knock at start up

[QUIP'6']

what would cause knock at start up? every other time i start my car it registers knock like jumping to 25 then slowly powers as rpm lowers. is this a defective sensor?

 

[Squid4life]

Do you actually HEAR knock, or is it just the Caspers knock gauge registering knock from the sensor? I get it on startup on my audible knock alert, but not from motor knock, instead from the starter & flex plate meshing.

 

[wickedtt]

What oil filter are you using, wha weight oil are you using. How long in between start ups? Background on the motor how many miles.

 

[QUIP'6']

its showing up on the scanmaster just turning key and starting. new motor maybe 200 miles. 20/50 racing oil and pl30005 biggie filter

 

[vacuum 6]

My knock gauge always registers knock at startup.

Forget about the scan tool, does the engine knock at startup?

 

[JimP]

your probably seeing the starter engage the fly wheel, I see that too on my Casper gauge as well as scan-master.

Now if your hearing vale train noise or bottom end knock then there is an issue. I'm going to go out on a limb though and assume it's the first, starter teeth engaging the flywheel.

 

[GNVenom]

About knock...

Startup knock is not the kind that can really cause damage to the engine. It's the high-load knock - detonation - that's damaging. I wouldn't worry too much about that knock.

Basically, when the engine knocks, the fuel burns before it's supposed to, pushing the piston down the bore when it wants to move up the bore - causing a great deal of stress on the piston, connecting rod, crank, and bearings.