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| loud ticking under load https://slantsix.org/forum/viewtopic.php?t=58214 |
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| Author: | '67 Dart 270 [ Sun Aug 09, 2015 3:41 pm ] |
| Post subject: | loud ticking under load |
OK, so I thought that I was dealing with an exhaust leak, but I'm fairly sure that isn't it. I've reworked my pipes a couple times to move them up toward the body (they were too low) and I replaced a ball joint flange with a V-band flange, so I'm pretty sure it's not an exhaust leak, but I can't be totally sure. I don't hear the tick at idle, and I've checked and rechecked the exhaust manifold and my down pipes at the flanges for leaks, can't find any signs of leakage. When I'm going up a steep hill and have load on the engine it is making a really strong ticking/pinging sound. It sounds really bad, like something is wrong. But, when i'm on level ground or down hill, I can only hear the sound when I'm near a wall or another car, so it's faint enough that it has to reflect off something before I can hear it. When I punch it down I hear it more clearly, and as I said, up hills it gets really loud. I pulled the torque converter cover plate, the flex plate looks OK. I pulled the starter and the cover plate isn't scratched, so the flex plate bolts aren't touching it under load (I was convinced this might be the issue). Any other ideas? The engine only has about 1000 miles on it, and I didn't notice this sound in the first few hundred miles or so or during break in. I noticed in the first oil change after break in there was still some metal "fuzz" on the magnetic oil plug, but that seems to have diminished over the past couple weeks. I changed the oil again today and the oil plug had minimal material on it. I did note a lot of pearlescent material in the oil though, seemed like a lot to me. There were also a couple of small metal bits here and there. I tore apart the filter and there wasn't much to speak of, just the pearly stuff in the oil. Given my history, I pulled the dizzy and the cam gear and oil pump gear appear to be in good shape. The rear seal is leaking a bit, otherwise no symptoms that I can think of. I'm worried... brian |
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| Author: | Reed [ Sun Aug 09, 2015 4:16 pm ] |
| Post subject: | |
Preignition? |
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| Author: | SlantSixDan [ Sun Aug 09, 2015 4:36 pm ] |
| Post subject: | |
Could still be an exhaust leak at the manifold-to-head junction. |
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| Author: | Reed [ Sun Aug 09, 2015 5:33 pm ] |
| Post subject: | |
Or a cracked exhaust manifold. |
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| Author: | '67 Dart 270 [ Sun Aug 09, 2015 6:25 pm ] |
| Post subject: | Ok |
I suspected exhaust, so yes, I dive back in there and try again to find a leak...thanks guys. I have the timing set to about 10 degrees advanced (without vacuum) and it runs good, starts quickly, idles smooth, lots of power. Reed, explain pre-ignition to me, thanks. Brian |
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| Author: | Reed [ Sun Aug 09, 2015 7:35 pm ] |
| Post subject: | |
Pre-ignition, a.k.a. "pinging," is when the fuel/air mixture ignites in the cylinder too early. It makes a distinctive high pitched rapid clacking or knocking noise in the cylinder head. Pre-ignition occurs under several conditions: (1) carbon buildup in the cylinder head which can get hot through the combustion process. Hot enough to ignite the fuel air mixture before the spark plug fires. This could be through too lean of a mixture, too heavy of a load placed on the engine leading to overheating (think big truck hauling heavy load up a hill on a hot day). In fact, even if the cylinder chamber has no carbon buildup overheating can cause preignition. (2) timing that is too far advanced. (3) an engine that has too high of compression for the fuel being used. The fuel/air mixture gets compressed (and therefore heated) to the point that it will self-ignite. In other words, your gasoline/petrol motor becomes a diesel. (4) and maybe more. I don't claim to know everything. But I do know Wikipedia!, and, better yet, I know "The Secret Life of Machines"! This awesome program was one of my favorites growing up. That particular episode is "The Secret Life of the Internal Combustion Engine" and is worth watching in its entirety. But if you want to jump right to preignition, skip ahead to 15:44. I love the theme song. |
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| Author: | '67 Dart 270 [ Sun Aug 09, 2015 8:10 pm ] |
| Post subject: | hmm... |
Thanks Reed, I'll recheck the timing. Come to think of it, when I pulled the dizzy a few weeks back to check the cam/oil pump/dizzy gears, I assumed that I put it back correctly. It appeared that I put it back exactly as I took it out, but like a dufus I didn't take the time to check the timing. My DCR is 8:1 and I run 91 octane. I pulled a plug when I checked the gears, and I didn't see any carbon residues, but I can check again. It does make this noise most noticeably when I'm climbing a big hill. Today I was driving to Concord and it was 72 degrees at my house but in the 90's in the valley. I was going up a steep long hill in that heat when it was most noticeable. My temp gauge went up more than typical, not high, but moved about a 1/8 inch upward or so, it cooled back down on the downslope quickly. I'll report back on my findings. Brian |
