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| Rod Knock, Sometimes... https://slantsix.org/forum/viewtopic.php?t=52726 |
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| Author: | ValiantBoyWonder [ Sun Jul 14, 2013 12:12 pm ] |
| Post subject: | Rod Knock, Sometimes... |
The engines been making a slight ticking/clicking noise recently. The valves have been adjusted properly, rocker arms, adjusting screws, springs, lifters, push rods and fuel pump all check out okay. If i pull the #6 plug wire the sound goes away. My oil pressure is between 40psi and 60psi during idle and acceleration. If it's a cold morning, the engine will click slightly louder, and as it warms up the clicking will die down. The strange thing is, that often times, the car will not make a sound at all and be perfectly quiet for a couple days, then the oil will run to about halfway on the dipstick (bad valve guides) and it'll start in. It quiets down in a couple days and the cycle starts again. there was some bearing material in the oil awhile back, not very much, but enough for me to notice, funny thing is, that was 1,000 miles before it started clicking. bad wrist pin or rings? or too much bearing clearance? maybe even the bad valve guides? (if the plug wire was pulled for that bad guide, would it stop making noise?) i use a wix filter, running rotella oil, compression on all cylinders checked out at 135. mystery. |
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| Author: | Reed [ Sun Jul 14, 2013 12:17 pm ] |
| Post subject: | |
What weight oil? |
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| Author: | ValiantBoyWonder [ Sun Jul 14, 2013 12:32 pm ] |
| Post subject: | |
rotella 15w40 |
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| Author: | Reed [ Sun Jul 14, 2013 12:51 pm ] |
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Good grief. Why so thick? Try 5W-30. The thicker the oil the harder it is for it to get into the tight clearances in the motor. You only need something like 6 PSI at idle when the motor is hot. Using too thick of oil can lead to oil starvation in tight clearance areas especially when the motor is cold. It also leads to decreased engine efficiency since the motor has to push all that thick oil around and out of the way. |
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| Author: | ValiantBoyWonder [ Sun Jul 14, 2013 1:09 pm ] |
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i used the 15w40 figuring that the clicking might be from worn rod bearing. The thicker oil would substitute for the bearing being worn. At this point i'm willing to try anything before dropping the pan and having a look around. so the thicker oil has to have more time to warm up and get loose, which would mean those bearing clearances are oil starved for a moment until things start getting warm? Regardless of that this would be a tell tale sign that those bearings are on their way out? is there another test i can conduct that will tell me for sure it's the #6 rod bearing? |
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| Author: | robertob [ Sun Jul 14, 2013 2:07 pm ] |
| Post subject: | |
Rod knock is engine speed, valvetrain noise is 1/2 engine speed. Rod knock is loudest in overrun, when you let off the gas at a high speed. |
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| Author: | ValiantBoyWonder [ Sun Jul 14, 2013 2:36 pm ] |
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Quote: Rod knock is engine speed, valvetrain noise is 1/2 engine speed. Rod knock is loudest in overrun, when you let off the gas at a high speed.
aha! the clicking is at half speed and under load, and when i let off the gas and coast, she doesn't make noise at all. to test this, if i were to pull the pushrod for the offending valve and let the engine idle, the sound would go away correct? |
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| Author: | SlantSteve [ Sun Jul 14, 2013 4:03 pm ] |
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I know it sounds like you most probably have some major surgery on your hands, but have you had a look for a leaking exhaust manifold? They can make a real ticking sound under load and go quiet when you reduce power as well as being noisy when colder.... Worth a look before you get too far involved pulling it apart! It might get you out of trouble for a while longer, but if you found metal, burn oil etc I think you may have a bigger job on your hands.....good luck! |
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| Author: | robertob [ Sun Jul 14, 2013 6:24 pm ] |
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clicking half speed and under load says 'cracked exhaust manifold' to me too. Or a leaking gasket. |
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| Author: | ValiantBoyWonder [ Sun Jul 14, 2013 10:59 pm ] |
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But would shorting one wire reduce the noise of an exhaust leak dramatically? |
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| Author: | emsvitil [ Mon Jul 15, 2013 12:36 am ] |
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Quote: But would shorting one wire reduce the noise of an exhaust leak dramatically?
Yes. Unburned mixture (no spark) has less volume and pressure to make any noise. If you've run an engine without an exhaust system, it isn't loud until after it starts............ |
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| Author: | Reed [ Mon Jul 15, 2013 8:47 am ] |
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Quote: i used the 15w40 figuring that the clicking might be from worn rod bearing. The thicker oil would substitute for the bearing being worn
No, the thicker oil actually has a harder time getting in between the bearing surfaces. Counterintuitive but true.Try dropping down to 5W-30 for an oil change and see what happens. |
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| Author: | wjajr [ Mon Jul 15, 2013 11:26 am ] |
| Post subject: | |
15w40 oil; first number (15) is its cold viscosity; second number (40) is viscosity at full operating temperature. 15 weight oil is a bit on the thick side for an engine within spec tolerances when cold and one reason when cold you have high oil pressure. Clicking is often top end noise from lack of lubrication. It is hard to get thick oil to pass through the small passages in rocker arms to push rods when cold. 10 or as Reed recommended 5 weight will get lubrication to rocker assembly within a second or so after a cold start in summer. If a thinner weight oil does not reduce the clicking or ticking, remove rocker assembly keeping all rockers in order they were found so each one returns to its correct valve, clean out rocker’s oil passages with carb cleaner, compressed air, and flush rocker shaft; see if that helps. |
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| Author: | ValiantBoyWonder [ Sat Jul 20, 2013 11:27 am ] |
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Since the guides were shot, the engine consumed oil and fouled plugs like a she devil until I switched to thicker oil, but as a result, the guides are getting worse due to lack of oiling. I have a head ready to go on, but if the bottom ends got problems then I don't want to rush it. I plan on changing the cam with the head, so I'll pull off the oil pan and check it out. Against everyones advice, I'm going to both pull the oil pan and change the cam with the engine in the car. Pray for me. As for the exhaust leak, I do have one where the manifold to pipe junction. Just for kicks, I'm going to change the gasket and we will see if the results for the test change. |
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