Engine Problem
Thread Starter
Melting Slicks<br><img src="/forums/images/ranks/3k-4k.gif" border="0">
Joined: Mar 2008
Posts: 3,272
Likes: 2,218
From: Colorado Springs Colorado
2024 C2 of the Year Finalist - Modified
2023 C2 of the Year Finalist - Unmodified
Engine Problem
'66 L79 engine pretty much stock with a QF carb and Pertronix.
About 6 weeks ago the engine was running great and I did the annual oil change (Rotella) and when I started up the engine to back it off the ramps, I heard a metal on metal scraping sound. I looked in the engine bay where it was clearly coming from but couldn't pinpoint the source. I moved it back into its normal spot in my garage but I didn't have time to pursue it right away.
Over the past couple weeks here is what I've done to locate the problem which seems to be coming from the front passenger side of the engine, without success.
- removed the 2 belts, fan and water pump pulley to eliminate them spinning. Still had the noise
- removed the right side valve cover to check for a loose rocker; all were tight
- removed the fuel pump, plate and rod; rod and pump are both good
This past weekend, I put the fuel pump back on and tried to start it (fuel is getting to carb), but it now won't start (the last time I started it last week for a minute, it ran rough).
I'm now thinking I may have a problem with the timing chain.
I'd like to have your thoughts and ideas on this as well as ask if I can pull off the timing cover without pulling the engine.
About 6 weeks ago the engine was running great and I did the annual oil change (Rotella) and when I started up the engine to back it off the ramps, I heard a metal on metal scraping sound. I looked in the engine bay where it was clearly coming from but couldn't pinpoint the source. I moved it back into its normal spot in my garage but I didn't have time to pursue it right away.
Over the past couple weeks here is what I've done to locate the problem which seems to be coming from the front passenger side of the engine, without success.
- removed the 2 belts, fan and water pump pulley to eliminate them spinning. Still had the noise
- removed the right side valve cover to check for a loose rocker; all were tight
- removed the fuel pump, plate and rod; rod and pump are both good
This past weekend, I put the fuel pump back on and tried to start it (fuel is getting to carb), but it now won't start (the last time I started it last week for a minute, it ran rough).
I'm now thinking I may have a problem with the timing chain.
I'd like to have your thoughts and ideas on this as well as ask if I can pull off the timing cover without pulling the engine.
Drifting
Joined: Jan 2013
Posts: 1,772
Likes: 196
From: Asheville NC
You're going about it right
Hi Warren,
I would do the same things your doing. Try to pinpoint the noise by isolating one component at a time - simple to difficult.
It would make sense that a timing chain could be a problem as the sudden stop of the engine when you shut it off could have shucked some of the cam gear.
You could also pull the rocker covers and inspect the rocker arm movement
Phil
I would do the same things your doing. Try to pinpoint the noise by isolating one component at a time - simple to difficult.
It would make sense that a timing chain could be a problem as the sudden stop of the engine when you shut it off could have shucked some of the cam gear.
You could also pull the rocker covers and inspect the rocker arm movement
Phil
Team Owner
Joined: Mar 2002
Posts: 44,653
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From: Huntsville AL
Yes but you need to pull the oil pan to do it right. Before doing that I would check the timing to make sure its the timing chain. I don't think the noise would be coming from the chain.
Thread Starter
Melting Slicks<br><img src="/forums/images/ranks/3k-4k.gif" border="0">
Joined: Mar 2008
Posts: 3,272
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From: Colorado Springs Colorado
2024 C2 of the Year Finalist - Modified
2023 C2 of the Year Finalist - Unmodified
Team Owner
Joined: Aug 2007
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Army
A mechanic's stethoscope should be in every toolbox or a short length of rubber garden hose to isolate the sound...
My sister's '71 Pontiac 350 LeMans had a timing chain jump a tooth mysteriously years ago. She pulled up in our Dad's driveway, shut the car down and it wouldn't start back up. Brother and I swapped it out the next day...
My sister's '71 Pontiac 350 LeMans had a timing chain jump a tooth mysteriously years ago. She pulled up in our Dad's driveway, shut the car down and it wouldn't start back up. Brother and I swapped it out the next day...
Pro
Joined: Apr 2008
Posts: 502
Likes: 37
From: Pine Barrens New Jersey
If I thought it was the timing chain or valve train causing the noise the first thing I would do is pull the distributor cap and check for rotation and rotor alignment. Then I would pull the valve covers to check rocker movement.
Melting Slicks
Joined: Jan 2007
Posts: 2,842
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From: Pasco Florida
My 1st guess is that while changing the oil/filter, you bumped the flywheel cover and it is scraping on the flywheel? Very common problem with the original design covers.
Also, it's possible that the scraping noise is not related to the way the engine started running after a while.
Also, it's possible that the scraping noise is not related to the way the engine started running after a while.
