Cant figure out source of LOUD noise above 55mph

[flatbed620]

I have a datsun 620, recently started making a loud noise above 55 mph going uphill usually. It is a loud noise sort of like loose sheetmetal or something, if i slow down it gets better and sometimes goes away. If I push in the clutch it stops immediately. Doesnt do it all the time, but is really loud when it does do it. Sounds like its going to come apart or explode.

 

So far.... have checked the center bearing, it looked rotten so I used DatsunMikes fix with rubber strips, didnt change anything. Checked all fluids- fine. searched everywhere externally for anything loose and cant find anything. No exhaust shrouds or anything, exhaust is newer. Everything seems tight.

 

Anyone ever experience this? Any ideas would be helpful!

[Rustina 510]

I was having a vibration noise when hitting 65 mph. Turned out to be bad rear tires. Swap tires and see of she still rides ruff

[datzenmike]

Shake the muffler and tail pope and see if it's hitting the frame or X member somewhere.

 

Is the spare tire secure at the back?

[flatbed620]

I was having a vibration noise when hitting 65 mph. Turned out to be bad rear tires. Swap tires and see of she still rides ruff

[flatbed620]

I recently put a set of factory dualies on the rear, it was doing it before and is still doing it now.

[flatbed620]

Shake the muffler and tail pope and see if it's hitting the frame or X member somewhere.

 

Is the spare tire secure at the back?

 

 

I checked the exhaust, I found I could move the tailpipe up & down, it seems the joint where the exhaust goes into the muffler is bad because it rotates at that point, (looks crimped - not welded) that maybe the cause, had the exhaust put on not long before this happened, I will update.....thanks again Mike.

[Kisor]

If you push the clutch in and it goes away I would start there. May be a spring in the disk or a piece of the clutch cover loose or broken.

[datzenmike]

Clutch in removes the load of the motor from the rest of the drive train. The motor is at idle and not twisting it with torque. This where the exhaust can rub against things.

[flatbed620]

Clutch in removes the load of the motor from the rest of the drive train. The motor is at idle and not twisting it with torque. This where the exhaust can rub against things.

 

You called it Datzen Mike, the exhaust was rubbing against the heat shroud where the cat used to be, and the muffler was defective. I started it up when still cold and checked around the exhaust, when I pushed on the side of the muffler I duplicated the noise, just not as bad because it was at idle. Something inside the muffler was loose (only 3 mos old) and rattling around, that with touching the heat shroud made an awful noise like the truck was coming apart.

 

You are the man! Thanks again.