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Old 11-11-2012, 02:15 PM   #1
kris's66lwb
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So I got a rod knock!

Put a new base gasket on the ole 400 got her warm and drive to town and hear a noise. Get home rev her up and I put my hand on the intake manifold. Harsh knocking inning from within. What do I do?
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Old 11-11-2012, 02:50 PM   #2
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Re: So I got a rod knock!

Not good. A rod knock is a ticking bomb. Prepare to replace or repair it.

You can easily pull the crank and have it turned for new bearings. I had a 283 in a '77 that spun a bearing. After fixing it, I sold the truck. Last reported, it ran for several years before the truck was not seen again. I replaced the bearings on a picnic table!
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Old 11-11-2012, 02:52 PM   #3
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Re: So I got a rod knock!

I think I over sped it I replaced the gasket reved it up it was blowin black smoke from all the unburnt crap in the system that's built up. The I drive it and its there only under heavy load or high rpms in park
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Old 11-11-2012, 03:02 PM   #4
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Re: So I got a rod knock!

Base gasket? For the carb? If you have a rod knock for sure then your engine needs a teardown and rebuild
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Old 11-11-2012, 04:00 PM   #5
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Re: So I got a rod knock!

It's comming from te block after I reved it up I'm so pissed at y self right. Ow
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Old 11-11-2012, 06:13 PM   #6
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Re: So I got a rod knock!

Started it up it knocks on start up and light throttle now
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Old 11-11-2012, 06:52 PM   #7
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Re: So I got a rod knock!

You should park it and start the teardown before you window the block.
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Old 11-11-2012, 07:03 PM   #8
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Re: So I got a rod knock!

It's parked I havent even transferred the title so I guess I should rebuild the whole thing and tips or tricks to add in during the build ? I want a stout engine but I need to pass smog for the time being
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Old 11-19-2012, 04:37 PM   #9
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Re: So I got a rod knock!

ok so i took of the left valve cover and all th epush rods look ok i cranked it over to seeif the noise was still audable it actually ran pretty well on the right bank only id idled for about 3 mins the knock was gone but had a faint tick from the right bank it would rev up a bit and it wasnt knocking so my question is if the knock goes away with out spark what is it ? is that a bering piston slap i was idling at about 550 rpm it was knocking at that rpm faintly when the cover was back on and all the plug wires were on
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Old 11-19-2012, 04:43 PM   #10
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Re: So I got a rod knock!

should i drop the pan and see what bering is messed up and see how far the rod and journal are out of spec ?
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Old 11-19-2012, 05:08 PM   #11
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Re: So I got a rod knock!

either way the engine will need to be pulled so why not just pull it and inspect on a stand??
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Old 11-19-2012, 05:11 PM   #12
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Re: So I got a rod knock!

Piston s knock goes away after a minute so I would say be safe and drop the pan. Prob better to pull the engine since if it is bad you will Prob have to pull it anyways
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Old 11-19-2012, 05:16 PM   #13
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Re: So I got a rod knock!

See I'm not in a postion to pull it I have no concrete or a garage I'm doing all this in the mud of my house I can drop the pan with it in the truck I think seeig as its a 4x4
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Old 11-19-2012, 05:22 PM   #14
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Re: So I got a rod knock!

Well go ahead and do that. But if it comes to the point a rod bearing is spun causing a knock the crank will have to come out
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Old 11-19-2012, 05:31 PM   #15
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Re: So I got a rod knock!

^^^ Ditto as long as the bearing hasn't spun
Pull the pan and see which rod is bad, I did this on a 350 in a 89 K2500,
slapped a new bearing in it and beat the snot out of it plowing snow.
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I put a chevrolet tailgate on my last truck and it started acting like a girl...love me, need me, want me pay attention to me. Took it off and put the GMC back on (fixed the latch) and it went back to being the same old dirty bastard it used to be
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Old 11-19-2012, 05:46 PM   #16
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Re: So I got a rod knock!

Idk how bad it is yet ill tear it apart tonight and post some pics
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Old 11-19-2012, 05:59 PM   #17
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Re: So I got a rod knock!

Its a bad idea to keep driving with any type of knocking. I'd highly recommend checking it out ASAP.

This is the result of a rod knock that "I'd get to someday"

Marked the crank up pretty bad, busted the cam and destroyed the block when the other part of the rod flung around. And it was a long ass walk home lol 13 miles..
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Old 11-19-2012, 06:42 PM   #18
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Re: So I got a rod knock!

Ok got te pan down and I found what appears to be rocks? Or chucks of black hard stuff it's not metal none of the rods show obvious signs of issues every thing looks normal cyl walls look ok pistons look ok from the bottom
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Old 11-19-2012, 06:48 PM   #19
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Re: So I got a rod knock!

Mine looks 100% normal no obvious signs of damage on the bottom end
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Old 11-19-2012, 07:51 PM   #20
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Re: So I got a rod knock!

Could be excess black rtv from motor assembly.

If the rod bearings look, maybe it's a carbon knock or wrist pin.
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I put a chevrolet tailgate on my last truck and it started acting like a girl...love me, need me, want me pay attention to me. Took it off and put the GMC back on (fixed the latch) and it went back to being the same old dirty bastard it used to be
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Old 11-19-2012, 07:52 PM   #21
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Re: So I got a rod knock!

Is it auto or std trans?

Could be a broken flex plate which will sound just like a rod knock.
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I put a chevrolet tailgate on my last truck and it started acting like a girl...love me, need me, want me pay attention to me. Took it off and put the GMC back on (fixed the latch) and it went back to being the same old dirty bastard it used to be
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Old 11-19-2012, 08:46 PM   #22
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Re: So I got a rod knock!

It's an auto ill look when I have more free time
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