80 series clattering on acceleration (2 Viewers)

[kristofferson]

Is this link not working...?

LC2.wav | Powered by Box

app.box.com

(that's for .wav)

and this one is for .mp3...

LC.mp3 | Powered by Box

app.box.com

(I couldn't get youtube to accept an audio file...)

 

[izzyandsue]

Just do a video, sound will work

 

[roadstr6]

Listened to the video. It’s not a steady sound. More like a rotational clackety clack. It seems to come and go. Check the belts, pulleys and fan clutch for anything loose. Check that the fan is not hitting the shroud. Check idler pulleys. Grasping at straws here, bud. Hard to diagnose without being able to see in person. It doesn’t sound like an internal engine knock or spark knock. I assume temp and oil pressure are normal, right? It has something to do with a part that spins. Busted motor mount could cause the fan to hit the shroud I guess, but I’d think you’d hear that more at full throttle. Does a/c on or off affect the sound?

 

[Green Hell Mustang]

So, my truck does this. It does it under similar conditions (under acceleration/under load, low RPM, never in neutral) and worse if it's been warmed up or has been driven for a few hours. It's most noticeable on Black Mountain in Western NC. It's been doing it for a while. I always chalked it up to valves being out of adjustment. It's definitely not as bad as the audio clip you supplied and it's infrequent. I don't really want to break out all the shims and micrometer to adjust valve clearance. Fishing out the old shims from the top end isn't my first choice of how to spend my Saturday, I can think of better ways to destroy my lower back. I figured I'd have my engine out one of these days to do the head gasket, I guess I'll check them then.

Since you have an audio file, @OTRAMM might be able to give a better diagnosis of what it could be.

 

[kristofferson]

S

Listened to the video. It’s not a steady sound. More like a rotational clackety clack. It seems to come and go. Check the belts, pulleys and fan clutch for anything loose. Check that the fan is not hitting the shroud. Check idler pulleys. Grasping at straws here, bud. Hard to diagnose without being able to see in person. It doesn’t sound like an internal engine knock or spark knock. I assume temp and oil pressure are normal, right? It has something to do with a part that spins. Busted motor mount could cause the fan to hit the shroud I guess, but I’d think you’d hear that more at full throttle. Does a/c on or off affect the sound?

Interesting that you mention the fan hitting the shroud, I know I've heard a buzzing noise that sounds like that recently, too. Belts, etc., seem to have good tension/not loose. Temp is good. In hot weather, my oil pressure drops pretty low - it used to stall out if I was stuck in stop/go traffic on a really hot summer day, but about a year ago I started putting 10W-40 and haven't had that issue since. Whether or not A/C is on or off doesn't affect sound.

I will say, however, I did quite a bit of driving yesterday after adding a bottle of Lucas high octane and by the end of the day, it has caused the noice to reduce some (definitely not as loud as it was), but has not overcome it completely. Annnnd have the added benefit of very noticable zip! Like 0-60 in 30 seconds! (just kidding, but it does have a lot more zip, seriously!)

 

[roadstr6]

I think it would be worth your time to get under the truck, pull the front skid plate (splash guard - 4 bolts) and check all your pulleys real well. Check the harmonic balancer to make sure it's tight. Check the idler pulleys for worn / seized bearings and look for telltale signs of anything rubbing with the fan and shroud (look for plastic dust or belt dust). The HB bolt requires 300+ lbs of torque to tighten. If it has ever been removed by a PO, chances are it wasn't torqued to spec. It could be backing off. The idler pulley bearings are known to go bad, but usually they squeak and squeal to give you fair warning. You have the AC compressor, water pump and power steering pump up front..all driven by belts, pulleys or gears. Lots going on on the front side of that engine. Checking it won't cost you a dime. At the very least, you'll eliminate some possibilities and you can rest easier knowing that everything from the radiator to the front of the block is tip top.

