Vortec knocks when cold

[frito-bandito]

Mine did that and it turns out I was running too thick oil. I put the recommended 5w30 in it and haven't heard a knock or tap since.

 

[ChrisAU]

My 92 does it, but not my 07.

 

[Tempted]

Mine did that and it turns out I was running too thick oil. I put the recommended 5w30 in it and haven't heard a knock or tap since.

That is common. Never run thick oil because you think a high mileage motor needs it. An engine needs oil volume much, much more than oil pressure. Thick oil might raise your pressure, but its only reducing the volume and pushing less through the system.

 

[BubbaZ71]

My 93 has never done it from the day it was new till now and the 88 i just got does not do it..Altho my dad has a 92 RCLB 2500 with a 350 and his does it occaisionally

 

[am92]

Mine does it, but just for 5-10 seconds right when i start driving and then stops. Only when its cold out and only on acceleration though, not at idle after I start it

 

[SAATR]

My Burb will do it for a few seconds when she's cold, a nice tap-tap-tap. Oil pressure is great and no metallic bits in the oil, so I roll on...

 

[JollyGreen]

I don't believe it'll hurt it if it's only doing it for a little bit. Mine started doing it a few months ago when I start it in the early a.m.

 

[Tempted]

I don't believe it'll hurt it if it's only doing it for a little bit. Mine started doing it a few months ago when I start it in the early a.m.

A little bit, no. But he is saying 3 minutes, that will probably require attention sooner than later. It very would could be a loud injector, though. Try using a bottle of Lucas upper cyl lube.

 

[TruckinAin4Sissies]

That is a long time to have a knock, 3 minutes. I'd be rebuilding/replacing it.

It'll be swapped (hopefully) soon.

 

[Swaggerwagon]

like most others in here, i have a 5-10 second knock at cold start up(only in the winter months)...then she's good to go...

and +1 to if it's knocking for 3 minutes, then you have a motor fixing to go down on you...better be finding a replacement or rebuild soon...