Rebuilt Motor Knock
#1
Rebuilt Motor Knock
I just completely rebuilt my magnum 360. All new bearings, pistons, etc. Well it makes a small knock at idle. Can hear it louder from under the truck. Almost can't even hear it from above. It's a rhythmic noise that will raise with rpms. Doesn't get louder, just goes up. Can't even hear it driving. Any simple things it could be? Oil pressure is good. Almost sounds like rod knock even though I replaced those and they all measured great. Any help is welcome. I'm at a loss right now
#2
#3
I did replace the pistons and used the standard bore. The machine shop said it was not worn too bad. They did hone it. They also checked over the crank. That was good to go. Idk what it could be. I thought I did this all right... maybe I will check the flex plate but bolts but I just put those on today...
#4
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#6
ok well I have an update. Started it up today and ran it for a bit. Noise is barely there now. If I didn't hear it yesterday, I wouldn't have heard it today because u have to be right under the oil pan to hear it. Had a retired mechanic come and listen with a stethoscope. It is coming from the front right of the oil pan area. That's the only place he could hear it. Not the block or anywhere near the top of the engine. Not even on the underside or left side of the oil pan. It's so quiet he said to run it and keep a close ear on it. Worse case scenario I pull the pan and replace the front 4 cylinder rod bearings. I can do that easily. For now I'm going to drive it and if it gets to the point I can actually hear it when walking around the truck, I'll drop the pan. Also going to do an oil analysis after the second oil change. We basically came to the conclusion the only thing it could possibly be is one of the front rod bearings didn't get enough oil on yhe first startup and maybe wore a little bit. Will update this thread if something changes.
#7
ok well I have an update. Started it up today and ran it for a bit. Noise is barely there now. If I didn't hear it yesterday, I wouldn't have heard it today because u have to be right under the oil pan to hear it. Had a retired mechanic come and listen with a stethoscope. It is coming from the front right of the oil pan area. That's the only place he could hear it. Not the block or anywhere near the top of the engine. Not even on the underside or left side of the oil pan. It's so quiet he said to run it and keep a close ear on it. Worse case scenario I pull the pan and replace the front 4 cylinder rod bearings. I can do that easily. For now I'm going to drive it and if it gets to the point I can actually hear it when walking around the truck, I'll drop the pan. Also going to do an oil analysis after the second oil change. We basically came to the conclusion the only thing it could possibly be is one of the front rod bearings didn't get enough oil on yhe first startup and maybe wore a little bit. Will update this thread if something changes.
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#8
Yep... (sorry I'm going half glass empty here) but worser case scenario, the journal gets buggered while you delay, and you end up having to pull the crank to grind it. I'd pull the pan and find out, but I'm neurotic, lack patience, and never rely on hope as a plan :-) Good Luck !
#9
#10
all pistons and wrist pins were replaced and the pins well oiled before install. All bearings were coated in tons of assembly lube. Completely filled the oil filter before startup and ran the engine over without plugs and injectors disconnected to get at least some oil moving. Really don't understand how the noise came about as I was careful with everything but crap happens I guess. Rod bearings are on the way.