390 nocking
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Senior User
Joined: Apr 2005
Posts: 204
Likes: 1
From: Gillette, wy
390 nocking
73 f-250 390
My water pump started puking water out the weep hole so I decided to put a new one on. While I was there I resealed the timing cover and the oil filter housing, since they were leaking oil like the valdeez. I also changed the oil(always use 15w40) I took it for a spin down the highway for about 10 miles, i heard a light nocking sound at an idle when I turned to go back to town. I checked the oil, it was good. Oil pressure was about 25lbs at an idle. So I figured it was just a fluke. So i turned around and headed back to town. I pulled up to my house and it was nocking really loud, and I had no oil pressure at an idle. I shut it off, checked the oil and it was still full.
The nocking was really loud on the bottom of the engine, there was no noise coming from the top. I let it cool off for about an hour started it back up and I had 25lbs of oil pressure and no nocking.
This motor usually runs 45lbs of oil pressure cold and 25 hot. It just kinda struck me as wierd that it lost oil pressure. Guess i'm just not sure what would cause this. Maybe i got a piece of the old gasket into an oil passage or something. If someone could help me out i would appriciate it.
My water pump started puking water out the weep hole so I decided to put a new one on. While I was there I resealed the timing cover and the oil filter housing, since they were leaking oil like the valdeez. I also changed the oil(always use 15w40) I took it for a spin down the highway for about 10 miles, i heard a light nocking sound at an idle when I turned to go back to town. I checked the oil, it was good. Oil pressure was about 25lbs at an idle. So I figured it was just a fluke. So i turned around and headed back to town. I pulled up to my house and it was nocking really loud, and I had no oil pressure at an idle. I shut it off, checked the oil and it was still full.
The nocking was really loud on the bottom of the engine, there was no noise coming from the top. I let it cool off for about an hour started it back up and I had 25lbs of oil pressure and no nocking.
This motor usually runs 45lbs of oil pressure cold and 25 hot. It just kinda struck me as wierd that it lost oil pressure. Guess i'm just not sure what would cause this. Maybe i got a piece of the old gasket into an oil passage or something. If someone could help me out i would appriciate it.
Thread Starter
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Senior User
Joined: Apr 2005
Posts: 204
Likes: 1
From: Gillette, wy
Well, i'm pulling the motor this weekend. The knock shows up only when the engine gets warm at all rpm ranges. I'm almost certain that I got a piece of something in the oil gallery blocking oil to crank rod/rods. I'll just do a rebuild with it apart. What gets oiled first after the oil goes through the filter? just so I have an idea where to look first.
Lead Driver
Joined: Jan 2003
Posts: 9,893
Likes: 12
From: Ohio
Oil goes up to the CAM first, then down to the mains/up to the heads. If you pull the front cover, you'll see the casting that runs from the oil filter housing area up to the front cam area(actually to the center oil valley that runs front to back).
It doesn't take much to loose enough oil to the rods to make it start knocking, especially on an older engine. The rods are the LAST thing that gets oil. No saving it after the fact.
It doesn't take much to loose enough oil to the rods to make it start knocking, especially on an older engine. The rods are the LAST thing that gets oil. No saving it after the fact.
Posting Guru
Joined: Aug 2005
Posts: 1,036
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From: NE Ga
Well I've got my rockers restricted down to 7/32"? hole. I installed those before finding some fingered rails so would I be better off taking out the restrictors now so I don't have rod prob's? I didn't realize they were the last to get lubed.
