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Discussion Starter · #1 ·
How would you describe the sound of "knocking?" I did the ignition upgrade a few months ago and the other day I noticed what I think might be knock. It's an intermittent (note: not constant but on-off-on by the second and not any rhythm) "pinging" like a light rap of a screwdriver on the fender sound. It's very light--you can't hear it in the cab. You can only hear it when you're outside and I *think* it's only on teh driver's side.

So....I reduced my timing from about 13.5 to 11 and it's still there...but maybe it's something else? Any definitive tests to know for sure? It runs very well and I can't tell anything's wrong by driving it but I'd like to know for sure. I don't know why it would have changed, which makes it weird. I am using a heavier oil because I've had to do some towing lately but I don't know if that would make a difference.

As a positive note, my buddy and I went hunting today in the FSB. It was hillarious--he'd point to some really, really steep and gnarly roads and say "there's no way it can make it up that." Up we'd go, over and over, up things I didn't even think we'd make and I never even had to put it in 4x4. These things are frickin' tanks!


Thanks!

edit: Is knock potentially destructive? I think I remember reading that you can blow your seals or something?
 

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do you think you have a rod knock (bad) or a ping(engine detonation)? you can use a piece of wood dowl as a listening device to try and narrow down where the noise is eminating from.
 

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Discussion Starter · #4 ·
do you think you have a rod knock (bad) or a ping(engine detonation)? you can use a piece of wood dowl as a listening device to try and narrow down where the noise is eminating from.
Definitely more of a "ping" than a "knock." I'll try the wooden dowel and see if it helps locate it, I guess. Any other tricks?
 

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Are you sure it's not some kind of exhaust leak or loose bolt/clamp/exhaust pipe hitting against something and causing a kind of "ping" or vibration? Especially if you hear it more on one side than another I'd tend to thing it could be something silly. I always like to think the problem is something silly anyways because those problems cost a lot less $$ to fix ;). Anyways I know my F150 makes a cacophony of noises mostly because most of the exhaust hangers have rotted off and I really haven't the time to weld 'em back together :toothless.
 

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Discussion Starter · #7 ·
Are you sure it's not some kind of exhaust leak or loose bolt/clamp/exhaust pipe hitting against something and causing a kind of "ping" or vibration? Especially if you hear it more on one side than another I'd tend to thing it could be something silly. I always like to think the problem is something silly anyways because those problems cost a lot less $$ to fix ;). Anyways I know my F150 makes a cacophony of noises mostly because most of the exhaust hangers have rotted off and I really haven't the time to weld 'em back together :toothless.
Hmmmm...great call. Tell me this: When you have detonation problems, is it rhythmic or random? Anyone? Mine is not rhythmic, meaning it doesn't sound like it's happening on every single detonation or what have you.
 

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Discussion Starter · #9 ·
does it sound like a little man with a hammer trying to get out?
If my "little man" you mean 2 inches tall with a doll-sized hammer, yes.

Given my very limited understanding of detonation, it just seems weird to me that it comes in random spurts and not with the rhythm of the engine, you know?
 

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Try to find my posts with Expensive engine noise in them. There's a couple of vids there where you can hear my fried rings and bad rod bearing on #8 cylinder.............
 

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Discussion Starter · #11 ·
Try to find my posts with Expensive engine noise in them. There's a couple of vids there where you can hear my fried rings and bad rod bearing on #8 cylinder.............
Thanks for posting that, Ricky, but it's not NEARLY as loud nor as constant. It just goes in spurts and is waaaay more subltle.
 

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Have you checked to see if the noise is coming from your bell housing? Cracked flexplates can make strange noises like little rod knocks and such.
 

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Boy, a thread describing engine noises and their causes would be fun, if everyone agreed on the same definition!!! Here's mine along with a few tips to 'cipher them.

"knock" is loud and constant, and you can hear it in a car that goes by you or around the track. Sounds like a diesel engine, as the bottom of the piston hits the crankshaft. A bent rod or bad bearing is usually the problem, but may be a cracked flexplate/ flyhweel or a bolt backed out.

"tap" is softer but still loud enough to hear a few feet away. Something in the valves is not working, such as a lifter.

"tick" is about the same as a "tap" but is caused by an exhaust leak. A cracked exh manifold or more often a leaky header. This often goes away after the engine warms up.

"ping" is what I describe as "chatter" or "dieseling" due to detonation or pre-ignition of the fuel.You might notice this while accelerating, towing up a hill, or at a certain speed/ rpm. While this is often on and off, it's not good for your engine. Timing can affect this symptom as well as the fuel octane, or even water in the fuel.

It's hard to really hear the pinging while driving if you have big mud tires that growl, a loud exhaust or the stereo up, but you might feel a little hesitation.

