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5.7L Vortec, Is it an Interference engine?

GM Guy

GM Guy

Manual Trans. 2WD Enthusiast
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NW Kansas and SC Idaho
I was wondering if the 5.7L Vortec (in this case, the 1998 HD one in old man's truck) is an interference engine.

(if timing chain goes, it f***s up the valvetrain) do not fully trust the timing chain.

any input appreciated, thanks!
 
Yah pretty much, if he timeing chain goes the cam will stop bumpin the valves open and closed so the crank will still be spinnin and ram the pistons into the valves, but don't worry it won't run very long once the tieming chain snaps it will proceed to self destruct. How many miles on the old girl. GM's timeing chains are pretty healthy units to begin with.
 
Is there something happening that makes you think the chain is going? I very rarely hear of a timing chain being the demise of a 350.
 
I have over 200k on my 98, and it is still fine.

EDIT: Scratch that, HAD 200k on the Tahoe, and the new owner will find out how well it holds up, LOL
 
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trouttrooper said:
Is there something happening that makes you think the chain is going? I very rarely hear of a timing chain being the demise of a 350.
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x2 on that. Unless you're running on water instead of 5w-30, I think it's very VERY rare for a timing chain to go.
 
No, other than the GM hatred by my old man :eek::nono: keeps telling me the timing chain will go. His international pickups have timing gears, so he is spoiled. (if you call diesel engine-like redline and shitty fuel economy spoiled, oh, and the non-galvanized, currently rusted out bodies):rolleyes5: (for a gleaner combine person, i would think he would like galvanized steel!)

don't understand either, he has a good friend that ran 350s in late 80s early 90s 1ton service trucks in CA (so basically a good test of a vehicle) and he says that they are trouble free, and they replaced the chains for good measure at about 250K.

we are also running 10w30. old man thinks we need to run 10w40(has actually done it a few times too, i got him off that kick), but i thought that GM engines didn't care for those wide viscosities, is this true?
 
I know a guy that runs Rotella in all his plow truck that are 5.7 vortec, he says they work well with this oil, I don't know
 
5W30 or 10W30 is the reccomended oil for a 350. The factory oil passages won't flow enough oil when cold at stock oil pressure if you run thicker than a 10W30. Pressure isn't as important as flow is. As for the timing chain, GM reccomends them be replaced at 150K miles. I know of a couple with 250K on the clock still going. The chains are LOOSE in them, but they are still going.
 
Like said above they are not known to be a problem, doesnt hurt to replace them for better performance though. Over the years the chain will stretch and the timing will be off. Being a Vortec engine the PCM can compensate i beleive up to 29deg to keep in time.
 
THEFERMANATOR said:
5W30 or 10W30 is the reccomended oil for a 350. The factory oil passages won't flow enough oil when cold at stock oil pressure if you run thicker than a 10W30. Pressure isn't as important as flow is. As for the timing chain, GM reccomends them be replaced at 150K miles. I know of a couple with 250K on the clock still going. The chains are LOOSE in them, but they are still going.
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I've never seen any GM literature that says to change the timing chain at 150K. I have driven GM cars and trucks (both gas & diesel) all my life and NEVER failed a timing chain. The only time I ever replaced a timing chain and gears in a 350 Chevy was when I installed an aftermarket cam and it really didn't need it then, but since I had already bought them I replaced them anyways.

If it makes you feel better, go ahead and change them. The chain and gears are not that hard to replace and not very expensive.
 
THEFERMANATOR said:
5W30 or 10W30 is the reccomended oil for a 350. The factory oil passages won't flow enough oil when cold at stock oil pressure if you run thicker than a 10W30. Pressure isn't as important as flow is. As for the timing chain, GM reccomends them be replaced at 150K miles. I know of a couple with 250K on the clock still going. The chains are LOOSE in them, but they are still going.
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Me: 1
old man: 0
):h
 
Had more problems with a flat cam on a couple of 454's,than anything. I do think that my 99 350 is a gutless pig in my suburban. But that is more of a weight issue and GM's crappy intake.
 
WilliamBos said:
:iagree: you can have a high pressure, or high volume pump, if you do not have flow, it is useless.

Wasn't the Achilles heal of the 5.7 Vortec intake gaskets??
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do not know the circumstances, but the crappy local Vo-tech blew it when they were changing the blinker switch. explain how that happens!:D:confused: so the gasket is changed, but IDK the quality of it.
 
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