This is definitely piston noise in this thread, not lifter noise.
Also, if the filter is loose I would think you'd have a leak on your hands.
I'm still looking for BG44K. My local parts store doesn't have it.

 

My local car parts store did not have them. I did a search using their website and found an Acura dealership nearby who sells it.

 

EVRose,
Try the manufacturer's web site search tool :
http://www.bgfindashop.com/locator/index.php

 

Cool. There's a shop right down the street. Thanks Mike and ZBEE.

 

As much as I hate to bump a month old thread, I just want to say I came searching for this "knock" as well. The Vette had been sitting in a heated garage for a couple weeks and it seemed to knock a little when I started it today and had me concerned. I am used to a knock when some cars first start after sitting, but they normally go away after 1-2 seconds. This didn't go away immediately. Now I can sleep better knowing that it might be normal.
I love it when I can find EXACTLY what I am looking for on the forum.
Thanks guys!

 

My 03 always made a little engine tapping for a couple minutes before warm but would then go away.

 

Just a quick update - the weather has turned a lot colder here in SC ( 25 - 35 F) and I can still detect a very very slight tapping for about a minute or so after startup, but it is much quieter than before using the BK44. Fortunately it goes away completely once the engine begins to warm so I am convinced it is nothing serious. The "performance enhancer" seemed to work, much to my surprise.

 

I'm also experiencing the same noise on my '05 Z51. I would describe the noise as a light rod or wrist pin knock. It's a daily occurrence every time I start it cold. I've had this car since christmas eve and noticed it shortly after as the weather here in central Florida has gotten much colder (28 degrees by morning). I was really concerned about it but feel much more at ease with the information this great group of people has provided. I will be heading out tomorrow to pick up some BG44K from a place close by to see how it does.

Thanks so much for putting this out here !!!

 

Six weeks after two treatments of BG 44k power enhancer to remove carbon build up, the piston slap has not returned at cold start up. Keeping my fingers crossed

 

My '06 does not knock at all but I test drove an '05 that sounded like a diesel at start-up. I think it's just the nature of the beast but varies a lot from vehicle to vehicle.

 

Well, I'll add this to see if it coincides with anyone's experience. My '08 has 31K miles/39 months (and 1000 miles on the oil change), and it started up today with a knock so loud that even inside the car it made me jump to turn it off quickly. After thinking about it for a few minutes and looking under the hood for a belt that was flapping around (that was the noise level), I restarted it. Same noise, quickly shut it off. I thought about it longer this time, but tried it again after an hour. It started with the same loud knock but began softening quickly, and by 30 seconds was gone. Restart 2 hours later: no knocking, same as every time before today. I will be trying to find some pattern if/when it happens again.

I owned a '98 for 10 years and never heard any more than a light ticking or tapping. And never heard anything in this one prior to today. It has been sitting a lot for the past month (100 miles) and the last time I had it out of the garage was to wash it 2 days ago - maybe out 20 feet and in 20 feet. Temperatures here in SC have been mild - 50-70F lately.

 

Yup...My '99 Camaro did the same thing. The LS1 was even worst.

It's piston slap.

 

Pretty sure the GM piston slap you;re talking about doesn't apply to our engines but engines they tried to develop with very short skirts. AFAIK the vette has regular pistons with regular skirts.

 

I have an 07', bought new and I've developed a knock on cold start up. The noise started a little over a year ago. It's not valve train, it's deeper in sound and a singular knock. But, the odd thing is, that, it doesn't make a sound at idle, only when I put it in gear and drive the car. Once the engine heats up a bit, it goes away. There's no sound with warm temps, just below 45 degrees. I've been told it's normal and I've got the 5 year engine etc. warranty plus I've the GMPP extended warranty, so, if it blows it's on them.

 

Wow, I too am somewhat relieved. From the day I purchased my '00 4 weeks ago, I heard a slight tick at cold start up, but it usually goes away after it the engine warms a little. Keep in mind that by cold here in So Ca I mean 40-50 deg night temps.

My first thought was it sounded like a lifter, but after reading some of the other posts, I'm hoping it's just an inherent design bug and nothing major. Hopefully, those that tested the additive will continue to provide a follow-up to this post...I'm thinking of buying some myself.

 

Mine started doing this recently, while cold and under (slight) load. It just turned over 49K miles. By cold I mean after sitting overnight in high 60s/low 70s. However, it stops by the time the coolant temp reaches about 125F.

As a result I altered my commute to coast downhill for the first mile of my morning commute, vice going up a few steeper grades.

Perhaps I should try this BG44 stuff?

 

It is worth a try! If the knock is carbon build up related, a couple of treatments will reduce or illiminate the knock. It worked for me. However, it will not help piston slap due to loose tolerences, nor does it claim to. Good luck, I hope it works for you