I'd end the suspense and just pull the rod caps and look. Wouldn't be the first time an engine got stuck together with std. bearings on a turned crank.
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| Author: | bwhitejr [ Mon Oct 17, 2005 4:10 am ] |
| Post subject: | Knocking sound after rebuild! |
I have just received my block back from the machinist. There are no lifters installed, no fuel pump installed, no pushrods, no top end, no flywheel. Just crank, rods, pistons, camshaft, timing chain and gears. When I turn the engine, every time cylinder 2 and 5 come to the top, there is a knocking sound and the crank has some slack in it. The faster I turn it (by hand) the louder it is. Is it the rod bearings, the main bearings or the wrist pin? Thanks in advance, bwhitejr |
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| Author: | 64 Convert [ Mon Oct 17, 2005 5:09 am ] |
| Post subject: | |
If the bearings are indeed installed and the bolts tightened, there should be no knocking noises! Verify that you can see the bearings and that there is no slack in the timing chain. Then re-torque the rods and mains and get back with more info. |
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| Author: | bwhitejr [ Mon Oct 17, 2005 5:15 am ] |
| Post subject: | Knocking Noises |
The timing chain and gears are new Cloyes double rollers. Good and tight. It feels like (I have no experience with this) that one of the old bearings was put in by mistake after the journal was cut down. |
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| Author: | 64 Convert [ Mon Oct 17, 2005 7:26 am ] |
| Post subject: | |
I used to check for a bad rod bearing, with the engine in the car, using a piece of wood and a hammer. Put the wood on the rod cap and tap the end of it with a hammer. If you have a bad bearing, you can usually hear a hollow sound that isn't there with a good bearing. It's crude, but oftentimes effective. Actually, if it was me, I'd pull all the rod caps and give the crank and bearings a good visual check. If they look okay, I would still check the clearances with Plastigage. |
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| Author: | Dennis Weaver [ Mon Oct 17, 2005 8:08 am ] |
| Post subject: | Re: Knocking Noises |
Quote: The timing chain and gears are new Cloyes double rollers. Good and tight. It feels like (I have no experience with this) that one of the old bearings was put in by mistake after the journal was cut down.
...you'd never notice .010" or .020" difference turning the crank by hand. Was it bored? Are the ring ridges still there?D/W |
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| Author: | Rob64GT [ Mon Oct 17, 2005 8:21 am ] |
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Dennis is on the right track, if the engine wasnt bored its probabily the ring/rings hitting the ridge. I removed the ridge on a datsun engine with sandpaper not very percise but it worked. |
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| Author: | bwhitejr [ Mon Oct 17, 2005 8:21 am ] |
| Post subject: | Knocking Noises |
Yes it was bored, but there are no ridges. All the cylinders are smooth all the way to the top. And the only pair of pistons that make a noise when you rotate the engine 360 degrees is the 2 and 5 cylinders. And only when they are TDC. There is a little play at TDC when 2 and 5 are up that isn't there on the other cylinder's TDC. It seems that the wrist pin would be the problem (but, I am new to this). |
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| Author: | Rob64GT [ Mon Oct 17, 2005 8:28 am ] |
| Post subject: | |
If its not the ridge I would use a plasti gauge to check the bearing clearance. If the clearance is OK I would pull the piston and inspect it. |
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| Author: | Dennis Weaver [ Mon Oct 17, 2005 8:43 am ] |
| Post subject: | |
Where are you sensing the play? Couldn't be at the crank, there are four other rods hooked to it, too, there'd have to be slack in all 6. If it bothered me, I'd pull at least the caps on those and inspect, possibly pull the questioned pistons as suggested above. It could be the wrong rings. I don't know what your sensitivity threshold is to a "knock" when turning a new motor over by hand, but it could be that it is nothing. D/W |
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| Author: | bwhitejr [ Mon Oct 17, 2005 9:33 am ] |
| Post subject: | Knocking Noises |
It is fairly subtle turning the engine at ratchet speed, but when you go all the way around fairly quickly it definitely knocks. |
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| Author: | slantzilla [ Mon Oct 17, 2005 1:02 pm ] |
| Post subject: | |
I'd end the suspense and just pull the rod caps and look. Wouldn't be the first time an engine got stuck together with std. bearings on a turned crank.
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| Author: | bwhitejr [ Mon Oct 17, 2005 3:27 pm ] |
| Post subject: | Knocking sound after rebuild! |
Could it possibly be that when 2 and 5 are TDC that 3 and 4 are BDC and are hitting my dip tube for my oil pump? |
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| Author: | Dennis Weaver [ Mon Oct 17, 2005 3:40 pm ] |
| Post subject: | |
You never mentioned that the pan was buttoned up. Yes, it very well may be that something is amiss in there. Pull the pan and look if you are concerned. D/W |
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