 

[kristofferson]

I think it would be worth your time to get under the truck, pull the front skid plate (splash guard - 4 bolts) and check all your pulleys real well. Check the harmonic balancer to make sure it's tight. Check the idler pulleys for worn / seized bearings and look for telltale signs of anything rubbing with the fan and shroud (look for plastic dust or belt dust). The HB bolt requires 300+ lbs of torque to tighten. If it has ever been removed by a PO, chances are it wasn't torqued to spec. It could be backing off. The idler pulley bearings are known to go bad, but usually they squeak and squeal to give you fair warning. You have the AC compressor, water pump and power steering pump up front..all driven by belts, pulleys or gears. Lots going on on the front side of that engine. Checking it won't cost you a dime. At the very least, you'll eliminate some possibilities and you can rest easier knowing that everything from the radiator to the front of the block is tip top.

Cool man - thanks Dave, always appreciated!

I'm planning to sell it soon (and change things up a bit and get an '06 or '07), so I want to get everything on my 40th in good order before putting it up for sale. Thanks again

 

[Rice]

Not much to go on but, from the recording, exhaust is the first place I would focus ... not for leaks but for a pipe rattle against something. Begin with the exhaust heat shields on the motor .... check that they are secure. Then work your way down the Y-pipe and the frame brace that is inside the passenger side fender. Then keep working your way back to the Cat, etc.

Another test ... what happens if you hold the brake and give it gas?

Question .... was this sound something that was sudden or did it develop over time?


A quick note .... be careful about using Octane boosters as some of them are bad for Cats and O2 sensors.

 

[kristofferson]

Not much to go on but, from the recording, exhaust is the first place I would focus ... not for leaks but for a pipe rattle against something. Begin with the exhaust heat shields on the motor .... check that they are secure. Then work your way down the Y-pipe and the frame brace that is inside the passenger side fender. Then keep working your way back to the Cat, etc.

Another test ... what happens if you hold the brake and give it gas?

Question .... was this sound something that was sudden or did it develop over time?


A quick note .... be careful about using Octane boosters as some of them are bad for Cats and O2 sensors.

Thanks Rice - it’s developed over time. Just more noticeable in hot weather. If I hold the brake and give it gas, it doesn’t make the sound. Mostly when moving forward when the gas the pedal is “hovering” between gas and no gas (lightly accelerating, really).
I’m just going to take it in to a mechanic as I’m short on time to tinker.
I’ll post a reply once it’s solved just in case this helps anyone else in the future.

 

[Green Hell Mustang]

Thanks Rice - it’s developed over time. Just more noticeable in hot weather. If I hold the brake and give it gas, it doesn’t make the sound. Mostly when moving forward when the gas the pedal is “hovering” between gas and no gas (coasting).
I’m just going to take it in to a mechanic as I’m short on time to tinker.
I’ll post a reply once it’s solved just in case this helps anyone else in the future.

I'd be very interested to see what a mechanic has to say about it. Everything you've mentioned is exactly what my truck does, to a lesser degree.

I do remember reading a thread on the '80 forum' about someone who had similar noises coming from their truck. One of the explanations that was mentioned was that the torque converter may be making the noise. One of the things that may come in handy in this situation would be a set of 'mechanics ears.' That is a more expensive set, there are cheaper ones.

 

[GarnerFJ40]

Yep, have to chime in. Mine also has the same. Does seem to come and go with fuel rating. I've also chocked it up to being valves needing adjustment, but willing to see where this goes!

 

[CMVT03]

Thanks Rice - it’s developed over time. Just more noticeable in hot weather. If I hold the brake and give it gas, it doesn’t make the sound. Mostly when moving forward when the gas the pedal is “hovering” between gas and no gas (lightly accelerating, really).
I’m just going to take it in to a mechanic as I’m short on time to tinker.
I’ll post a reply once it’s solved just in case this helps anyone else in the future.

Hello, any luck diagnosing this one?
My 97 LC (200K) is doing the exact same thing. Just a little rattle with light pressure on the gas, only warm, when in gear, not idle. I haven't dug into much yet.... Looking for clues in this thread.

It reminds me of the sound my sister's Civic made after I replaced her exhaust manifold with a cheaper knock-off version. Almost like a tinny harmonic thing. Maybe it is an exhaust issue.

Or, maybe something with the transmission, or perhaps diff/axle teeth (as in this example). I will follow up if I get a handle on it, but appreciate any feedback you might have had in the 6 years since this thread went dormant.

Thanks,
Chris