Anybody have a clue as to whether I'm looking at chain damage here? I have an 08 and I know it's notorious for chain stretch. Basically I was drying down the road and had the car in neutral (coast to stop) but noticed a stiff steering wheel, and naturally the engine was off. I tried to crank it stupidly but it wouldn't have it. It was making full revolutions, and sounded like it wanted to start but it didn't. Luckily there was an autozone not 200 feet away so I picked up a spark plug remover. The very last spark plug took a serious beating, the electrode was bent and all. The others were all fine. I also pulled the valve cover off, I'm not sure if this is right, but the timing marks look way off to me. Can anyone verify?

 

Looks like a timing chain.

Do you have a photo of the spark plug damage?

 

Sure do.


I also did a compression test and cylinders 1 & 4 barely moved the needle. Cylinders 2 & 3 peaked at around 90. Is there any way to check for bent valves/piston damage?

 

Oooh that for sure looks like contact being bent to the side like that.

The fact that you have no compression in the cylinders is not a good sign.

Pick up a cheap $25 USB borescope on amazon and take a look inside your cylinders. I bought one and they work great!

Here is the one I picked up:
And some images from it I took:

 

Sounds great, I had a feeling something foreign may have entered. I just don't know what it could be. I even checked the throttle plate to make sure both screws are there lol. I'll pick up the horoscope to see what I can find

 

keep in mind the little orange links wont line up with the gear marks after its been run or turned over by hand (well, there is a small chance they will be at just the right spot) since most everyone uses hunting style chains (the same chain link doesn't come back to the same gear tooth every time. promotes more even wear i believe). What matters would be that the gear marks line up in relation to the block, head, and each other and each orange link is the same number of teeth off in the same direction. That would tell you if it skipped.

If the chain was stretched you should have gotten a trouble code alerting you to the condition long before it was enough to cause a stall/no start or interference.
That video talks about the timing system of the 4b11t. If you watch it, just note that the pictures to tell if there is stretch are a top view looking straight down into the timing cover. It took me a little bit to see wtf i was looking at.

As far as checking valves and pistons a bore scope can show you an impact mark where piston and valve met on the top of the piston but unless it comes with a mirror end attachment you wont see the valve. On top of that valves can be bent too little to see and still not seal. The better way in my opinion is a leak down test. Just involves pressurizing the suspect cylinders on a compression stroke with air. Can buy a special tool or the more DIY version just uses a compression tester in the spark plug hole with an air compressor where the gauge would normally be. Lots of air coming from the tailpipe is bent/burnt exhaust valves. From crankcase is piston/rings. From intake is intake valves. (don't let the PCV fool you if the crankcase uses the PCV to dump the air into the intake.) Small bit of air leakage is normal. Anything that you can feel with your hand is too much.

*Safety note* If the piston is mid way up, adding pressurized air can whip it back down rather violently.

 

This is great information guys thank you so much! I have a horoscope on the way (Thanks razorlab) which has a mirror attachment included. I'm hoping that gives some kind of insight as to whats going on.

Also, Spazm thanks for your insight, my simple mindedness didn't even consider that. I assumed the colored links would always return to the marks on the cams I'll bring the #1 piston to TDC tomorrow and check the markings on the cams in relation to the block so see how they look.

 

I agree on the leak down test suggestion.

The mirror on that kit (and most) is not possible to get through the spark plug holes so don't count on getting any images of the top of the cylinder. However it will give you good images of what state your pistons are in.

 

Horoscope says: You'll be pulling a cylinder head soon

I'm sorry, but whatever danced with your spark plug is going to necessitate pulling the head. Hopefully the damage is confined to that one cylinder. Good luck!

Sub'd for carnage pics....

 

I'll be doing a leak down tomorrow hopefully, and the borescope will be delivered tomorrow so I'll post some pics then. What a lovely day fellas. Whatever got in there will be pointing a middle finger at the camera.

 

Well, I finally got pics of the inside. It looks like Piston #4 had a catastrophic failure. Anybody have any clue what could have caused this? I don't even know the best course of action to take at this point.

 

Bad news: new engine build. Good news: more power

 

sorry just saw your signature and you are CBRD tuned.

 

Thats usually an idication of detonation. CBRD is a good tuner, so I'm going to go with you got bad fuel, and or the cam timing being off caused an increase in cylinder pressure that wasn't accounted for in the tune (timing likely jumped after tune), or piston to valve contact could have broke the piston (this isn't as likely.)

 

Either way this will be interesting. I'm talking with Chad@CBRD now to see what the best course of action is. I'll keep you guys updated.