2007 Yukon Timing Chain Tensioner Broke

[bowtiegurl]

Yeah, not normal for timing chain to break (or tensioner). If timing chain breaks, you usually got bigger problems.

Also, these engines are technically interference engines so a broken timing chain usually causes catastrophic issues such as bent valves due to to piston contact.

Researching whether the 5.3 liter LMG is an interference engine or not was confusing. Some say no some said yes. Thank you for clarifying this.

 

[Hobert]

Might be a weird coincidence but same symptoms for me on a 2001 Yukon XL. Driving on highway at 70 looked down and seemed as if the car was just turned off. Turned out the fuel pump went out. Check for fuel just to rule it out before going further.

 

[donjetman]

If valve(s) got bent a compression test will tell the tale.

 

[bowtiegurl]

Might be a weird coincidence but same symptoms for me on a 2001 Yukon XL. Driving on highway at 70 looked down and seemed as if the car was just turned off. Turned out the fuel pump went out. Check for fuel just to rule it out before going further.

It had a new fuel pump put in a couple of months ago. Did yours sound like it had no compression when trying to start it. Engine sounds like it's free spinning?

 

[j91z28d1]

compression test first.

if you have compression go from there... fuel, spark and did he line the cam and crank gear up right.

 

[Hobert]

It had a new fuel pump put in a couple of months ago. Did yours sound like it had no compression when trying to start it. Engine sounds like it's free spinning?

Cranked like normal

 

[R467X]

Pull your oil filter out and cut it open before you do anything else. Like others suggested, you may have blown something else. Do you have AFM? Could be a failed lifter turned major engine damage.

Did you have any weird noises leading up to? Major ticking, knocking?

I'd definitely do the oil filter first. Also consider pulling the oil pan out to check for debris there. I second the compression test. Also see if your engine turns over without issues when you turn the harmonic balancer bolt, it's a 24mm if I recall correctly (only turn clockwise)

You might find yourself needing to replace/rebuild your engine if you find any debris. I wouldn't risk any "band aids" if there's debris or metal shavings.

 

[Goldwing2000]

Yeah, not normal for timing chain to break (or tensioner). If timing chain breaks, you usually got bigger problems.

Also, these engines are technically interference engines so a broken timing chain usually causes catastrophic issues such as bent valves due to to piston contact.

This is the answer. Your pistons smacked some valves and now you have no compression. And since it happened at highway speed and the chain only jumped but didn't break completely, there's a good chance that valves and/or pushrods in all eight cylinders are bent. You're going to be pulling heads...