The Ford Barn

Ole Don · 05-18-2021, 06:31 PM

If the person who rebuilt the engine failed to replace the top end bushings in the rods, it will give a light knock at idle. Some think the bushing is so small, it can be overlooked. It needs to be done right.

Hot Rod Reverend · 05-19-2021, 07:19 AM

this is all interesting - these knocks at idle, or otherwise, can be hard to diagnose unless you tear into the engine. And we all know that usually means at least removing a head for a look-see. My 292 runs like a cat on a hot tin roof, has excellent spark plug readings, and all the rest; yet I have a very light knock in #1 cylinder whenever the engine is cool. Above idle, you can never hear it. After a 5 minute warm-up it goes away completely. Reading all of this kind would lead me to believe that it may be a pin bushing for #1 piston's connecting rod... dunno. Not sure if it's worth it to tear into it for all of that - nothing has gotten worse over 2 years time but what do I know?

darrell · 05-19-2021, 08:10 AM

wouldnt touch it.

delco1946 · 05-19-2021, 10:02 AM

Thanks for all the ideas and questions. Since I was worried that it could be the sound of impending detonation/doom, I swung by my mechanic to listen.

They didn't seem to think it sound like anything, so at least I feel good that I likely have time to find it and fix it. I think part of it is that older folks' hearing is slightly diminished, and it didn't seem as loud to him, but to me its quite loud and driving me bonkers.

After watching him with a mechanics stethoscope, that gave me the idea to stick tubing to my ear and listen for the noise. I spent last night poking around I think I have found it - a particular spark plug boot, on the drivers side closest to the dash which would explain why its so loud in the cabin. When I push on the boot, the sound changes and/or goes away, and I could feel pulsing that matches the timing of the noise.

I have yet to change the wires since i've had the car and knowing what i know about it and the previous owners, i'm guessing the wires are at least 10 years old. This particular boot was once black/grey and is now whiteish so i'm guessing its at the end of its life.

I ordered new wires last night, so hopefully that fixes it and sorry for the wild goose chase.

Anteek29 · 05-19-2021, 02:36 PM

I am at a loss why pulsing could be felt through the boot...unless compression or exhaust leakage under or thru the spark plug?

delco1946 · 05-19-2021, 02:47 PM

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I think it’s from a arcing within the boot to the plug?

Daves55Sedan · 05-19-2021, 06:54 PM

In response to HRR's post and relative to his engine knock, This past January I noticed a knock in my 292 while it was cold, before the engine warmed up, but after the engine warmed up, the knock went away. I could even hear the knock sitting in the driver seat with engine idling and door closed.
A few days later we had a rare 50 degree day in January (Southern illinois). It sounded like it was coming from the driver side of the engine, so I popped the rocker arm cover off and grabbed each of the rocker arms as the engine idled to see if any were loose. I ended up tightening up #5 by 1/4 turn and #8 by 1/8 of a turn. Since then, I have never heard the noise again upon startup.

The stethoscope thing is a good idea. I suggest sticking the scope tube behind the engine and rest it on the trans bellhousing. If it sounds louder here than anywhere else, I would bet your Fordomatic flex-plate tabs have loosened up.

Back in 2001 (one year since the completion of my '55 Courier 223 I-block 6 rebuild), I noticed the engine running a little crappy. Within 10 minutes I noticed that #1 spark plug boot was cracked all the way down to the spark plug connector and spark was arcing to engine block ground. I couldn't believe it. One year old reproduction spark plug cables from the Chi-coms wouldn't hold up even for one year. I'm running repro spark plug cables on my Fairlane sedan that have been on there since 1984!!!

05-18-2021, 06:31 PM	#21
Ole Don Senior Member Join Date: May 2010 Location: St. Michael, Minnesota Posts: 1,713	Re: engine knocking 292 If the person who rebuilt the engine failed to replace the top end bushings in the rods, it will give a light knock at idle. Some think the bushing is so small, it can be overlooked. It needs to be done right.

