DaveT

Pull it apart, see if it looks chewed up. If not, regrease and reboot it.

A mechanical gauge tapped into one of the ports on the pump. At least for situations where you are troubleshooting.

It takes longer for the bubbles to start in the recovery tank. The gasses have to push all of the coolant back through its hose first. Any other leaks in the system complicate trying to sort out what's happening. Steady stream is not a good sign. Smell of exhaust is not a good sign. In time, a line of black crud can build up at the level the coolant sits at in the recovery tank. That's from exhaust, same thing, not a good sign.

If you have to move the ac compressor, you can just unbolt it and flip it up and back while it's hoses remain connected. If the pipe groove and pump socket are clean and nor pitted, a new oring should seal that joint. I've had good luck with plumber silicon grease if it's all clean. If it is pitted, a small amount of rtv to fill the gaps has worked. Pressure tests won't confirm headgaskets until they are very well blown.

Yes they are 4 or 5 books. About 8-1/2 x 11. Lots of details in them that are left out of the generic car manuals. Iirc, mine are section1, sec2&3 , 4&5, and 6.

Yeah, I was confused by th question. there is a flat spot on the rod, and the nut and faces on the end. What special tool? I just use regular metric wrenches.

30 seconds isn't long enough to get everything re primed. What I usually do is check a socket adapter in a drill, with a 12mm and use it to turn the oil pump for a while after installing it, but before putting on the timing belt.

There should be a lever and clamp on the choke. Can you post a picture of the carburetor you have?

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.