1 Lucky Texan

I remember nothing about those sizes, but was gonna suggest Datsun convertible as my old SRL311 had a valve.

yep, check https://www.troublecodes.net/subaru/ for a list of codes.

yep, 22oz for the outback, I think my WRX is less, maybe around 18???

whoa!!!! My dad had one, I swear aircraft can land on that hood! It's kinda like driving a waterbed down the road. You can be doing 80-90 and it's just like doing 50. You look down at that weird speedo and go , yikes, better ease up.... parking it was a challenge at times.....

I have read several times that the H tube or orifice w'ever can make a 'hooting' noise in an overcharged system.

My 2 experiences was that I felt a little improvement. Not unexpected since new struts should feel better than old/worn ones? I have read that KYB claims new struts from them are 15% stiffer than Subaru's OEM spec. Not sure if that's across all years/models though.

i know it's random, but maybe at every opportunity, have someone start the car while you listen with the hood up for the location of the noise? i THINK IAC valves can buzz. Early 90s have had buzzing ABS pumps, but I don't think that will prevent starting.

Sometimes, selecting a lower gear reduces strain on the engine and increases coolant flow. Make sure debris/dead bugs hasn't built-up between the condenser and the rad.

are you keeping the car? If so, get the KYB. Very likely you also need strut mounts. KYB may have some assemblies now, but I forget what years.

yeah, that sounds horrible, but , being across all cylinders makes me wanna say it COULD be slipped crank timing. That is, when the valves are fully closed, the piston is not at TDC.

check timing? maybe off by a tooth. They car run but be down on power. if it seems like the car hasn't had great carein the past, certainly possible to have more than one issue.

very unlikely, 'warped' (usually uneven deposits from pads, extremely rare to actually 'potato chip') rotors would be felt when applying brakes. Not to say stuck calipers could cause issues. https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjRosfmsZbxAhXDG80KHWfmBDMQFjAAegQIAxAD&url=https%3A%2F%2Fcentricparts.com%2Fgetmedia%2Fbd69395a-b65c-481d-93f7-b26b1bd0638d%2FCentric_and_APC_Technical_Whitepaper_B1-Warped-Brake-Disc-8-2018_1.pdf&usg=AOvVaw2Syl_CnageQ47I6fsJZy3W check toe in the front. I don't recall the first page but, inner tie rods, ball joints OK? Maybe bad steering rack bushings could do this???

fluid level OK? did Mom's car sit unused during the recent slow-down such that there could be rodent-chewed wiring or???? just hoping it isn't internal......

triple check breather and PCV hose routing I guess. in the 'old days', oil smoke at startup, and on the highway after - an abrupt foot off accel. , wait a few yards, then foot on the accel. induced smoke puff - often was a sign of bad valve seals I think?

smoke smell fuel-ish or oil-ish or sweet like coolant? if you suspect fuel is getting in the oil, don't neglect oil changes. maybe PCV valve is stuck open?

drain the oil, swirl a magnet around and see if you get metal? or send oil in to Blackstone labs?

the only way I got an axle out of my daughter's Impala hub was a little heat and penetrating fluid - after much force with 3 jaw puller pushing on the axle and an impact tightening it and a big hammer, etc. 20 seconds of propane at 6 and 12 o'clock. didn't car about any rubber as everything was getting replaced anyway. Becareful not to start a fire. car was rust free too. My guess is, there's enough moisture can condense or wick? on the splines over the years to make rust due to limited chance of drying out the tight space?

hmmmmm, I have no experience with models this old, but, have you recently serviced the trans? Did you use synthetic lube?

Man, I could not even find a good video on using manifold gauges. I use the them for vacuum application and charging, etc. But the whole pressure ratio thing is hard to discern for me. I can tell you, the system can make a 'hooting' noise if it is overcharged so, there's that. It is sometimes helpful to use a box fan to blow into the radiator too I think.

Just didn't know if the avls/var. valve system has them.

Ido - any oil screen issues on this car?

until you get into dual climate, most cars have 3 'flaps' with electric servo motors/controls. A flap/door for fresh/recirculate, one for defroster, and the one I think stuck or failing on your car us usually called the 'blend' door I think. FSM or some diagram from an image search might show you it's position in the car.

way to stick with it.

Gen 3 Outback Legacy headunit radio a/c climate combined this thread may have some interest for people fighting a bad radio in a Gen 3 https://www.subaruoutback.org/threads/jdm-hvac-alpine-stereo-install.533355/#post-6114611

if the 'frequency' of the shaking is closer to 4:1 with wheel rotation, than 1:1 = driveshaft.