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Engine knock in chevy 350


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Darth-War
New User

Dec 28, 2007, 9:30 PM

Post #1 of 4 (3600 views)
post icon Engine knock in chevy 350 Sign In

i have a knock in my engine, but only at certain times. I can drive the truck for hours and the engine is nice and quiet. When i turn it off and then start it back up like 5min later it will start to knock. The knock lasts about 5min and then goes away. This is a 1990 full size blazer 350 TBI 4x4. Do i need to change the cam and lifters? Do i need to change valve springs? Help.....


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Dec 29, 2007, 12:20 AM

Post #2 of 4 (3598 views)
Re: Engine knock in chevy 350 Sign In

Could be several things. Is this engine fairly free of sludge? Temp senstive noise as described could be low oil pressure or pump ability, or piston slap which does go away when warmed up. Get an oil pressure reading done right at the engine not just the gauge it has,

T



Double J
Veteran / Moderator
Double J profile image

Jan 2, 2008, 4:26 PM

Post #3 of 4 (3578 views)
Re: Engine knock in chevy 350 Sign In

HEY TOM

this reminded me of the days when we had several tow trucks running 'round the clock....
went thru engines/clutches like you wouldn't believe...anyway
we would get used engines most of the time....cuz drivers beat hell out of the trucks...
most times engines came with 2 bbl carbs...i would change manifold and carb....
one time in particular,took off intake ,engine was clean as a whistle...started it up,knocked liked hell...
sent it back ,got another one,same thing,clean,knocked like hell......
sent back
third one was sludged up like the oil was never changed....didn't want to accept it but had to get the truck
rollin',they didn't have another at the time...it was winter,busy time no doubt...let junk yard know...told them to get me another one ...put it in,started it up,guess what? quiet as a church mouse.....ran that sucka for a good while..
go figure......against everything we preach....oh well.


way2old
Veteran / Moderator
way2old profile image

Jan 2, 2008, 4:47 PM

Post #4 of 4 (3575 views)
Re: Engine knock in chevy 350 Sign In

or piston slap which does go away when warmed up.

T


I gotta agree with this. Have run into a lot of them.



Being way2old is why I need help from younger minds






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