knock on start up
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Junior User
Joined: Sep 2009
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knock on start up
i got a 96 ford bronco with an awesome 302. but when i try to turn her on after a little bit of sitting she makes this awful knocking noise just on start up. i no its not an intewrnal knock or anything like the valves or pistons. its seems to be an external knock. but its only on startup. and its not a grind or anyhting so its not the starter but than again i geuss it could be iono. any idears?
Lead Driver
Joined: Sep 2002
Posts: 9,182
Likes: 12
From: Gateway to the West
Are you absolutely certain its not lifter click? What oil filter are you running? 302's and 351's with anything other than a Motorcraft FL1-A or the Purolator equivalent (Purolator makes the FL1-A for Motorcraft) will be starved at start-up with any other filter. Its a valving issue. That and a little Lucas Oil conditioner should quiet things down.
Of course if you are certain that the noise is external to the engine, then there are a host of things that might be loose in the engine bay but since it only happens when the truck is stone cold, I'd be looking at exhaust components like catalytic converter heat shields and the like. These items would not necessarily rattle at start-up with the truck warm/hot because heat expansion could cause them to expand and therefore not rattle.
Of course if you are certain that the noise is external to the engine, then there are a host of things that might be loose in the engine bay but since it only happens when the truck is stone cold, I'd be looking at exhaust components like catalytic converter heat shields and the like. These items would not necessarily rattle at start-up with the truck warm/hot because heat expansion could cause them to expand and therefore not rattle.
Cross-Country
Joined: Feb 2004
Posts: 94
Likes: 8
From: Lincoln, NE
Not sure if my old issue is same as yours...
I have 2001 Ranger with 4.0, and it would do that if it sat for a few days between starts. Only one or two quick knocks right at start. I really couldn't tell if it was internal or not, so I mentioned it to my trusted mechanic who was at Ford Dealer for 15 years before opening his own garage. He recommended going from the 5W30 to 5W20. He said the newer OHC 4.0 engines would be just fine to run it, but not the older OHV 4.0's.
So at last oil change, I switched to 5W20, and I have had no startup knock in the 2 months since the oil change. And it sat 10 days between starts at the longest interval.
If you're positive the knock is not internal, this won't help, but thought I'd mention it in case anyone else is having similar knock.
I have 2001 Ranger with 4.0, and it would do that if it sat for a few days between starts. Only one or two quick knocks right at start. I really couldn't tell if it was internal or not, so I mentioned it to my trusted mechanic who was at Ford Dealer for 15 years before opening his own garage. He recommended going from the 5W30 to 5W20. He said the newer OHC 4.0 engines would be just fine to run it, but not the older OHV 4.0's.
So at last oil change, I switched to 5W20, and I have had no startup knock in the 2 months since the oil change. And it sat 10 days between starts at the longest interval.
If you're positive the knock is not internal, this won't help, but thought I'd mention it in case anyone else is having similar knock.
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