05-19-2021, 07:19 AM	#22
Hot Rod Reverend Senior Member Join Date: May 2010 Location: Lancaster, CA Posts: 916	Re: engine knocking 292 this is all interesting - these knocks at idle, or otherwise, can be hard to diagnose unless you tear into the engine. And we all know that usually means at least removing a head for a look-see. My 292 runs like a cat on a hot tin roof, has excellent spark plug readings, and all the rest; yet I have a very light knock in #1 cylinder whenever the engine is cool. Above idle, you can never hear it. After a 5 minute warm-up it goes away completely. Reading all of this kind would lead me to believe that it may be a pin bushing for #1 piston's connecting rod... dunno. Not sure if it's worth it to tear into it for all of that - nothing has gotten worse over 2 years time but what do I know? __________________ Lancaster, California Visit hotrodreverend.com to view hundreds of pictures and videos of the build of the 1955 Ford Club Sedan!

05-19-2021, 08:10 AM	#23
darrell Senior Member Join Date: Dec 2010 Location: p.e.i. Posts: 1,060	Re: engine knocking 292 wouldnt touch it.

05-19-2021, 10:02 AM	#24
delco1946 Senior Member Join Date: Dec 2017 Location: Gladstone, OR Posts: 170	Re: engine knocking 292 Thanks for all the ideas and questions. Since I was worried that it could be the sound of impending detonation/doom, I swung by my mechanic to listen. They didn't seem to think it sound like anything, so at least I feel good that I likely have time to find it and fix it. I think part of it is that older folks' hearing is slightly diminished, and it didn't seem as loud to him, but to me its quite loud and driving me bonkers. After watching him with a mechanics stethoscope, that gave me the idea to stick tubing to my ear and listen for the noise. I spent last night poking around I think I have found it - a particular spark plug boot, on the drivers side closest to the dash which would explain why its so loud in the cabin. When I push on the boot, the sound changes and/or goes away, and I could feel pulsing that matches the timing of the noise. I have yet to change the wires since i've had the car and knowing what i know about it and the previous owners, i'm guessing the wires are at least 10 years old. This particular boot was once black/grey and is now whiteish so i'm guessing its at the end of its life. I ordered new wires last night, so hopefully that fixes it and sorry for the wild goose chase.

05-19-2021, 02:36 PM	#25
Anteek29 Senior Member Join Date: Dec 2014 Location: Santa Maria, CA Posts: 985	Re: engine knocking 292 I am at a loss why pulsing could be felt through the boot...unless compression or exhaust leakage under or thru the spark plug? __________________ Alan 1929 Special Coupe 1941 Pick-Up 1955 Victoria

05-19-2021, 02:47 PM	#26
delco1946 Senior Member Join Date: Dec 2017 Location: Gladstone, OR Posts: 170	Re: engine knocking 292 Sponsored Links (Register now to hide all advertisements) I think it’s from a arcing within the boot to the plug?

05-19-2021, 06:54 PM	#27
Daves55Sedan Senior Member Join Date: May 2010 Location: Granite City, Illinois Posts: 3,008	Re: engine knocking 292 In response to HRR's post and relative to his engine knock, This past January I noticed a knock in my 292 while it was cold, before the engine warmed up, but after the engine warmed up, the knock went away. I could even hear the knock sitting in the driver seat with engine idling and door closed. A few days later we had a rare 50 degree day in January (Southern illinois). It sounded like it was coming from the driver side of the engine, so I popped the rocker arm cover off and grabbed each of the rocker arms as the engine idled to see if any were loose. I ended up tightening up #5 by 1/4 turn and #8 by 1/8 of a turn. Since then, I have never heard the noise again upon startup. The stethoscope thing is a good idea. I suggest sticking the scope tube behind the engine and rest it on the trans bellhousing. If it sounds louder here than anywhere else, I would bet your Fordomatic flex-plate tabs have loosened up. Back in 2001 (one year since the completion of my '55 Courier 223 I-block 6 rebuild), I noticed the engine running a little crappy. Within 10 minutes I noticed that #1 spark plug boot was cracked all the way down to the spark plug connector and spark was arcing to engine block ground. I couldn't believe it. One year old reproduction spark plug cables from the Chi-coms wouldn't hold up even for one year. I'm running repro spark plug cables on my Fairlane sedan that have been on there since 1984!!!