2007 Tahoe Timing Chain Replacement

[Rocket Man]

I now have the balancer and timing cover off I am going to replace the oil pump, tensioner, both spockets and chain. Mine is 4WD, so I am planning on dropping the pan enough to set on the cross member to see if I can get to the pick-up tube o-ring without dropping completely - well see.

This all started with trying to replace the !@#$ cam sensor, that little SOB would not come out for nothing so that is why I am at the stage I am. After inspecting the timing cover, I notice that in my efforts to remove I scored the side of the hole the cam sensor sits in, I am now wondering if I need to but a new cover?

Also, noticed there are pieces of plastic lodged in behind the crankshaft gear and a small piece was loose and laying on an edge on the block. I assume it is plastic from the tensioner (pix attached)View attachment 374201View attachment 374200

Just pull the bolts that hold the front diff to the frame and let it droop. At the most you might need to pry down a bit as you remove the pan. It’s not worth trying to fight this. It will make it way easier to replace the pan gasket and dab the silicone on the 4 spots where it needs it. I would pop rivet the new pan gasket back on the pan too, it keeps it from moving when you reinstall. Don’t want an oil leak from the pan when you’re done.

 

[Plimbob]

I wonder if I should replace the timing cover due to scoring the hole that the cam senor sits in when I was trying to remove?

 

[iamdub]

Just pull the bolts that hold the front diff to the frame and let it droop. At the most you might need to pry down a bit as you remove the pan. It’s not worth trying to fight this. It will make it way easier to replace the pan gasket and dab the silicone on the 4 spots where it needs it. I would pop rivet the new pan gasket back on the pan too, it keeps it from moving when you reinstall. Don’t want an oil leak from the pan when you’re done.

Or, if you don't have the means to rivet, you can tie the gasket in place in four corners with thread or fishing line. Once you get some bolts in and started, cut the strings, pull 'em out and proceed as normal.

 

[iamdub]

I wonder if I should replace the timing cover due to scoring the hole that the cam senor sits in when I was trying to remove?View attachment 374220

Can't tell from the pic- does the damage extend to where the sensor's seal contacts?

 

[Rocket Man]

I wonder if I should replace the timing cover due to scoring the hole that the cam senor sits in when I was trying to remove?View attachment 374220

If you think there’s any chance at all that it will cause a leak, in other words if it’s near the o-ring I definitely would. It’s only about $45 and you sure don’t want to have to pull everything apart a second time.

 

[Geotrash]

I now have the balancer and timing cover off I am going to replace the oil pump, tensioner, both spockets and chain. Mine is 4WD, so I am planning on dropping the pan enough to set on the cross member to see if I can get to the pick-up tube o-ring without dropping completely - well see.

This all started with trying to replace the !@#$ cam sensor, that little SOB would not come out for nothing so that is why I am at the stage I am. After inspecting the timing cover, I notice that in my efforts to remove I scored the side of the hole the cam sensor sits in, I am now wondering if I need to but a new cover?

Also, noticed there are pieces of plastic lodged in behind the crankshaft gear and a small piece was loose and laying on an edge on the block. I assume it is plastic from the tensioner (pix attached)View attachment 374201View attachment 374200

Yup, that tensioner is toast. Not a fan of that design at all.

And as others have said, just drop the front diff down on the pax side. Easy. You won't have enough clearance unless you do. And I agree with replacing the timing cover. Cheap insurance.

 

[Plimbob]

I'll go ahead and order a new timing cover, I am thinking I'll order a new cam senor sub harness as well. I inspected it and looks OK, however I didn't test it but for $20 and the fact its been on there for 306K seems like another case of cheap insurance.

A couple more questions if you guys have time;

1. As far as dropping the differential, do you detach the shafts as well?
2. Is there a way to keep the engine from rotating once new gears/chain are on and lined up if you don't have the flywheel tool?

 

[Rocket Man]

I'll go ahead and order a new timing cover, I am thinking I'll order a new cam senor sub harness as well. I inspected it and looks OK, however I didn't test it but for $20 and the fact its been on there for 306K seems like another case of cheap insurance.

A couple more questions if you guys have time;

1. As far as dropping the differential, do you detach the shafts as well?
2. Is there a way to keep the engine from rotating once new gears/chain are on and lined up if you don't have the flywheel tool?

No need to detach the axles, just remove the 4 bolts holding the diff to the frame and it should drop enough for the pan to come out. On my 02, I had to pry it down another inch or so and I think I stuck a 2x somewhere in there to keep it down.

You will need to remove the starter and use a flywheel tool that replaces it and locks the flex plate so the engine can’t turn over. You shouldn’t need to remove the wires, just slide the starter forward out of the way so you can install the tool. I used one like this, not sure if any auto parts stores carry them. Just search for LS flywheel tool.

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[Geotrash]

I'll go ahead and order a new timing cover, I am thinking I'll order a new cam senor sub harness as well. I inspected it and looks OK, however I didn't test it but for $20 and the fact its been on there for 306K seems like another case of cheap insurance.

A couple more questions if you guys have time;

1. As far as dropping the differential, do you detach the shafts as well?
2. Is there a way to keep the engine from rotating once new gears/chain are on and lined up if you don't have the flywheel tool?

I detached the half shaft from the flange (only six 13mm bolts) and it allowed it to hang down low enough that I didn't need to use a pry bar to get the pan off. Personal preference but both methods are valid.

On the crank bolt, I'm assuming you mean holding the crankshaft still while you install the harmonic balancer bolt? If so, then yes if you're planning to torque it precisely to spec because the factory bolt is a TTY stretch bolt requiring an angle gauge as well to torque properly. I bought an ARP harmonic balancer bolt which is not a stretch bolt, and is torqued without the need for an angle gauge. It's also reusable, which tuned out to be a money saver for me. That said, I just used my impact wrench and a 12-point impact socket to torque it until it was 'good-and-tight'. That way I didn't have to mess with the starter. Your choice about whether you want to go this route but I haven't had any problems. Just to be safe, I gave it another shot with my impact wrench after about a month of driving, and it was still good and tight.

 

[Plimbob]

Another question, the timing mark on the cam sprocket is sitting at about 8:00 o' clock. Before I remove it and the crank sprocket, should I line those up at TDC?

Also, if so, I assume I need to rotate the engine clockwise to get the timing marks to line up. Because of the distance of rotation I'll need to remove the plugs so it rotates easier?

Thanks,
Tim