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  #1 (permalink)  
Old 06-09-2024, 03:10 PM
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Default Weird engine trouble

So we took the wife out for a ride. Stopped for an hour, and just as we were leaving the engine started ticking/tapping. Sounded like an exhaust leak, so we drove home easy…

Background, 427 stroker, Big hydro cam, 850 dp, trickflow r manifold. Just recently discovered a bad ground at the battery, and fixed it. Car was cutting out periodically, lug was actually cracked in half…Msd 6al box. Have a spare, swapped it out and no change.

Got home and started troubleshooting, discovered that the tick/tap stopped when plug wire 7 was pulled off the distributor. Tried switching pugs and wires no change. There does seem to be a periodic arc at the plug. But insulating the heck out of it by wrapping it in a sliced hose didnt help.

Reading the internet i am worried i have a bad rod bearing? Seems strange that it would cause arcing at the plug?

I drained the oil, and see nothing in it…havent cut open the filter.

Any ideas?
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Steve H
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Old 06-09-2024, 04:22 PM
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Pull the pan and stop guessing.
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Old 06-09-2024, 05:07 PM
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Big hydro cam
I’d check under valve cover
Maybe lifter makes noise only when cylinder pressure is up
Do the easy stuff first
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Old 06-09-2024, 05:21 PM
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Default Did that

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Originally Posted by sunman View Post
Big hydro cam
I’d check under valve cover
Maybe lifter makes noise only when cylinder pressure is up
Do the easy stuff first
Originally thought lifter or exh leak, pulling the plug wire and stopping the noise initially was a relief, but when i couldn’t cure it with swapping plugs/wires i started worrying. Swapped boxes, distributors, pulled the valve cover, ran it (big oily mess)…. I am seeing arcing at the plug, but even sliding a hose over the boot did nothing…
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Old 06-09-2024, 05:24 PM
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Default Yup

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Originally Posted by eschaider View Post
Pull the pan and stop guessing.
Im on the ground no lift…did replace the pan once with help back in commiefornistan where i had help…dont have any now here in SC. That big canton pan is a bit of a ***** to get back on…
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Old 06-09-2024, 05:29 PM
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Default Yup

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Originally Posted by eschaider View Post
Pull the pan and stop guessing.
Im on the ground no lift…did replace the pan once with help back in commiefornistan where i had help…dont have any now here in SC. That big canton pan is a bit of a ***** to get back on…
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Old 06-09-2024, 05:31 PM
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Quote:
Originally Posted by tortuga View Post
Originally thought lifter or exh leak, pulling the plug wire and stopping the noise initially was a relief, but when i couldn’t cure it with swapping plugs/wires i started worrying. Swapped boxes, distributors, pulled the valve cover, ran it (big oily mess)…. I am seeing arcing at the plug, but even sliding a hose over the boot did nothing
Can we elaborate more on this?
You said you changed the plug AND the lead, and this still happens?
Is the sound a "sparking noise" or a "mechanical knock"?
Gary
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Old 06-09-2024, 07:18 PM
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Check your engine grounds and battery grounds.
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Old 06-10-2024, 03:05 AM
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Default Grounds

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Check your engine grounds and battery grounds.
Blas
I did just fix the battery ground. The engine ground as well.
Its just crazy how its only on one cylinder. Swapped plugs and wires?
Absolutely goes away with the #7 wire pulled at the distributor.
Oil is clean.
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Old 06-10-2024, 03:33 AM
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I'm not big on coincidences, so when a new problem arises right after I've done work on a car, I suspect I unknowingly did something while doing the previous work. And electricity takes the path of least resistance, so the arcing tells me there is too much resistance where the electricity is supposed to be going. If it were me I'd start by adding some temporary jumper cables to know the engine and ignition are properly grounded to see if that caused the arcing to stop. If so, I'd start looking for the bad connection(s).
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Old 06-10-2024, 04:36 AM
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Default Agree

