Engine knocking at startup

blackngoldrules · 08-08-2009, 08:16 PM

Well, I started another thread on here asking about putting a new PCV valve in, which I finally did. I've had a slight knocking when I first start up my truck that eventually seems to go away once it's at normal operating temperature. I was hoping changing the PCV valve might help but unfortunately it's still knocking when I first start it up. What do you guys suggest I try to get rid of the knocking? I use 5W30 oil which is recommended. That's what I've always used. Should I try going a little heavier starting weight like 10w30 since the problem only seems to be when the engine is cold? Should I try sea foam and see if that helps? Maybe I have some carbon buildup in there, I don't know. I just changed my oil about a month ago so I guess I'd have to wait a while before going the sea foam route. Anyway, any suggestions would be appreciated. Thanks.

65fastfalcon · 08-09-2009, 08:02 AM

sounds like you might have some debris/dirt or maybe the oil isn't to the upper part of the motor yet....what size motor do you have?

blackngoldrules · 08-09-2009, 03:42 PM

Quote:

Originally Posted by 65fastfalcon

sounds like you might have some debris/dirt or maybe the oil isn't to the upper part of the motor yet....what size motor do you have?

The motor size is in my signature actually. 3.0 V6 FFV. I've had others suggest to me that it could be a problem with the oil filter's anti drain back valve since I think it's been doing this ever since I last changed my oil. I'm going to stick another filter in there tonight and see what happens. If it still does it then maybe it's CCDI?

blue beast · 08-11-2009, 03:15 PM

make sure you only use Motorcraft filters on the Vulcan 3.0 FL400s or you will get knocking on startup even on other filters with the valve. ONLY MC!! My wally world just had them on discount for $1.00 each but normally they are $4.00 or so and well worth it.

blackngoldrules · 08-12-2009, 05:46 PM

Quote:

Originally Posted by blue beast

make sure you only use Motorcraft filters on the Vulcan 3.0 FL400s or you will get knocking on startup even on other filters with the valve. ONLY MC!! My wally world just had them on discount for $1.00 each but normally they are $4.00 or so and well worth it.

Yeah, I've always used motorcraft FL-400s filters, at least since I've been changing my own oil the past couple of years. I just added some techron to an empty tank and filled it up with BP gas. I did some "spirited" driving for a few miles after that to try and work the stuff into the injectors. I figured I'd try this in case it's CCDI. If it keeps doing it after this then it may be something beyond what I can personally do. We'll see how it goes. Thanks.

blue beast · 08-12-2009, 08:40 PM

Carbon build up would give you pinging on acceleration not on start up. Maybe post up a video of the truck starting to give us a better idea. Are you the type that starts their vehicle and then throws it in gear and goes? It takes a couple seconds for the oil pressure to build up to a comfortable level for me, But to each their own. I always say give at least 20-30 seconds for pressure and oil to get everywhere before taking off.