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Vortec 8.1 intermittent engine squeak noise

Waffeey
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Waffeey Enthusiast

Waffeey

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Hey all, my 2002 Silverado 2500HD 8.1L w/ Allison transmission recently started making an intermittent but rhythmic squeaking/scratching noise that seems to be coming from engine internals. Video of engine noise https://drive.google.com/drive/folders/1ANVafHeQLibrg7velXbiScdqP4Fb3hlF

Noise is about the same through rpm range. Engine has 240k on it, no aftermarket modifications. Fearing lifter failure I went ahead and pulled the intake manifold to inspect lifters, did not see any loose retaining clips and felt all pushrods, none have excessive play. Attached pictures of lifters. Cam lobes that I could see looked fine. When I get off work I will spin the engine over, feel all pushrods for play as the bad one could be compressed and not showing play currently. Also will pull the valve covers and inspect springs/rockers. I know I jumped the gun by tearing down but has anyone else had experience with this noise? Sound seems to be coming from top end, not a deep noise like bottom end. I do have a one snapped off exhaust manifold bolt, rest are tight but doesn't sound like an exhaust leak to me. Appreciate any input thanks.

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Waffeey Enthusiast

Waffeey

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Found it, looks like a lifter failed and destroyed a lobe on the Camshaft. Also slightly bent pushrod and scoring on another cam lobe. From how deep the groove in the cam is I assume there has to be metal debris in the engine. Seems i should replace the long block or rebuild this engine entirely short block and all. Only other option I can think of is pulling and cleaning put the oil pan, replacing just lifters/pushrods/cam and praying no oil galleys get blocked.. Any advise appreciated!

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CamGTP Senior Enthusiast

CamGTP

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Posted

In all honestly, that is a pretty common failure to see on the camshaft.

 

Also pretty common that if you just look at the cam bearings, they will be worn. But it you don't look at them, then they won't ever be bad. It's the game we play when swapping LS camshafts lol.

 

If it was me I'd rolling the dice. Think about it a little, it took a long time for the lobe to get that bad, that's not a 1-2 miles worth of run time failure. It's been chewing that lobe up for a long long time. Slap a new camshaft in there, new lifters and keep running it.

 

But if you have time and don't mind the truck being down, then repair what you got and then some. Send it out to be cleaned up, install new camshaft bearings and new rod/main bearings. That's usually cheaper than a complete long block.

  • Like 2
newdude Senior Enthusiast

newdude

Posted
Posted (edited)

I think Cam's approach is pretty on with this.  New cam and lifters and run it, or pull it for cleaning, new bearings (cam, main and rods), cam and lifters.

 

The Gen 5 LT camshafts we've changed at work, only one so far needed camshaft bearings.  And the lobes on these looked worse than how yours does.  Far more pitting/delamination and nowhere near 240k miles.  More like 50-100k.  Cop Tahoe smoked a non AFM cylinder lobe at 78k.  

Edited by newdude
  • Like 1
Waffeey Enthusiast

Waffeey

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Okay gotcha, truck still had good oil pressure so i will try not to look at the cam bearings! 😆 I will be going that route and doing cam/lifters/pushrods and do a crankcase oil flush. I have heard bad stories about remanufactured lifters being lower quality, any brand would you suggest?

  • 2 weeks later...
Waffeey Enthusiast

Waffeey

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Posted (edited)

Left a rag in intake runner, got sucked in and probably bent valves and kissed the piston... Thats what I get for being an idiot.

 

 

 

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Edited by Waffeey
An idiot

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