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| Knocking slant 6 https://www.slantsix.org/forum/viewtopic.php?t=68194 |
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| Author: | magin [ Mon May 05, 2025 12:41 am ] |
| Post subject: | Knocking slant 6 |
Hi guys, wondering if anyone has any idea why way Aussie slant 6 has a knocking noise, issue is before it reaches operating temperature it runs with no noise soon as it warms up it start to knock when idling rev motor and it goes away, noise is coming from the the front of motor near timing gear changed timing gear that’s ok oil pressure is fine run out of ideas thanks in advance |
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| Author: | Dart270 [ Mon May 05, 2025 5:19 am ] |
| Post subject: | Re: Knocking slant 6 |
Two initial thoughts: 1) Check crankshaft end play. Pry gently on the damper with a prybar or long screwdriver, then push the crank backward and see how much play. Factory spec is 0.010" max, but it can be a bit higher and not cause trouble. 2) I cracked the damper (harmonic balancer, with pulley machined into it) once by installing it improperly. It cracked through the keyway and made a bad knocking sound. You can see if the damper comes off easily or wiggle it off axis to look for flexibility. Not likely this, but easy to check. It's also very possible it's a bad rod bearing. It will make less noise when cold and the oil is more viscous. That will require full engine removal and disassembly, and likely rebuilding. Lou |
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| Author: | SlantSixDan [ Mon May 05, 2025 11:27 am ] |
| Post subject: | Re: Knocking slant 6 |
Need more info — preferably a video with good sound so we can hear what you're hearing. "Knock" could be a lot of things. Could be bearing knock, could be crank end-play as Dart270 describes. Could be piston slap (annoying but harmless). Could be fuel pump rap, which shouldn't be temperature-sensitive but sometimes is. |
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| Author: | magin [ Mon May 05, 2025 5:22 pm ] |
| Post subject: | Re: Knocking slant 6 |
Hi thanks for the advice thought that I might give you a little background with engine. Engine was fully re built with new camshaft, valves, pistons and rings, bearings etc. this issue started about 1200miles noise would only happen when car was warmed up and in drive and stoped. Had the engine was taken apart by same guys and found nothing wrong with engine but no sooner did I drive out noise came back. Since then the noise still comes in when engine has warmed up but know it does not need to be in drive but still needs to be idling. Changed oil pump and fuel pump timing gear Noise appears to be coming from front of engine near timing case, could this be camshaft issue being that this was replaced? |
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