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| Author: | '67 Dart 270 [ Sun Aug 09, 2015 8:30 pm ] |
| Post subject: | timing |
Timing is 10 degrees advanced, I did put it back exactly where it was... Will check for cracked manifold, Also, I'll check the AFR, see if I'm running lean. brian |
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| Author: | wjajr [ Mon Aug 10, 2015 6:06 am ] |
| Post subject: | |
Three thoughts that may or may not be applicable in order of seriousness: Without hearing your noise, I would suspect some small exhaust leak. If it were pre-ignition I don't think the noise would be as consistent due to air density changes with humidity and temperature. Pre ignition sound has more of a clattering rattling flavor to it, (think older diesel engine racket at idle) than a defined staccato sound, and can be easily varied with slight throttle changes when under load. Slight throttle changes quickly changes vacuum advance and A/F enrichment resulting in very different combustion chamber conditions. If you run the car and noise becomes louder over a few weeks, and comes on with less throttle input, that would point to an exhaust leak becoming larger. One way I have located exhaust leaks is by using a tube stuck in one ear, and passing its end closely around all of the possible exhaust leak locations while engine is idling. This isolates a local sound from all the clutter of engine white under hood noise. If there is a leak, it will come in load & clear. Two It would be helpful to know how much mechanical advance engine has. If it is over 30 degrees when all in, this could very well be a timing issue as well. As you know when under acceleration or climbing a hill vacuum advance due to lower manifold vacuum drops off a little to no advance depending on throttle position, and engine load. Mechanical advance is dependent on engine rpm starting just above idle rpm to all in around 2300 to 2600 rpm on most slants; your timing curve may very, but still is dependent on rpm. So what I driving at here is if this engine is making that noise at say 2000 rpm with throttle open enough to prevent any vacuum advance timing input, this may point to an exhaust leak. Three, and needs to be ruled out first. Quote: I did note a lot of pearlescent material in the oil though, seemed like a lot to me. There were also a couple of small metal bits here and there. I tore apart the filter and there wasn't much to speak of, just the pearly stuff in the oil.
This pearly stuff is concerning, where it's not collecting on the magnet it probably is bearing material, and probably from one of the rod barings.
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| Author: | '67 Dart 270 [ Mon Aug 10, 2015 7:58 am ] |
| Post subject: | timing |
I had set the timing on the last build to 10 advanced, and with a spring kit in the super six distributor, I was all in at before 3000 rpm, and not over 30 total mechanical. That may not be appropriate for this build though. Just now, I set the timing from 10 degrees advanced to just a few degrees advanced, so cranked it back about 8 degrees. It starts fine, and idles smoothly still, so I'll take it for a drive today and check it out. Brian |
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| Author: | '67 Dart 270 [ Mon Aug 10, 2015 8:01 am ] |
| Post subject: | bearings |
If it is (bad) pre-ignition, it might be hammering the bearings pretty hard and making that material, seems consistent. Let's see what the timing retardation does. b |
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| Author: | Sam Powell [ Mon Aug 10, 2015 2:08 pm ] |
| Post subject: | |
If retarding the timing makes it go away, then get an adjustable vacuum advance canister, and set it so vacuum advance is pulled out at lower vacuum reading. My guess though is vacuum leak. You can look for it by blowing smoke up the tail pipe, under pressure. Good shops have a tool for this. Sam |
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| Author: | sandy in BC [ Mon Aug 10, 2015 2:25 pm ] |
| Post subject: | |
Quote: blowing smoke up the tail pipe, under pressure.
..... this Maryland Technique evolved from living so close to the Federal Capitol......
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| Author: | '67 Dart 270 [ Mon Aug 10, 2015 4:25 pm ] |
| Post subject: | vacuum can |
I have an 11.OR can from a super six distributor, rebuilt for what that's worth. It seems to be working OK. Just out of curiosity, what is a good brand of adjustable vacuum pod that folks might recommend if I go that way? Brian |
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| Author: | Sam Powell [ Tue Aug 11, 2015 5:36 am ] |
| Post subject: | |
Some factory pods were adjustable. Crane used to sell one thst was. Don't worry about it unless retarding the base timimg helps with the noise. Sam |
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