Engine knock on cold start?

[dace voit]

My '01 has a loud knock on start up when cold. It fades away after a few seconds and doesn't do it when the motor is warm, or in the summer on cold start. I'm looking for some suggestions as to what might be going on to cause this.

So, I posted this question a while back but realized that without sound, there's no way to hear what is actually going on. <duh>

So here are a couple of vids of a cold start up. The first is cold start and the second is of the engine revving just after cold start after the knock has going away.

Any input is greatly appreciated!

<iframe src="//player.vimeo.com/video/110834082" width="500" height="281" frameborder="0" webkitallowfullscreen mozallowfullscreen allowfullscreen></iframe> <p><a href="http://vimeo.com/110834082">IMG 1848</a> from <a href="http://vimeo.com/user34021345">Dace Voit</a> on <a href="https://vimeo.com">Vimeo</a>.</p>

<iframe src="//player.vimeo.com/video/110834083" width="500" height="281" frameborder="0" webkitallowfullscreen mozallowfullscreen allowfullscreen></iframe> <p><a href="http://vimeo.com/110834083">IMG 1849</a> from <a href="http://vimeo.com/user34021345">Dace Voit</a> on <a href="https://vimeo.com">Vimeo</a>.</p>

 

[JayRolla]

Lots of cars do this, especially when cold and after sitting. Not much oil up there for a few seconds. It can be called piston slap or other things. Mine has done it since ive owned it mainly when under 30* and or if oil is low. Make sure oil is always full. You can try switching oil weights. Some say the 30w will stay up there better in cold as where others state 5w will move easier and get where it needs to be faster.

But again ive always hated it when I heard it. Very bad on a forged aluminum piston motor where it takes time for it to heat up and seal and stop knocking away.

 

[19963.4lsr5]

Could be from carbon build up. My oil burning Saturn did that.

 

[dace voit]

I was wondering about piston slap, but it sounds so much like a rod knock that it has me worried. Since it goes away, I pretty much ruled out the knocking rod. I have some BG-44k running through there to see if any build up could be causing this.

 

[kolelt]

I know the 5vzfe are known for TOYOTA TAPPING NOISE mine has like a tapping noise. But nothing like this. I don't know, I'd do some testing to make sure it's all good. Make sure it's not low on oil, check oil, check everything nicely.

 

[19963.4lsr5]

My cold engine carbon knock sounded like it was going to throw a rod out the block and everyone at work would look at me.

The GM aerosol can of upper engine cleaner and a bunch of water washes to steam clean got rid of it.

 

[19bham92]

I was told it was something in the evap system and it's perfectly normal. It usually goes away after reaching OT unless its below zero for mine.

 

[19963.4lsr5]

If it speeds up with engine rpm it's not associated with the evap system.

Mopar used a purge pump mounted on left inner fender that would sound like a rod knock. Soo many people complained about it there was a TSB for replacing the mount for it with one that has double rubber isolation. And when it's below 35 out it still sounds like a rod knock.

But it's a steady sound know matter what engine rpm.

 

[jgue467]

Sounds like

sticking valves to me. I'd try your favorite upper engine lube as stated above and/or seafoam, startron, etc. and run a 5-40 oil. My 01 makes no such noises, just purrs like a kitten.