Hey Doc
, The block was cut .090, the head .030, cam is .465 earson e470621 grind tq 20 m. Just thought it odd its happening now and only one cylinder.
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| pushrod bending https://slantsix.org/forum/viewtopic.php?t=52141 |
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| Author: | Dizzydean [ Mon May 20, 2013 10:25 pm ] |
| Post subject: | pushrod bending |
So my motor has about 3k miles on it and all of a sudden within the last month the #4 cylinder has bent 2 intake pushrods. when this happens the exhaust rod doesn't get bent just comes off and the lifters are laying in the galley. I can tell cause it will run like a plug wire is off. Its been running fine up until now and nothing has changed and no other cylinder is doing it. puzzling.. Any ideas/suggestions??? |
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| Author: | slantsik [ Tue May 21, 2013 2:48 am ] |
| Post subject: | |
My guess would be your exhaust valve sticking when un- seated. the rocker arm would then be loose and the push -rod falls out. The bent intake rod may be because the intake valve is hitting the stuck exhaust valve and cannot un seat fully,maybe. A vacuum gauge may help diagnose this . see scenario #5 at this link. http://www.secondchancegarage.com/public/186.cfm Just my guess ,maybe someone has abetter Idea Brendan. |
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| Author: | Fopar [ Tue May 21, 2013 1:04 pm ] |
| Post subject: | |
The valves are side by side no way for one to hit the other one. Richard |
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| Author: | slantsik [ Tue May 21, 2013 3:26 pm ] |
| Post subject: | |
Quote: The valves are side by side no way for one to hit the other one. Correct, I just checked and there is no way. So the intake valve is sticking too? Maybe soft or broken springs causing valve bounce/ float at high RPM? Brendan. |
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| Author: | ceej [ Tue May 21, 2013 4:30 pm ] |
| Post subject: | |
I'd check to see if the rocker shaft was over-tightened. The rocker shaft could be deformed causing bind around those rockers. CJ |
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| Author: | Dizzydean [ Tue May 21, 2013 5:26 pm ] |
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Thanks for the input so far. The puzzling part is this is a fresh motor and have had no problems like this until now. I can actually hear the tapping like its loosening up when I drive then the odd thin metalic like sound then the rough running and I know its happened again. If it was a geometry issue wouldnt it of done so at the beginning? |
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| Author: | Doc [ Tue May 21, 2013 5:31 pm ] |
| Post subject: | |
How much lift are you running? Was the head or block milling a lot? DD |
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| Author: | Dizzydean [ Wed May 22, 2013 4:34 am ] |
| Post subject: | |
Hey Doc , The block was cut .090, the head .030, cam is .465 earson e470621 grind tq 20 m. Just thought it odd its happening now and only one cylinder.
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| Author: | Louise76 [ Wed May 22, 2013 6:08 am ] |
| Post subject: | |
Just a loose untrained thought: but in airplane engines when this happens shortly after overhaul, it is often from the clearance between the valve and guide being too tight. If the sticking happens AFTER the engine warms up fully, that could be the case. On some airplane engines, if the valve to guide clearance is too loose (worn), oil gets onto the valve stem, burns and cokes up, and then the valve sticks in the guide intermittently AS the valve gets hot but the engine and guide are still cold. Then after the guide warms up, the sticking usually goes away. We call that morning sickness. I'm not a /S engine overhaul expert, so I'll try to keep watching this conversation to see what you guys discover. P. |
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| Author: | SpaceFrank [ Wed May 22, 2013 7:10 am ] |
| Post subject: | |
Check to make sure you're getting enough oil on the top end? I assume your valve lash is set properly. |
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| Author: | Doc [ Wed May 22, 2013 8:34 am ] |
| Post subject: | |
At .465 lift... inspect for coil bind and retainer contact with the top of the valve guide(s). DD |
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| Author: | Dizzydean [ Wed May 22, 2013 1:09 pm ] |
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I will check since i need a new gasket anyway. Its going to be a couple weeks were headed on vacation and dont want car issues coming with me. Ill keep you guys posted when we get back. Thanks |
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