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I have a new knocking noise on my 1986 f250 7.5 liter. I replaced the distributor cap and rotor and it started knocking. I put the old ones back on and it is still making the same noise. I double and Triple checked the firing order. I removed every belt. Any ideas??
I have a new knocking noise on my 1986 f250 7.5 liter. I replaced the distributor cap and rotor and it started knocking. I put the old ones back on and it is still making the same noise. I double and Triple checked the firing order. I removed every belt. Any ideas??
Maybe the rotor wasn't pushed on fully and is hitting the cap?
It's ticking or knocking? I can't watch the video on my limited internet connection. If it's ticking, I would wait till nighttime and start the engine and see if you see any sparks jumping around making the ticking noise. Follow the sparkplug wires looking for sparks. Spraying water on the wires may aggravated it and make it more noticeable.
I replaced the distributor cap and rotor and it started knocking.
Was any other work done besides the new cap and rotor?
A general consensus please: Does that sound too fast to be related to one cylinder, such as a rod knock?
I know you said you repeatedly checked the firing order, but how about this quick test. Disconnect one plug wire at a time and see if the problem gets better.
In your video, the noise sounds loudest at 0:10, when closest to the distributor. By 0:13, it seems more muffled with the air pump (?) between the distributor and camera.
Does it make the noise while cranking? If yes, try removing the rotor. You'll want to protect the coil by unplugging and grounding the distributor's center lead.
The noise sure seems like the rotor hitting the posts inside the cap. That would be a quick way to rule that out.
Wow, it almost sounds like one or both of the mechanical advance weights have become disconnected from their springs and are hitting the inside of the distributor.
Try this, take the cap off and give the rotor a little twist to check the mechanical advance. You should be able to turn the rotor a few degrees against the mechanical advance springs and then it should spring right back. If the rotor flops loosely back and fourth that's not right.
Wow, it almost sounds like one or both of the mechanical advance weights have become disconnected from their springs and are hitting the inside of the distributor.
Try this, take the cap off and give the rotor a little twist to check the mechanical advance. You should be able to turn the rotor a few degrees against the mechanical advance springs and then it should spring right back. If the rotor flops loosely back and fourth that's not right.
I like this idea, but I think the advance weights have mechanical stops to limit their travel. In other words, if the springs fail for whatever reason, they still won't travel out far enough to make contact.
sorry for being absent for a little while. I replaced plugs and wires and I still have a problem. Whatever it needed it anyway. I'll try the things that you have said. Should the rotor be almost tight? It has a little play when turning it back and fourth, maybe a degree or two. I'll check when I get home. Thanks for your input
The 'D' shaped rotor should fit tightly on the shaft.
The rotor should turn against spring tension of the centrifugal advance weights.
But.... It should snap back into place when released.
IF the spring retainer (that's really tricky to install) is missing from the the top of the distributor shaft (right underneath the rotor) then it would be easy for the mechanical advance "sleeve and plate assembly" to lift up when you pull the rotor.
The first thing I'd check is if the retainer is installed at the top of the distributor and that the mechanical advance shaft isn't free to lift up. If that shaft can lift up then the mechanical advance weights are very likely off their stops and rattling against the inside if the distributor housing.
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