The other static sounds can be isolated with a dowel, rod or rubber hose by placeing one end on the motor and the other to your ear. BEWARE OF MOVING PARTS!!! You'll be amazed at what you can hear with this technique, and placing the hearing aid on different areas of the motor like each valve cover, the exhaust manifolds, and underneath at the tranny bellhousing when checking a rod knock. JSM84
 

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Discussion Starter · #14 ·
Boy, a thread describing engine noises and their causes would be fun, if everyone agreed on the same definition!!! Here's mine along with a few tips to 'cipher them.

"knock" is loud and constant, and you can hear it in a car that goes by you or around the track. Sounds like a diesel engine, as the bottom of the piston hits the crankshaft. A bent rod or bad bearing is usually the problem, but may be a cracked flexplate/ flyhweel or a bolt backed out.

"tap" is softer but still loud enough to hear a few feet away. Something in the valves is not working, such as a lifter.

"tick" is about the same as a "tap" but is caused by an exhaust leak. A cracked exh manifold or more often a leaky header. This often goes away after the engine warms up.

"ping" is what I describe as "chatter" or "dieseling" due to detonation or pre-ignition of the fuel.You might notice this while accelerating, towing up a hill, or at a certain speed/ rpm. While this is often on and off, it's not good for your engine. Timing can affect this symptom as well as the fuel octane, or even water in the fuel.

It's hard to really hear the pinging while driving if you have big mud tires that growl, a loud exhaust or the stereo up, but you might feel a little hesitation.

The other static sounds can be isolated with a dowel, rod or rubber hose by placeing one end on the motor and the other to your ear. BEWARE OF MOVING PARTS!!! You'll be amazed at what you can hear with this technique, and placing the hearing aid on different areas of the motor like each valve cover, the exhaust manifolds, and underneath at the tranny bellhousing when checking a rod knock. JSM84

This is VERY helpful, THANKS! It's definitely not a rod or tap or knock. I never thought about a leaky header so I'm going to check that out. No water in the fuel but I think timing could be the culprit, even though I've already reduced it. Let me check out the headers and get back after that.
 

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Discussion Starter · #15 ·
Update:

So I had some time today to dick around the rig. First off, I tightened down the headers but there was only one bolt loose and it wasn't very loose at all. So I moved on...I checked my timing and it was still at 11*, where I left it last time after trying to reduce it from 13.5. In order to see if it was a timing issue, I removed the SPOUT and reduced timing down to 6*. The sound was still there, so I got on the creeper to try and locate the exact source. With a severed piece of garden hose, I did my best to try and locate the source but wasn't very successful. Strangely enough, it's clearest when my head was directly under the oil pan. I also tried using a longer piece of tube and placed it against different parts of the engine while on my mini step ladder and simply couldn't pin point it at any part of the engine. Back, forwards, up, down, on the valve covers or at the block, I couldn't hear any difference. Other than being directly under the rig, the loudest place to hear it outside of the truck is crouching directly under the driver door.

At this point, I'm at a loss. I brought the timing back up to 13.5 and it didn't seem to make a difference in intensity or anything, so I'm going to keep it there. I just don't know what else it could be, save an exhaust leak (it really doesn't sound like this) or a loose something-or-other.

The only other variable is the fact that I went to 15w-40 on my last oil change because I was going to be towing a bunch of stuff. I'm not sure how that could make a difference.

My next step is to maybe Seafoam via the vacuum tube and a quick can to the crankcase right before an oil change just to free up any gunk and maybe alleviate the possibility of a lifter or something. :banghead
 

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Discussion Starter · #17 ·
Did we ask what your oil pressure is yet?..........
Nope but it's very strong. When I bought it in May I had a hydraulic compression test done before I forked over the cash and my mechanic said it was as strong as he'd ever seen in a truck that old...and he actually drives a FSB. Combine that with the fact that the needle resides on the right side of the letter "M" in normal, I think it's pretty good to go.

I'm going to recheck the flanges where the y pipe meets the headers tomorrow and see if there's a small leak--that's about all I can think of....oh, and yes, I pulled codes just for shits and giggles and got the all-clear.
 

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Nope but it's very strong. When I bought it in May I had a hydraulic compression test done before I forked over the cash and my mechanic said it was as strong as he'd ever seen in a truck that old...and he actually drives a FSB. Combine that with the fact that the needle resides on the right side of the letter "M" in normal, I think it's pretty good to go.

See post #16.........
 

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I assume you're reminding me not to trust the stock guage? I probably wouldn't except that it seems to confirm what the mechanic told me. Should I second guess it?

Yeah Rev, I think I would---'specially if you like the truck and wanna keep her. The stock gauge only tells you that there's at least 6psi (5?) but won't tell you if you have 40 or whatever. I'd spend the $30 and get a good mechanical gauge for both piece of mind and to eliminate any other larger probs that you have. Cheap insurance. Cuz I'm thinking you may have a bad connecting rod bearing (like I did) since you're hearing the noise near the pan side. Fwiw the reason my knock in the vid seems louder is that I also had a fried ring and a scraping piston caused by major overheating. Oooh oooh, but I managed to fix it all while the motor was still in the car. It's a pain but it can be done.

Buenos suerte.........
 
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