthinking it. Simply lay the chains flat and Mark the links at each end that are vertical, and just line the marked links up with the crank sprocket dot (at TDC) and the cam sprocket dots. Dot to dot, simple as that.

You can do this with the cams loose but I prefer to have the followers removed. Then just rotate the crank with the keyway facing straight left or right where all pistons aren’t at TDC and pop the followers back in with a screwdriver.
 

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Discussion Starter #30
You’re way overthinking it. Simply lay the chains flat and Mark the links at each end that are vertical, and just line the marked links up with the crank sprocket dot (at TDC) and the cam sprocket dots. Dot to dot, simple as that.

You can do this with the cams loose but I prefer to have the followers removed. Then just rotate the crank with the keyway facing straight left or right where all pistons aren’t at TDC and pop the followers back in with a screwdriver.
I'm sure I am. Just don't want to tear back in to this thing once I get it back together. Do all followers need to be removed or just the intake side?
 

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Discussion Starter #32
All. The purpose of removing the followers is the same as if you removed the whole cam - so you can position the chains and sprockets freely without valve spring pressure fighting you from moving the cam around, or staying in place.
Got it. Thanks for the help, I'm going to give it a shot this afternoon.
 

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Discussion Starter #33
Update: I got everything lined up this afternoon. Marked timing chain end links, with crank timing gear at 6 o'clock lined up the cam timing marks on both with the end links and timing mark on crank gear with other side. Released the tensioners. I start rotating the engine by hand to make sure nothing is binding, and I get to roughly half a rotation (timing mark at 12 o'clock, keyway at around 4-5) before things bind up. FYI, all spark plugs are out. I am pretty well stumped at this point. Any ideas what I could have done wrong here, or why things could be binding up?
 

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Take a pic with it together, get the chain marks in the pix. :)

This is a stock PI motor, correct?

You want to turn it over, by hand, at least 4 times with the spark plugs out, to make sure nothing is touching anywhere.
If you get the marks lined up, it should be fine, but I always do this for a new engine.
I do it with the front cover off, so I can see the tensioners drip oil, and makes sure oil is getting to the top of the engine..

If you feel any tightness, figure out why before you hit the starter.

EDIT: I walked away to deal with cat issues, and just saw your post.

Pop the chains back off, yank the followers, line it all up again, and post pix of the cam and crank, with the chains at the marks.
 

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Discussion Starter #35
Stock PI motor. Passenger side head was replaced with a remanufactured unit after it was trashed in earlier part of this post, aside from that everything is 100% stock. I'll take a few pics of it tomorrow and post up with the timing marks shown. It was dark when I got it all back together this afternoon. Timing mark on crank is at 6 and both cam gears are close to 12 respectively with the end links lined up on the timing marks. There is only one timing mark on the front of the crank gear correct, and both cam chains line up to the same mark?
 

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Discussion Starter #37
Check out page 9 of this pdf:


If you can't see the copper links, fold the chain in half, and mark the two end links.

If it won't turn over by hand, that may not be a stock cam, and may need to be degreed.
Thanks Grog, that's one of the articles I used to time the motor initially. Your last comment has me wondering. From what I have been reading the cams are L/R specific correct? I am wondering if the machine shop put a Left cam on this head. I could only find one set of markings which look to be 87431D131 on the cam.
 

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In the middle section of the cam will be a part number stamped into the cam.
The base part number on he stock cam for the drivers side is 1L2Z-6250-DA
The pass side should be 1L2Z-6250-AA

This should be right in the middle.

The cam gear is labelled also.
It won't start with the cam gears swapped, there's a boss for the cam trigger sensor.

Note that the cams have been known to have the insert in the end that holds the gear move, so that could also be it.
Set it up and degree it if the cams are on the right sides.
 

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Discussion Starter #39
Update: So what I thought was a PTV issue may be something else. I removed all of the rockers as suggested for both heads, and when I attempt to rotate the crank I am still getting hung up with the timing mark right at 12 o'clock on the crank gear, which from what I gather is TDC. It does not sound like metal to metal contact, the rotation just stops. Everything turns super easy by hand up to that point. Any ideas here? Is it possible this is binding on the starter?
 

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Are the spark plugs in?

Compression will stop it as it comes up, but it will bleed off in a few seconds.

With the followers out, it should rotate freely; there's nothing for it to hit.

Did you have both heads off? If not, you need to pull the other one.

Somethings not right; don't try to start it until you figure it out.
 
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