What is this awful noise?

[abcdefghii]

Trying to figure out what this noise is:



It started a while back, I think after I had changed the timing chain, cover etc. It only does it when I'm on the brake pedal and with the wheel turned hard. Wheel straight, no noise, not on brake pedal, no noise.

At first I thought it was the fan hitting something, but it's not that. I can't see anything that it could be and having to be on the brakes doesn't help since I can't look under the hood at the same time. Makes the sound regardless of it in gear, park or neutral.

I'm stumped and it's a hateful sound! Truck is an 81 D150, 318 with 727 trans.

Thanks

 

[Dana67Dart]

does the frequency of the rattling increase with engine RPM

somethings that come to mind

fan hitting something
hydraulic line flexing and getting hit by the fan
flex plate hitting something

the frequency of the rattling sounds around engine RPM.

do you know where your 10mm socket is?



did you use a hammer to get the harmonic balancer on or off?




Get a buddy and start hunting.

 

[abcdefghii]

Eureka!

Fan hitting the passenger side of the shroud, weird that it only does it while I'm braking. The fan has about 1" clearance on the driver's side and next to none on the passenger. When I replaced the timing components I also swapped in a new radiator, the bolt holes line up with the shroud, but it must be just out of position.

Dunno whether to trim the shroud or what yet, but at least I know the cause.

 

[Dana67Dart]

Loosen the engine mounts and move into er a 1/2"

Also maybe replace the mounts

 

[abcdefghii]

You know, I bet that if what caused it ... I had to loosen the engine mounts to raise the engine to get the oil pan off.

The mount do need replacement, time to go look into how much of a headache that will be

 

[Dana67Dart]

Do yourself a favor. Pull the distributor.

And if column shift, disconnect the linkage, if manual, disconnect the clutch linkage.