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300 sounds like a bucket of bolts at higher speed acceleration

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FrazerJames

300 sounds like a bucket of bolts at higher speed acceleration

Got the Bronco out on the highway for the first time today and was pleasantly surprised by the handling. Barely any movement in the steering wheel! What did surprise me is the noise coming from the 300. I mean, I know it’s a loud engine, but this seemed out of the ordinary.

1. At idle and normal around town driving speeds it’s not too loud. It’s a tractor engine, but not ridiculous by any means… (Idle at 650 and smooth up to 2000 rpm)

2. Acceleration in city driving seems normal sound wise. Or at least doesn’t shock me. I can also cruise at 65 between 2300 and 2500 rpm and it sounds fairly normal. (It’s a 3.08 and a C6 transmission)

3. Try to accelerate when already driving above 55mph and it sounds like it’s going to rip apart. Lots of loud clanking. RPM never goes above 3000 and I’m not at WOT because it sounds terrible. Also, it’s extremely slow to get moving (as if passing) at those high speeds, but that part doesn’t surprise me.

I suspect it could be any number of things - any thoughts on what I should chase first?

1983 Bronco 4.9 300 I6
Current Name: Whitney

kramttocs

Re: 300 sounds like a bucket of bolts at higher speed acceleration

Administrator

My first thought when just reading "bucket of bolts" + acceleration is pinging.

Scott
'Camano' 1986 F250 Supercab XLT Lariat 460/C6
'Chanute' 1980 F350 C&C 400/NP 435 - Gin Pole

But there ain't nothin' wrong with the radio

FrazerJames

Re: 300 sounds like a bucket of bolts at higher speed acceleration

Yeah, there’s not much to go on… I thought the higher speed might be an indicator on something in particular, but it’s a shot in the dark.

I’m just going to start with the basics… Timing, spark… And then I guess I’ll just go from there.

1983 Bronco 4.9 300 I6
Current Name: Whitney

kramttocs

Re: 300 sounds like a bucket of bolts at higher speed acceleration

Administrator

And it's definitely from the engine? Just noise and no vibration?

Scott
'Camano' 1986 F250 Supercab XLT Lariat 460/C6
'Chanute' 1980 F350 C&C 400/NP 435 - Gin Pole

But there ain't nothin' wrong with the radio

FrazerJames

Re: 300 sounds like a bucket of bolts at higher speed acceleration

No vibration, no. Just noisy as hell.

1983 Bronco 4.9 300 I6
Current Name: Whitney

ratdude747

Re: 300 sounds like a bucket of bolts at higher speed acceleration

Check your flexplate nuts... I've heard of people not getting them tight and making all sorts of noise like that.

I'd also suggest the harmonic balancer but usually that's also an idle noise.

If it's pinging, better get it fixed. Such was likely what broke the 5 of the upper compression rings in my 300 and forced a rebuild and bore job.

1984 F150: 300 L6, AOD, RWD. EEC IV / TFI, Feedback Carter YFA Carb. Stock everything but radio (for now).

1986F150Six

Re: 300 sounds like a bucket of bolts at higher speed acceleration

Administrator

In reply to this post by FrazerJames

Ignition timing? If you can, check the timing with a timing light or vacuum gauge. If the fuel tank is almost empty, put in a few gallons of premium and see if the engine sounds better.

Is the vacuum line attached to the distributor advance cannister?

FrazerJames

Re: 300 sounds like a bucket of bolts at higher speed acceleration

Thanks all. I’ll update on what it ends up being. It’s probably a bad pulley.

1983 Bronco 4.9 300 I6
Current Name: Whitney

FrazerJames

Re: 300 sounds like a bucket of bolts at higher speed acceleration

Ratdude, I think you may have nailed it. It a little quiet at idle, but I think I hear a rattle coming from the driveshaft pulley. Either that or the water pump.

Anybody think it’s a bad idea to remove the belts and start it up to for a minute to see which one? Although, I wonder how the sniper will react to no alternator power…

1983 Bronco 4.9 300 I6
Current Name: Whitney

Gary Lewis

Re: 300 sounds like a bucket of bolts at higher speed acceleration

Administrator

You'll be fine w/o the belts for a minute or two. Take the front belt off and see if that kills the noise. Then the back belt if you still have the noise.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

FrazerJames

Re: 300 sounds like a bucket of bolts at higher speed acceleration

I don’t think I can remove the back one without moving the 2nd one. Basically If I take them all off the big thing I’m losing is alternator and water pump. Everything else is accessory right?

So running for 2 minutes will be ok on a cold start I’m gathering.

1983 Bronco 4.9 300 I6
Current Name: Whitney

Gary Lewis

Re: 300 sounds like a bucket of bolts at higher speed acceleration

Administrator

Yes, you can run for a couple of minutes on a cold start w/o the water pump. But keep it as brief as you can.

Gary, AKA "Gary fellow": Profile

FrazerJames

Re: 300 sounds like a bucket of bolts at higher speed acceleration

Got to taking all the belts off today. The noise ended up being the water pump pulley. It’s kind of a dull thump when turned by hand. I suppose it’s new water pump time? Any other alternatives?

1983 Bronco 4.9 300 I6
Current Name: Whitney

Gary Lewis

Re: 300 sounds like a bucket of bolts at higher speed acceleration

Administrator

So it is actually the water pump itself? I’d replace it as that surely means the bearing is failing.

Gary, AKA "Gary fellow": Profile

FrazerJames

Re: 300 sounds like a bucket of bolts at higher speed acceleration

Yeah the whole pulley is sloppy. Ordering up a pump. Might as well do my Saginaw upgrade as well - I’ve got all the parts for it.

1983 Bronco 4.9 300 I6
Current Name: Whitney

Gary Lewis

Re: 300 sounds like a bucket of bolts at higher speed acceleration

Administrator

Yes, now is the time to make the swap.

Gary, AKA "Gary fellow": Profile