Cold start knock 4.6L
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Freshman User
Joined: Jun 2006
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Cold start knock 4.6L
1997 F150 2wd 4.6L v8 with A/T with 235k miles. Idles and drives perfectly except for this issue. Exhaust is clear even on start-up.
There are no codes.
I park on a slight hill in my driveway. This morning when I started it, I could hear a distinct knock. I let it roll down the hill in neutral. When the vehicle was level at the bottom, it still knocked for a couple seconds. When I gave light pressure to the accelerator, it knocked a few more times as I drove slowly down the road, but it was gone in 100 yards. It did the exact same thing 2 weeks ago.
I changed the oil [10w-30 synthetic] and filter [Wix] about 10 days ago. When it made the noise 2 weeks ago, it had synthetic 5W-30 with about 5500 miles on it. Oil level is OK. Changed the fuel filter and spark plugs 4 days ago. Have driven about 200 miles since those things were done.
I have read of the 5.4 liter slap, but nothing about the 4.6. Anyone have any ideas ?
There are no codes.
I park on a slight hill in my driveway. This morning when I started it, I could hear a distinct knock. I let it roll down the hill in neutral. When the vehicle was level at the bottom, it still knocked for a couple seconds. When I gave light pressure to the accelerator, it knocked a few more times as I drove slowly down the road, but it was gone in 100 yards. It did the exact same thing 2 weeks ago.
I changed the oil [10w-30 synthetic] and filter [Wix] about 10 days ago. When it made the noise 2 weeks ago, it had synthetic 5W-30 with about 5500 miles on it. Oil level is OK. Changed the fuel filter and spark plugs 4 days ago. Have driven about 200 miles since those things were done.
I have read of the 5.4 liter slap, but nothing about the 4.6. Anyone have any ideas ?
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
What brand oil filter did you use?
It's a mistake to use heavier oil.
It does not get around fast enough on cold starts.
Some filter designs drain back.
Use the MC 820s filter.
If this does not clear the knock from lack of inital oil pressure, there is something else going on.
Good luck.
It's a mistake to use heavier oil.
It does not get around fast enough on cold starts.
Some filter designs drain back.
Use the MC 820s filter.
If this does not clear the knock from lack of inital oil pressure, there is something else going on.
Good luck.
Thread Starter
|
Freshman User
Joined: Jun 2006
Posts: 31
Likes: 0
What brand oil filter did you use?
It's a mistake to use heavier oil.
It does not get around fast enough on cold starts.
Some filter designs drain back.
Use the MC 820s filter.
If this does not clear the knock from lack of inital oil pressure, there is something else going on.
Good luck.
It's a mistake to use heavier oil.
It does not get around fast enough on cold starts.
Some filter designs drain back.
Use the MC 820s filter.
If this does not clear the knock from lack of inital oil pressure, there is something else going on.
Good luck.
"I changed the oil [10w-30 synthetic] and filter [Wix] about 10 days ago. When it made the noise 2 weeks ago, it had synthetic 5W-30 with about 5500 miles on it. Oil level is OK."
It had a NAPA Gold filter 2 weeks ago, and a premium Wix filter this time. It isn't the oil filter, either.
Senior User
Joined: Sep 2004
Posts: 218
Likes: 0
From: Douglasville,GA
It is not the oil. As stated in the original post:
"I changed the oil [10w-30 synthetic] and filter [Wix] about 10 days ago. When it made the noise 2 weeks ago, it had synthetic 5W-30 with about 5500 miles on it. Oil level is OK."
It had a NAPA Gold filter 2 weeks ago, and a premium Wix filter this time. It isn't the oil filter, either.
"I changed the oil [10w-30 synthetic] and filter [Wix] about 10 days ago. When it made the noise 2 weeks ago, it had synthetic 5W-30 with about 5500 miles on it. Oil level is OK."
It had a NAPA Gold filter 2 weeks ago, and a premium Wix filter this time. It isn't the oil filter, either.
Junior User
Joined: Feb 2005
Posts: 99
Likes: 0
From what I understand, there is no lifters in the 4.6l. I have the same issue with the cold start knock. Im 99.9% sure its an exaust manifold leak on the drivers side. Once the motor heats up it seals the leak, thus ending the terrible noise of what you may think is an engine knock. Before I thought it was lifters etc, I put in sea foam, diesel fuel in crank case rtc to clean the engine, nothing worked. Exaust manifold leaks make the same knock, if your lucky thats what the problem is. Oh and by the way mine was intermittent like yours aswell. When you think its gone, it comes back.
Laughing Gas
Joined: Oct 2003
Posts: 967
Likes: 0
From: DC
Edit: Sorry, it's 5w-30 vice 5w-20 for '97.
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Freshman User
Joined: Jan 2010
Posts: 36
Likes: 0
It is not the oil. As stated in the original post:
"I changed the oil [10w-30 synthetic] and filter [Wix] about 10 days ago. When it made the noise 2 weeks ago, it had synthetic 5W-30 with about 5500 miles on it. Oil level is OK."
It had a NAPA Gold filter 2 weeks ago, and a premium Wix filter this time. It isn't the oil filter, either.
"I changed the oil [10w-30 synthetic] and filter [Wix] about 10 days ago. When it made the noise 2 weeks ago, it had synthetic 5W-30 with about 5500 miles on it. Oil level is OK."
It had a NAPA Gold filter 2 weeks ago, and a premium Wix filter this time. It isn't the oil filter, either.
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