cold start knock? Is it normal

[LOH CHO]

I have a 97 5.7 vortec with 238km on it, on a cold start more towards this time of the year and throughout the winter I hear a knock for a couple minutes before the truck warms up. My thought is that its just piston slap? Is this normal? Im new to owning a vortec, and Im not too concerned about it but just thought id ask.

Cheers from the north

 

[1997chevydriver]

I have the same and so do a few other people. I made the mistake of replacing crank and bearings hoping to solve the problem but my efforts were worthless

 

[5spd Z71]

Mine does it just for a few seconds until the oil pump gets the oil up top. Im thinking mine is coming from the rocker area though.

Have you tried running an oil with a good zinc content or high film strength?

 

[bluex]

I gotz it to. I'm just running mine till it dies. like yours its only in the winter an the colder it gets the louder it is.

I just pretend the truck is telling me good morning an how much it missed me.

 

[Horns]

That's somewhat normal because the oil is so much colder. It takes a lot longer to get to the top end. A better winter oil might help.

 

[1997chevydriver]

Mine does it just for a few seconds until the oil pump gets the oil up top. Im thinking mine is coming from the rocker area though.

Have you tried running an oil with a good zinc content or high film strength?

yes....

I gotz it to. I'm just running mine till it dies. like yours its only in the winter an the colder it gets the louder it is.

I just pretend the truck is telling me good morning an how much it missed me.

That just might work

That's somewhat normal because the oil is so much colder. It takes a lot longer to get to the top end. A better winter oil might help.

mine does it during the summer now too just not as bad

 

[bluex]

That's somewhat normal because the oil is so much colder. It takes a lot longer to get to the top end. A better winter oil might help.

It didn't matter what I ran in mine last winter, nothing quieted it down until the outside temp average was above 60*.....

 

[97PROSHOZ71]

Mine does it when it is cold and it's not at operating temperature. Once it gets to Op. Temperature it quits.

 

[chevyman0191]

My old block did this for years and didnt have any problems.

 

[towman]

my 94 wich is not vortec,, gm had a tsb out years ago telling the dealers to put a fram filter on instead of a ac delco, as much as i thought it was crazy put a fram on two weeks ago and have not had a cold start knock since, guess the anti drain back valve on a fram tough guard is better than the delco