sounds like an exhaust leak but I cannot get it to go away replaced y-pipe gasket any recommendations 

it's a 1991 Subaru Loyale

Is it leaking?  

I can read your post two different ways….”I can’t fix this exhaust leak…” or “I thought it was an exhaust leak but maybe it’s something else ….”

which one is it?

Use hands or paper immediately after starting a cold engine and you have a short time to run hands or paper around the entire circumference of the exhaust and work front to back of the vehicle to look for leaks. Might have to try a couple times.  

Y pipe donut gaskets are troublesome. Grind the exhaust housing where the gasket sits down to remove rust and make smooth with die grinder. Use new bolt and spring hardware from Subaru.

Heat shields vibrating?

Axles.  Inner joints are the typical source if it’s doing it under load.  Often just repacking with fresh grease will fix it. The old grease may be gone or pour out of the boot like soup.

You sure it’s not light lifter tick? 

Cheers 

Bennie

I had trouble with the gaskets between the head and exhaust Y pipe.  I made my own.  I used fiberglass body repair mesh.  Use a new normal gasket as a template. Start with a piece of aluminum foil.  Stack up 4 layers of the fibreglass, and work copper RTV or [higher temp] into each sheet, stacking them.   You only need the RTV where the metal clamping areas are, not where the holes will be.  Use a piece of .001" brass shim stock for the final layer.  Put this assembly between 2 flat plates, and put something like 20-30 lbs on top of it.  Let it set for several days.  The RTV will cure very slowly.  When it's cured, use an exacto knife and or gasket punches to cut them to shape.  When installing them, aluminum goes to the head side.  Use lock washer.  Re check after a drive or 2, to make sure the nuts stay tight. 

The combo of RTV and fibreglass will squish more than the typical hard gaskets, and seal up.   The fibreglass won't burn away, and will protect the RTV from the exhaust gasses. 

Note - I used the brass because I also made stainless exhaust pipes, and aluminum and stainless do not get along well in the environment involved.

1 hour ago, DaveT said:

I had trouble with the gaskets between the head and exhaust Y pipe.  I made my own.  I used fiberglass body repair mesh.  Use a new normal gasket as a template. Start with a piece of aluminum foil.  Stack up 4 layers of the fibreglass, and work copper RTV or [higher temp] into each sheet, stacking them.   You only need the RTV where the metal clamping areas are, not where the holes will be.  Use a piece of .001" brass shim stock for the final layer.  Put this assembly between 2 flat plates, and put something like 20-30 lbs on top of it.  Let it set for several days.  The RTV will cure very slowly.  When it's cured, use an exacto knife and or gasket punches to cut them to shape.  When installing them, aluminum goes to the head side.  Use lock washer.  Re check after a drive or 2, to make sure the nuts stay tight. 

The combo of RTV and fibreglass will squish more than the typical hard gaskets, and seal up.   The fibreglass won't burn away, and will protect the RTV from the exhaust gasses. 

Note - I used the brass because I also made stainless exhaust pipes, and aluminum and stainless do not get along well in the environment involved.

i use 3 layers of steel sheetmetal and ring the holes with copper wire and coat it all with copper head gasked dressing they seal the worst headers and there reusable im on round 3 right now and still no leaking

 

back to the ops issue from what it sounds like is pinning or knocking try adding 92 octain gas or retarding the timing a hair if it goes away its a timing issue or a bad plug issue or maybe even carbon build up on the piston creating a hot spot ether way try better gas and or adjusting the timing

 

I have had  the inside pipe of the Y pipe cause my noise problems. I have never done an autopsy on the how and why but I found to drill a hole in outer skin that we all see and screw a metal fixing screw through it and either into or against the inner skin. Noise gone, until screw came out. Next screw got silicon sealant to hold it in place

I tried looking for holes in the exhaust and  I just replaced the Y pipe to header gasket here’s a video if anybody can tell what the sound is https://drive.google.com/file/d/1z3RonlfegrhahdQQ7wqLB_02kvI8GRiz/view?usp=drivesdk

On 5/27/2022 at 8:57 PM, ferp420 said:

 

back to the ops issue from what it sounds like is pinning or knocking try adding 92 octain gas or retarding the timing a hair if it goes away its a timing issue or a bad plug issue or maybe even carbon build up on the piston creating a hot spot ether way try better gas and or adjusting the timing

 

This.

My GL Wagon EA82 would sound like a rattling tin can under load with "regular" fuel. With Premium Fuel the pinging pre-detonation went away.

 

If it still persists with Premium Fuel then have a friend Rev the engine with your head under the car to determine where the exhaust leak or rattle is coming from.

I will try 

I put premium in and it didn’t go away I Took off the gasket and found it it was exploded I’m going to make my own gasket and hopefully it will fix it here’s an image of the blown up gasket i’m also gonna grind down the y pipe with a wire brush to make it as flat as possible https://drive.google.com/file/d/1oX6pjdbuj2hrfZfkyQg6y5xw176ECNt2