1987 GL-10 Turbo wagon strange rattling noise

[backwoodsman7]

Hi all,

Hoping to get some hints on what this might be from those more familiar with the car than I am.  It's sort of a hollow rattling sound that from the front seats seems to come from the front, right of center.  It changes volume with throttle setting, most prominent when applying a little gas but not a lot.  It doesn't change volume or frequency with speed, i.e. it sounds the same at 25 as at 45.  All CV joints are good, nothing is loose in the suspension, and the car drives fine.  2wd or 4wd doesn't matter, sound is exactly the same.  There's no noticeable vibration in the car or steering wheel.  It's gotten worse over the last couple thousand miles.

Thanks in advance for any ideas.

Edited March 6 by backwoodsman7

[moosens]

I can see you’re not in the real rust belt. But still one thing I would take a look at is the center bearing mount of the two piece prop shaft. It’s prone to rust and hobble around a bit. 
 

If that’s not it I’ll put my brain back to work but not at the moment. Good luck. 

[backwoodsman7]

3 hours ago, moosens said:

I can see you’re not in the real rust belt. But still one thing I would take a look at is the center bearing mount of the two piece prop shaft. It’s prone to rust and hobble around a bit. 
 

If that’s not it I’ll put my brain back to work but not at the moment. Good luck. 

Thanks for the reply.  It'll be a few days before I can check anything on the car, but I'll take a look at that.  In the meantime, wouldn't that be speed-sensitive, faster & louder at higher speeds, and different with 4wd engaged?  This is the same regardless of speed, and 4wd makes no difference.

[88SubGL]

Are you sure it’s not a heat shield on the exhaust?

[Rupart]

hi,  the exhaust pipes on the orig cars have an inner pipe inside the outer pipe,, it is actually 2 layers. the inner pipe gets rusted and eventually breaks allowing it to sag and rattle against the inside of the outer pipe. i've seen this on almost all of my old subarus (80's). best way to check is get under and just bang around on the pipes , rubber mallet is good , even just by hand with base of your fist.   check all along front to rear , muffler too.

[backwoodsman7]

4 hours ago, 88SubGL said:

Are you sure it’s not a heat shield on the exhaust?

2 hours ago, Rupart said:

hi,  the exhaust pipes on the orig cars have an inner pipe inside the outer pipe,, it is actually 2 layers. the inner pipe gets rusted and eventually breaks allowing it to sag and rattle against the inside of the outer pipe. i've seen this on almost all of my old subarus (80's). best way to check is get under and just bang around on the pipes , rubber mallet is good , even just by hand with base of your fist.   check all along front to rear , muffler too.

Thanks for the suggestions.  These sound likely because they wouldn't be speed or RPM sensitive.  I'll check them out when I have a chance.