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I'm not big on coincidences, so when a new problem arises right after I've done work on a car, I suspect I unknowingly did something while doing the previous work. And electricity takes the path of least resistance, so the arcing tells me there is too much resistance where the electricity is supposed to be going. If it were me I'd start by adding some temporary jumper cables to know the engine and ignition are properly grounded to see if that caused the arcing to stop. If so, I'd start looking for the bad connection(s).
Its just too weird that after fixing the battery ground in the trunk that i now have a weird electrical issue at the engine. Find a bad bearing very hard to believe…why would that cause a plug to arc.

Why just this one plug? All one cylinder head? Was thinking maybe ill run a ground wire directly from the cylinder head? Think there are tapped 7/16-14 holes i could bolt a cable to.

For the life of me i just dont understand how the header could be more grounded than the engine. The engine ground looks and feels good, but maybe the next step is to remove it and clean it good…
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Old 06-10-2024, 04:51 AM
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You don't have to use a full size battery jumper cable to test things. A long 12 gauge wire with alligator clips will do.
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Old 06-10-2024, 05:50 AM
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Did you check for a broken valve spring?
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Old 06-10-2024, 08:13 AM
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A mechanical "ticking, tapping sound" where there was none previously does not have an electrical origin; it has a mechanical origin. You can check all the various it isn't that bad sorts of non-mechanical origins possible. When you are all done, the odds are your mechanical "ticking, tapping sound" will have a mechanical origin.
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Old 06-10-2024, 08:32 AM
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I had a 65 t bird come into my shop 2 weeks ago with the same sound your describing and went away when plug wire disconnected, dropped the pan removed number 5 rod cap and bearing was gone didn't see anything bad in the oil. I hope I'm wrong but I have seen and heard this problem before.
BTW oil pressure was good.

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Old 06-10-2024, 03:23 PM
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My $0.02.
Joey.S brought the potential of a rod bearing. Let's follow that.
If pulling a plug wire eliminated the ignition (kaboom) in #7, perhaps that stopped the rod from pushing down on the crank journal - the tick. Now without the ignition in the #7 cylinder the crank is pulling the rod rather than the normal of having the piston push on the rod.
Hope this makes sense, sorta does to me. Otherwise just ignore my WAG.
I'd look at a lot before pulling the pan, yup a PITA with the SPF/Canton combination. Been there done that, I didn't like it either.
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Old 06-10-2024, 03:33 PM
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Perhaps one of those tiny cameras would allow you to take a peek without dropping the pan.
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Old 06-10-2024, 06:39 PM
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Tommy, exc. idea, we had the same type issue, bought Steve's (Back in Black) West Coast Cobra, pulled the dip stick (Nothing but the top of it ) Brent took his camera though the drain plug, to see if the rest of it was in the oil pan, thankfully it was not there That camera saved us pulling the pan. Cheers Tom.
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Old 06-10-2024, 09:09 PM
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Unless the tiny camera has a way to remove the rod cap you will not be able to inspect the rod bearing or the crank journal.
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Old 06-10-2024, 09:27 PM
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Quote:
Originally Posted by tortuga View Post
Its just too weird that after fixing the battery ground in the trunk that i now have a weird electrical issue at the engine. Find a bad bearing very hard to believe…why would that cause a plug to arc.

Why just this one plug? All one cylinder head? Was thinking maybe ill run a ground wire directly from the cylinder head? Think there are tapped 7/16-14 holes i could bolt a cable to.

For the life of me i just dont understand how the header could be more grounded than the engine. The engine ground looks and feels good, but maybe the next step is to remove it and clean it good…
Do you actually SEE this spark jumping?

How about a video? That would help other eyes for diagnosis.

A suspect bad rod bearing AND a sparking issue DOES NOT HAPPEN AT THE SAME TIME.
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Last edited by Gaz64; 06-10-2024 at 09:30 PM..
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