DaveT

Hitting things when bearings are going to take part of the impact is not good. Pressing is much less likely to damage the bearings.

Get the retired ones...

Run it up to normal operating temperature, it should unscrew easier.

Be very gentle. Dry light brush, maybe test some more hidden part if it needs water / wiping.

12.6 confirms that it is not charging. Especially at both locations. Possibly ground, possibly 1 of the 2 wires or the circuit feeding them is open.

Odometers have a clutch to prevent counting backwards. Some [if not all] also have a booby trap rigged to mark the number wheels if they are tampered with, so you have to be aware and careful if you want to mess with them.

Once you go through EVERYTHING, the GL can be good. I drive one now. If "your" 87 hasn't had a reseal, it's due. Timing belt change interval for high reliability is 50K - that's me being extra careful. The original interval in the FSM was shortened by Subaru years ago. When you do timing belts, replace the 3 idlers or their bearings. Coolant system maintenance is #1 priority for reliability. Get a FSM. Read lots of threads on here, it's an older car, it's going to need stuff taken care of to be reliable again.

What voltage readings do you get on the battery while at idle, and revved? What I have seen on my GL / loyales is when one of the brushes in the alternator wears to the point of loosing contact with it's slip ring, the dash lights glow dimly at first, then eventually, it's not unusual for a number of them to glow. The wiring involved with those lights is in the 2 pin connector. There are at least 2 other connections in the wiring between the back of the alternator and the lights.

Be sure to check the cooling system also.

TIG welding stainless is a dream. As long as the 2 pieces touch, you barely need any filler. The exhaust pipe is about. 06 thick, so it's not too bad, but for your very first welding, thicker is easier.

With an ohm meter - when the probes are open circuit, that is infinity ohms, so the display will have some symbol to indicate open loop, or over range, or similar. When you touch the probes together, it should display a very low number, depending on the sensitivity of the meter and or range it is set to, since that is near zero ohms. It's normal to get a few tenths of an ohm in that case. I don't know what the common readings are for that sensor, without looking in a factory service manual. Note - not all sensors can be fully tested with an ohm meter.

I have no way to know for CA. It did pass CT emissions. The cat I got from one of the online tuner stores, it's 2" in & out, 3 way cat, so only need one.

sometimes that will work. Sometimes leaks only happen when hot, sometimes only when cold. It won't find the tiny pinhole head gasket beginning failure. But it will make some ordinary leaks easier to find.

That also usually means the axle nut is tight, so that stuff should be ok. Loose axle nuts can ruin spline in the hub and axle, in addition to the seals and bearings if it goes on long enough.

Start on steel over 1/4" thick. Or stainless. Stainless wants to weld.

I've been driving these GL / Loyales since 1988. A couple of them got past 200K miles. Never had a front wheel bearing go bad. [side note, I am almost done with the first rear wheel bearing repair I've ever had to do to one of these cars] If it's making some kind of constant noise, maybe it's a bearing - I'd think if a bearing was bad, it died due to contributing factors like the seal/s are shot or the axle nut got loose.

I'm not 100% sure, but I think I've had a lot less problems with the passenger side boots since I made this: http://www.dynahoedave.co.nf/exhaust.html The original exhaust puts the cat nearly under the inner boot, cooking it pretty well.

Usually, they click, and it gets worse in sharp turns, so try the suggestion above. Aftermarket axles are junk [with a few exceptions that can be found searching other similar threads] I have only rebuilt OEM Subaru axles, many times. [they key is to notice the torn boot before they start clicking] Far better than the typical aftermarket ones. It is harder to find OEM ones now, I'll admit.

I have limped them around with mildly failing headgaskets, while resealing a spare engine. Forget stop leak type stuff. It is meant to keep 15psi liquid inside, not 100s of psi hot gasses out. Best chance is make a zero pressure cap. Before every cold start, check level and air, add water if low. Short drives, not hours. If it is to the point where it pushes a lot of coolant into the recovery tank, that's about the end of it. It will get progressively worse. Any over temp will accelerate the problem. I'd consider removing the thermostat also.

If you use Fel Pro perma-tourque gaskets you don't retourque. As far as I know, oem still require it.

Yes, it takes time. Carefully watching can help avoid causing it to get worse while you hunt down regular leaks, etc. Fins can be cooler than the ends, as they are thinner, and loose heat quicker than the tanks. I have often found that after installing a new hose, the clamps need another twist of the clamp screw to reseal after a run cycle.

The one I had to do immediately went well. I found that my bearing splitter was a decent fit for it. I used 2 grade 8 bolts to apply pressure against the diff housing, and worked it off by gradually turning the 2 bolts. I'll probably put up a web page of the whole rear wheel bearing project in a few days. I just have to reassemble the brake parts and bolt the wheel back on now.

Hearing coolant slosh in the heater means significant coolant loss. That's not good. That means shut it off and get it full. The tests from what I have seen on the forum many times, often doesn't give accurate results, at least until there are many other signs making it obvious that the failure is the headgaskets. The procedure I wrote previously is how I determine if the headgaskets are failing. Run zero pressure, very and re verify no other leaks, known condition of radiator and heater. If all is well, any small amount of air gets worked out over several cycles. If air stays, or increases, especially if the recovery bottle gains fluid, not looking good for headgaskets. If coolant keeps going away, some other leak is more likely.

Some rust dust did fall out. I do have others that are stuck, and intend to get at pulling them so I can get anti seize in there before they REALLY get stuck... I forgot to spray some Kroil in there, off to do that before bed now...

upper hose sounds bad. If it was new, it's compromised now. With pressure, yes, anything not sealed well will be more likely to leak. How quickly did the leaking show up? It normally takes time for the engine heat to build enough to start expansion, where exhaust gas leaking through head gaskets is immediate. If the leak has advanced enough - tiny beginning failure can be very slow also.. The blockage if any has nothing to do with the leaking. The water pump can't make enough pressure to have any problem with being blocked. Radiator hot on one end and cold on the other does indicate no / low flow. Note, it won't flow until the thermostat opens. A little green on the brass connections isn't unusual. Stop leak is a worry. It would be very good to flow check the heater core also. If that is blocked, it can interfere with the thermostat opening as things warm up. You could rule it out by using a loop of heater hose in place of the heater core.