Knocking at cold startup

[rabidbandit]

Hey guys,

I started my blazer up tonight after drivin' most of the day today and I had a pretty pronounced knocking at idle and when revved. After about 15 sec, it went away and can't duplicate it. I have a fresh oil change with syn. blend (first time switch to syn.) with about 600 on the odo since the switch with a pureoilator filter. Oil drain back issues?, or maybe somethings about to go? It's only done it this once since I've had it for about 8 months. Kinda weird. Any recommendations on brands of oil filters with better flow characteristics? Any info. would be awesome, Thanks

[bvr775]

the service note says to get a check valve oil filter.

[03 Rado]

Its piston slap, not oil drain back and its in the tech articles area. 01-03 had it before GM went with larger diameter pistons due to the complaints! Syn oils and semis make it even more pronounced longer!

[rabidbandit]

Rado,

It's only done it once since I bought it almost 8 months ago. Pretty sure it's not piston slap due to it's infrequency. I'll try another filter with an anti-drain back valve and see if that will keep it from repeating. I guess people change their syn. oil 500miles after they switch because of the carbon it breaks loose...so I'll give it a shot. Thanks for the help guys

[bvr775]

are you under warrenty?

[Sparky2263]

I'd be hooking up a manual pressure gauge quicker than you can say BOO.

[rabidbandit]

The knock was valve train noise...lifters prob.Changed oil and replaced filter with an anti-drain back valve type...the old filter had a defect in the valve. No problems since...and Yes it's under warrantee. If it blows up, a new engine would make me happy again:) Thanks guys

[LEADFOOT]

What kind of filter did you put on it? I asked this question a while back and Jedi master (whom I wish would come back) showed me the difference in all the oil filters. I went to the auto parts store and checked them out myself. I found that besides the K&N filter the AC delco was the best and it is what I use now.

[bvr775]

the filter to stay way from is the puralator filters. These are by far the worst filters on the market.

[03 Rado]

You mean NOT Pure Oil Later!!

[rabidbandit]

I have the tough guard filter. Pressure looks good....also switched to full synthetic oil. If you guys think there is a better filter...I'm all ears. The knock never came back, and runs like a dream:) I'm relatively new to the chevy world...converted ford guy after the horrible nightmare with a few farely new ford rangers. So here I am.

Thanks for all the info. on this site ya'll:D

[Minitrucker]

Glad the knock is gone and that your head cleared up and you came over to Chevy.
lol