2007 Yukon Timing Chain Tensioner Broke

[bowtiegurl]

2007 GMC Yukon SLT 5.3 liter LMG (8th digit 0). I was on the highway engine died like key had been turned off. Coasted to the side of the highway tried to restart but it just cranked with no start, sounded like it was fast free spinning with no compression. Had it towed home assuming the timing chain had broke. Mechanic brother-in-law took off timing chain cover and the timing chain tensioner had broke causing the timing to jump off time. Replaced with a Cloyes timing chain kit and also replaced camshaft position sensor. Both bought from O'REILLY'S. Once put back together it did not start, doing the same thing as it did before the parts were replaced. Cranks with free spinning sound. He never checked the compression with a compression gauge, did not pull a valve cover to see what was going on. Before tearing into it the only thing he did was remove the oil filler kneck and could see the cam moving. Now he wants to say the cam is broke. He didn't do any test to determine this so I am totally at a lost what's wrong with my vehicle. Any advice would help. I love my Yukon, it's in too perfect of condition to just trash. I need advice on where to go from here. Please and thank you.

 

[Doubeleive]

2007 GMC Yukon SLT 5.3 liter LMG (8th digit 0). I was on the highway engine died like key had been turned off. Coasted to the side of the highway tried to restart but it just cranked with no start, sounded like it was fast free spinning with no compression. Had it towed home assuming the timing chain had broke. Mechanic brother-in-law took off timing chain cover and the timing chain tensioner had broke causing the timing to jump off time. Replaced with a Cloyes timing chain kit and also replaced camshaft position sensor. Both bought from O'REILLY'S. Once put back together it did not start, doing the same thing as it did before the parts were replaced. Cranks with free spinning sound. He never checked the compression with a compression gauge, did not pull a valve cover to see what was going on. Before tearing into it the only thing he did was remove the oil filler kneck and could see the cam moving. Now he wants to say the cam is broke. He didn't do any test to determine this so I am totally at a lost what's wrong with my vehicle. Any advice would help. I love my Yukon, it's in too perfect of condition to just trash. I need advice on where to go from here. Please and thank you.

the work needs to be double checked, pull the cover off and make sure the timing marks are alinged properly, that should of course had been done when the kit was installed.
maybe it got rotated 180d?

 

[Marky Dissod]

Really hope this has nothing to do with 'CASE' - Crank Angle Sensor Error relearning?

 

[strutaeng]

I could be that the timing chain tensioner broke was the "effect" of something else, like a more serious thing such as a dropped valve.

The fact that it seems to spin freely is very concerning. I would do a compression test before proceeding further. Remove the intake manifold and exhaust manifolds and try to look at the valves.

 

[bowtiegurl]

the work needs to be double checked, pull the cover off and make sure the timing marks are alinged properly, that should of course had been done when the kit was installed.
maybe it got rotated 180d?

The cover was pulled yesterday and the timing marks were right on at 6 and 12.

 

[bowtiegurl]

Really hope this has nothing to do with 'CASE' - Crank Angle Sensor Error relearning?

Can you explain what that means please?

 

[bowtiegurl]

I could be that the timing chain tensioner broke was the "effect" of something else, like a more serious thing such as a dropped valve.

The fact that it seems to spin freely is very concerning. I would do a compression test before proceeding further. Remove the intake manifold and exhaust manifolds and try to look at the valves.

Is it not normal for the tensioner to break at 267,000 miles? This is all new to me so bare with me. The valve cover gasket was removed this morning and the rockers and valve springs move when trying to start the engine.

 

[Doubeleive]

Is it not normal for the tensioner to break at 267,000 miles? This is all new to me so bare with me. The valve cover gasket was removed this morning and the rockers and valve springs move when trying to start the engine.

timing chain issue's on these engines are pretty rare, not unheard of it's just not a common thing like the on the older 350's etc
as noted it is probably advisable to proceed with a compression test and verifiy you have fuel+air+spark and that something else did not happen during the repairs
such as a loose or disconnected harness, blown fuse i.e. megafuse, verify fuel pressure, etc..
in other words double check EVERYTHING

 

[strutaeng]

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.

 

[bowtiegurl]

timing chain issue's on these engines are pretty rare, not unheard of it's just not a common thing like the on the older 350's etc
as noted it is probably advisable to proceed with a compression test and verifiy you have fuel+air+spark and that something else did not happen during the repairs
such as a loose or disconnected harness, blown fuse i.e. megafuse, verify fuel pressure, etc..
in other words double check EVERYTHING

Thank you very much for your recommendations. Will get busy on it this evening.

 

[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...