Engine noises
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New User
Joined: Oct 2004
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Engine noises
1977 F100, 302 Motor.
Was driving, out of the blue, all of a sudden, tap tap tap tap tap tap in the motor. Faster I go, louder it is. I am sure you all have heard this classic noise before.
I checked my oil immediatley, oil was fine just down about 1/4 of a quart. Engine still running cool, never got hot. The only thing I have really noticed (before this happened) when I go over 55 mph, the motor starts to sounds like a deisel motor, then when I let off, quiets down
If I spun a bearing would the engine seize immed. not get hot? Or does it take a while of tapping then it will seize?
Oil pump going out? (my oil pressure gauge doesn't work)
What about water pump bearing?
What about rods?
I am not a mechanic just know bits and pieces so I don't know where to start. Thanks for any advice.
Was driving, out of the blue, all of a sudden, tap tap tap tap tap tap in the motor. Faster I go, louder it is. I am sure you all have heard this classic noise before.
I checked my oil immediatley, oil was fine just down about 1/4 of a quart. Engine still running cool, never got hot. The only thing I have really noticed (before this happened) when I go over 55 mph, the motor starts to sounds like a deisel motor, then when I let off, quiets down
If I spun a bearing would the engine seize immed. not get hot? Or does it take a while of tapping then it will seize?
Oil pump going out? (my oil pressure gauge doesn't work)
What about water pump bearing?
What about rods?
I am not a mechanic just know bits and pieces so I don't know where to start. Thanks for any advice.
Senior User
Joined: Jun 2004
Posts: 113
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I am not an expert either but I'll give my 2 cents. the deisel noise you heard was probably what most people call pinging. It is also called pre-detonation. What happens is your valves and pistons develop carbon deposits. These deposits get super hot and cause the gas to ignite before the spark plug fires. This is very bad for your pistons and valves. it can cause pitting. I have heard of extreme cases where pistons had holes in them. If I had to guess.(I'm no expert) I would look for a burned valve. Pingign can also be caused by high compression ratios with low octane gas.
Laughing Gas
Joined: Aug 2004
Posts: 1,249
Likes: 2
From: Rockport, WA
As you've realized by now, there are a lot of possiblities, and it's REALLY hard to diagnose a sound that we haven't heard. Time to check oil pressure, look at the oil, look the engine over, and take a ride with a real Mechanic who has a good ear. From here, the good folks on this forum can't tell a lifter "clicking" from an exhaust leak "ticking." All we can do is talk about possiblities.
BTW, I once had an International 304 get sick on me and make a really bad clicking. Turned out a lifter had collapsed enough to let a pushrod come out from under its rocker arm. It was sort of bouncing around, doing its own thing, but definitely not opening its valve any more. The Cornbinder ran on seven cylinders, but it wasn't very happy...
BTW, I once had an International 304 get sick on me and make a really bad clicking. Turned out a lifter had collapsed enough to let a pushrod come out from under its rocker arm. It was sort of bouncing around, doing its own thing, but definitely not opening its valve any more. The Cornbinder ran on seven cylinders, but it wasn't very happy...
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Freshman User
Joined: Mar 2003
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I believe 1977 was one of the years for the small block with rail rockers. You might want to narrow down where the noise is coming from. The rail rockers were known for wearing down the valve stem to the point that the rails on the rockers would contact the spring retainer. First ticking then....
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Laughing Gas
Joined: Aug 2004
Posts: 1,249
Likes: 2
From: Rockport, WA
Uh oh! You do NOT want to lose a valve retainer. It messes up your whole day when the valve goes through the piston. Time to get someone to lay experienced eyes and ears on the problem. Always good to deal with it while it's still a SMALL problem. 
Freshman User
Joined: Aug 2002
Posts: 28
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From: Lake Havasu City, Arizona
Does your noise reduce or go away at idle? Either way, rule out the belts and bolt-ons first. I got stung on this twice. One was a bad alternator, and the other was a split p/s belt. Both problems showed no sign at idle, only at highway speeds.
Moderator
Joined: Dec 2001
Posts: 22,436
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From: Louisville,Ky.
77 has pedestal mounted rockers, not rail mounted. Each rocker arm is bolted down to an aluminum pedestal that holds the proper preload on the lifters. It sounds like you possibly have a collapsed lifter. I would definately hook up a mechanical oil presure gauge to check actual pressure before anything else.
Freshman User
Joined: May 2004
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Check the easy things first. If you have a vacuum advance distributor, pull the vacuum line off it and drive it up past the speed where you start hearing the noise. NO cost or replacements involved in this diagnosis. I'm having the same problem with my 400 and this identified the issue. Timing needed retarding.
If this stops the noise, retard your timing and address the next question. "why did the timing change?"
If this stops the noise, retard your timing and address the next question. "why did the timing change?"