Lions3

When I start my car, I sometimes get a small knock. It'll sound like..

Crank crank knock VROOOOOOOM idle idle idle

The engine runs like butter though. No stumble, no misses right through the power band and nothing else to complain about. I only get this knock on startup, and even then it's only sometimes. Any ideas?

PS no codes.

usem

How many miles are on your engine?
What type of oil and filter are you using?

TTT for you.
-Mike

moparman

I've heard Fram oil filters can cause this.

MisterGuru

From what? A bypass valve?

Sounds like it may be starter/flywheel related... if the pop or knock is just when cranking, not running.

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Ws6Envy

same problem.....any more ideas????

Donny O

same thing with mine. I always assumed it was jsut the force of it firing and starting up with no initial oil preasure adding to it.

moparman

It has been noted on this board that Fram filters can cause a knock at start up. If you have a Fram oil filter, try changing to better filter. Just do a search for oil filters and you'll find out more than you want to know.

Ws6Envy

i use ac filters.....i am really concerned with this knock sound......should i be?

3.1firebird

I searched in the archives and came across this old thread, but my 94LT1 does the same with 135k and an AC oil filter. Small knock only on startup, I can hear it sometimes when I shut it off.

Let's hear some more idea's....

Lions3

Woah. Bring this one back from the dead

I since traded that car for a 94 TA, and it does the same thing. No problems though.

3.1firebird

yea this thread was pretty much a buried and decaying corse

I guess I will quit worrying about it. If it breaks one day it breaks.

chasmanz28

i get the knock to but only in the cold months and how can the oil filter cause that knock even though i use gm filters

chasmanz28

any ideas

Donny O

have you ever heard a car right at first startup after an oil change?? usualy their is no oil in the filter and it takes a few seconds to fill it and build preasure and the engine will knock for a few seconds.....this is what people are talking about if the filter not holding oil/preasure.....after the oil goes into the filter it goesinto passages to get around in the engine....after you shut the engine off if the oil all drains back into the engine then it will also take a second to build this back up.....that make sence?

Lions3

Makes sense, but the engine build pressure while it's cranking. And any shop that does an oil change should be switched on enough to fill the filter up as well.

To me, it sounds like it knocks when it first makes ignition. So it isn't when the flywheel is first engage by the starter, and it isn't once it has hit idle.

It only makes a knocking sound when it's burning up all the accumulated fuel.

Doesn't seem to be hurting anything, or get worse, but it's sorta annoying.