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Team Owner
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Army
My 1st guess is that while changing the oil/filter, you bumped the flywheel cover and it is scraping on the flywheel? Very common problem with the original design covers.
Also, it's possible that the scraping noise is not related to the way the engine started running after a while.
Also, it's possible that the scraping noise is not related to the way the engine started running after a while.
Burning Brakes
Joined: Jul 2014
Posts: 1,071
Likes: 480
From: Colorado Springs CO
If your final diagnosis leads to pulling the timing cover you may find a nylon cam timing gear decided to fail. You stated having a 67 replacement block, not sure when the nylon gears started appearing and when they were discontinued. I am hoping for something else simple, like the flywheel cover already mentioned.
Team Owner
Joined: Mar 2003
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From: Greenville, Indiana
Before you go to all the trouble to pull the timing cover, roll the engine to TDC on #6 cyl. Both rockers on #1 cyl should be slightly depressed about an equal amount. Exhaust almost closed and intake starting to open. If that's what you see, the timing chain is not your problem.
Team Owner
Joined: Aug 2007
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Army
Before you go to all the trouble to pull the timing cover, roll the engine to TDC on #6 cyl. Both rockers on #1 cyl should be slightly depressed about an equal amount. Exhaust almost closed and intake starting to open. If that's what you see, the timing chain is not your problem.
Thread Starter
Melting Slicks<br><img src="/forums/images/ranks/3k-4k.gif" border="0">
Joined: Mar 2008
Posts: 3,272
Likes: 2,218
From: Colorado Springs Colorado
2024 C2 of the Year Finalist - Modified
2023 C2 of the Year Finalist - Unmodified
A mechanic's stethoscope should be in every toolbox or a short length of rubber garden hose to isolate the sound...
My sister's '71 Pontiac 350 LeMans had a timing chain jump a tooth mysteriously years ago. She pulled up in our Dad's driveway, shut the car down and it wouldn't start back up. Brother and I swapped it out the next day...
My sister's '71 Pontiac 350 LeMans had a timing chain jump a tooth mysteriously years ago. She pulled up in our Dad's driveway, shut the car down and it wouldn't start back up. Brother and I swapped it out the next day...
Thread Starter
Melting Slicks<br><img src="/forums/images/ranks/3k-4k.gif" border="0">
Joined: Mar 2008
Posts: 3,272
Likes: 2,218
From: Colorado Springs Colorado
2024 C2 of the Year Finalist - Modified
2023 C2 of the Year Finalist - Unmodified
My 1st guess is that while changing the oil/filter, you bumped the flywheel cover and it is scraping on the flywheel? Very common problem with the original design covers.
Also, it's possible that the scraping noise is not related to the way the engine started running after a while.
Also, it's possible that the scraping noise is not related to the way the engine started running after a while.
Thread Starter
Melting Slicks<br><img src="/forums/images/ranks/3k-4k.gif" border="0">
Joined: Mar 2008
Posts: 3,272
Likes: 2,218
From: Colorado Springs Colorado
2024 C2 of the Year Finalist - Modified
2023 C2 of the Year Finalist - Unmodified
If your final diagnosis leads to pulling the timing cover you may find a nylon cam timing gear decided to fail. You stated having a 67 replacement block, not sure when the nylon gears started appearing and when they were discontinued. I am hoping for something else simple, like the flywheel cover already mentioned.
Race Director
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Thread Starter
Melting Slicks<br><img src="/forums/images/ranks/3k-4k.gif" border="0">
Joined: Mar 2008
Posts: 3,272
Likes: 2,218
From: Colorado Springs Colorado
2024 C2 of the Year Finalist - Modified
2023 C2 of the Year Finalist - Unmodified
Before you go to all the trouble to pull the timing cover, roll the engine to TDC on #6 cyl. Both rockers on #1 cyl should be slightly depressed about an equal amount. Exhaust almost closed and intake starting to open. If that's what you see, the timing chain is not your problem.
Le Mans Master
Joined: Sep 2008
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From: Lake Minnetonka, Mn
2018 C1 of Year Finalist
If your final diagnosis leads to pulling the timing cover you may find a nylon cam timing gear decided to fail. You stated having a 67 replacement block, not sure when the nylon gears started appearing and when they were discontinued. I am hoping for something else simple, like the flywheel cover already mentioned.
Last edited by Dan Hampton; May 29, 2018 at 09:57 PM.
Thread Starter
Melting Slicks<br><img src="/forums/images/ranks/3k-4k.gif" border="0">
Joined: Mar 2008
Posts: 3,272
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From: Colorado Springs Colorado
2024 C2 of the Year Finalist - Modified
2023 C2 of the Year Finalist - Unmodified
BTW, even though I will check the flywheel cover, I do not think that is the problem as the noise is clearly coming from the front of the engine.