Engine knock for a couple seconds at startup?

ESPZ71 · October 17, 2002

I searched, but didn't find anything like my problem. When I first start the truck, then engine will knock for a couple seconds until the oil press gauge goes from 0 to normal. At zero, it knocks. Is there something I need to replace? Or is that just typical? Lemme know how I can fix it if possible.

ktmps · October 17, 2002

It happened to mine at around 35,000 and around 53,000 I switched to 10-40w it has stopped for now. From what I have heard GM Titghtend up tolerences in the 2001-3 Lower bearings, Mine sounded almost like piston slap, Very noisy in the winter cold starts.

ESPZ71 · October 17, 2002

hehe, mine's got a few more miles....like 105k.

It's a '95 and I was hoping there was something I could do about it. Next oil chg I'll try a diff weight like you mentioned, but I'm skeptical that will fix it. Let's hope so. Thanks for the input dood. ;)

bassdog · October 18, 2002

ESPZ71-

I had the same problem with my 94, ended up being a bad bearing and the oil pump was on it's way. I changed the motor and the problem is gone.

If you're going to try a diff weight, throw in some 20-50, that'll quiet it right up!

chevy4x4trucks · October 18, 2002

It's cold "Cold Start Knock" and is very typical among trucks, cars, vans, etc... There is a technical explanation about it, something to do w/ oil flowing back into the pan when the truck sits. I think CMNTMXR81 explained it on here once or twice before. I wouldn't be too concerned about it. If you checked everyone on your block in the morning you'd find that most of them probably have it to a certain extent. My GTP hasn't done it yet, but its been garaged overnight so it doesn't get below 50 in there.

nator · October 19, 2002

Don't if this applies, but when I purchased my 94 new, it had a flyer in the manual that stated that there was a change in the specs for the oil filter. It stated that GM wanted owners the make sure to use AC oil filter PF1281 (not sure about this number) instead of the PF35 that was called out in the manual. It went on to say that it was to address a problem with oil drain back that was occuring with the 5.7 liter.

Even though I used the filter they specified, I still noticed a little knock once in a while when I started the motor, especially when it sat for a long while without being started.

ESPZ71 · October 19, 2002

Hmm, I'll be sure to check that out too. At this point I'm looking into every angle possible. Surely I'll figure something out if I keep trying.

l83corvette · October 25, 2002

This is a bit off topic But what oil pressure are You guys running?

ESPZ71 · October 25, 2002

Mine varies so much that I cna't even tell what "normal" running pressure is. When it's idling, it drops to zero and my check engine light comes on, when I'm driving it's in the 40 range I think. ???