Life Expectancy of Timing Chain

Koinz · October 22, 2006

Hi,

Just bought an 2001 GMC Sierra Extended Cab 5.3L Z71 4x4 with 110,000 miles. I don't know if the timing chain has ever been replaced on it. Truck runs strong and smooth.

Should I have it replaced to be safe or let it go for awhile. Not sure how long they generally last on these "newer" engines.

I used have an old K5 Blazer with a 350 many years ago. The thing was a tank, but since then I have been trying V6 Cars and usually get rid of them before they hit a 100,000 miles.

First time I ever bought anything over 100,000, but the truck runs great and well maintained.

Your advice is appreciated. Thanks in advance.

dewfpo · October 22, 2006

No worries about the timing chain. They'll last longer than the rest of the truck.

DEWFPO

99Silver6.0 · October 22, 2006

You dont have much to worry about in the chain. If later down the road you get alot of crank relearn codes, its gonna be time to put in a new chain. When I swapped the cam in my old 5.3 that had about 60K miles on it, the chain had a big amount of slack in it. The LS2 timing chain is a great, inexpensive alternative to a pricey double roller chain. At $30 bucks the LS2 chain is a good one thats alot beefier than the stocker!!

Koinz · October 22, 2006

That's great. Thanks for your responses. I'll search the threads on how to determine the codes now. I'm not getting any, but when I do it'll be nice know how to troubleshoot them.

I guess I should pick up a decent service manual for the truck. Any recommendations would be helpful.

Thanks.

95Sierra2500 · October 23, 2006

I don't know if it's the case on your truck, but beware that GM had a tendency to do stupid things years ago...like use an aluminum cam gear in the timing systems...that would lose its nylon coating and then strip, causing carnage throughout the engine.

Koinz · October 23, 2006

Now that's what I was eluding to. I have never seen a Timing Chain Break. It's the gears I'm worried about as well as the chain jumping a tooth on worn Gears.

I'm really glad you brought that up.

Perhaps then, I should restate my question.

I have always replaced timing chains and Gear's as a set...and I usually replace the old nylon coated gears with metal gears. (Noisier, but probably last longer).

Is the Stock Cam gear Nylon coated?

How many miles before a Chain is Stretched enough to damage the cam gear and jump a tooth?

I haven't replaced a V8 timing chain in about 20 years and wondering if the parts and technology have gotten better.

Thanks again for bringing up the Cam Gear nylon coated thing.

Wingnut · October 23, 2006

I don't think I've read a single thread on here with a worn/busted timing chain on the 5.3, or any of the Vortec V8's for that matter.

Koinz · October 23, 2006

It really sounds like things have gotten better over the years.

I have also tried searching and didn't find any Cam Gear/Chain issues anywhere.

I didn't want to sound like there were any issues. I am only going from past experience. I used to replace Gears and Chains around 100,000 miles and my truck is already at 110,000.

Thanks Guys.

TEE · October 23, 2006

Yep...Had a 70' Pontiac Tempest T37 that had that nylon gear and the only way you could get that 350 to run right was time it by ear only.

But man I'd give my lefty now to have it...stupid and young and no idea of what I had

95Sierra2500 · October 23, 2006

I have never seen a Timing Chain Break.

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I have. It's not a pretty sight. Again with the carnage inside the engine thing.

99Silver6.0 · October 23, 2006

I don't think I've read a single thread on here with a worn/busted timing chain on the 5.3, or any of the Vortec V8's for that matter.

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Only time you really see a chain break is in an f-body with a manual. Guys skip shifts, slam it into a lower gear rather than higher where they wanted to go. Thats when they break em, bend push rods.

95Sierra2500 · October 24, 2006

I don't think I've read a single thread on here with a worn/busted timing chain on the 5.3, or any of the Vortec V8's for that matter.

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Only time you really see a chain break is in an f-body with a manual. Guys skip shifts, slam it into a lower gear rather than higher where they wanted to go. Thats when they break em, bend push rods.

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It can happen on any engine from simple fatigue, or from a broken gear. I've seen 4-bangers break chains when they reach 150k miles.

99Silver6.0 · October 25, 2006

I don't think I've read a single thread on here with a worn/busted timing chain on the 5.3, or any of the Vortec V8's for that matter.

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Only time you really see a chain break is in an f-body with a manual. Guys skip shifts, slam it into a lower gear rather than higher where they wanted to go. Thats when they break em, bend push rods.

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It can happen on any engine from simple fatigue, or from a broken gear. I've seen 4-bangers break chains when they reach 150k miles.

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Understandable. Ive been in alot of LS motors. Seen guys pushing 700-800HP on stock chains with no problems. Seen guys running stock break the chain. Ive even seen a JWIS torrington chain break on simple heads/cam car. It just happens and you cant determine when. But when it does, it gets ugly in there.