1 Lucky Texan

I'm no expert so, hope others will respond; on some swaps, I think you have to move the cam gears over from the old engine.

search for it at www.scoobymods.com - they have listed TSBs in the past or, do a search on google for the entire name, and add .pdf to the search string.

sure, they are electro-mechanical and can become intermittent, plus, older cars could have poor grounds and other connections....nothing is 'ideal' like when new and the weakest link fails. I wouldn't say it's common, but I have read of relays doing this 2-3 times in the past. Who knows, taking it out and re-inserting it might wipe a little corrosion from it's terminals and it could work for 5 more years, or, it has burned-off a contact internally and is just worn-out. They aren't expensive and just getting a new one is probably the best move. But, for further diagnostics or just to satisfy curiosity, swap it with a different relay of the same type. See if the problem travels with the relay. You could also spray a little contact cleaner in the relay's socket.

^^^ good point !

I use manifold gauges, 'borrow' a vacuum pump from the parts store (dunno if they loan out gauges) and pull a vacuum for a while, then turn off the pump and monitor for a leak, if all looks good, close the valves, remove pump, attach a refrig can, open it, pop the valve athe top of the center hose to clear atmo air out, then, open both valves. The vacuum will pull a LOT in. Then, close the high side valve and start the car, likely there's enough in now to satisfy the low press cut-out and the comp. will pull in. Then, after the first can is empty, I attach the second can. It seems to help to boost thr rpms a few times to 2000 or so, for a several seconds. Our Outback has a label on the rad frame in front of the compressor that says something like 22-26 oz so, 2 'regular' cans is what I put in. If you are just going to try to add to a closed system, maybe just see if enough will go in? this is why most people use a pro for this stuff. Even when I do it now, I have to triple check myself as the procedure is so involved. Add to this trying to fit o-rings or valve inserts, leaking hoses (I've had 3 - only one under warranty way back) and folks reporting bad rev sensors, or weak relays (swap yours with another one that's the same - maybe headlights???) and taking shims out of clutches......it can get crazy. you might look around here;

there are some videos of Subarus on rollers or roller equipped ramps that can demo the function. With no load (other than internal friction) you can't get a good idea of how the AWD functions. And, it can make a difference if you have rear LSD or not.

hydraulic lifters? I've read some folks have used Marvel Mystery Oil or some other additives to help with lifter tick. rod knock is quite loud and gets very aggressive at higher RPMs, some youtube videos demonstrate it.

wonder if a little parking brake application could help? or, manually select 1st or 2nd - or D . I've read that programming biases the power differently if different gears are selected?

has it been recharged in the past? 14 year-old car could EASILY be low on refrigerant.

have you ever had evidence of rodents around the car? maybe some wiring harness was chewed?

does a 99 have the 'new style' timing belt tensioner? They can mimic rod knock. Though, I'd think you could get the sound while idling. Is your sound ONLY when moving?

there's no really practical way to turbo that car. Best approach would probably be a swap from a wrx but, still, a major project.

Thrill Driver !!!

I did the TB system on my WRX at under 70K miles due to it being about 9 years old. 2 of the idlers were very loose and one of those (toothed idler) wobbled slightly. Dunno if it would have last 2 more months or 2 years but, I have no regrets. The toothed idler is often the failure point.

gah - I guess I will replace the ex cam gears at the next belt service.

adult is the 'common', the hatchling 'looks' to be the 'alligator' species, though, kinda tricky to tell for certain. You seem to be just a little too far north of typical range for the Alligator Snapper. the chelonians are an extremely successful clade and 'probably' predate the dinosaurs by up to 10 million years....real survivors.

maybe check axle nuts? sure seems like it could be inner tire rods being 'central' in sound. some folks have had the little u-joint on the steering shaft go bad - though often they get stiff...... maybe test with a hose to the ear or mechanic's stethoscope while someone else works the steering wheel?

GD, does my 06 WRX have plastic cam gears? I don't recall anything odd about them from the belt service I did, but, didn't really pay attention either. Just trying not to screw-up the belt install.

it would be a shame to do the gaskets and have a rod bearing fail in a few weeks from having been over-heated. Though, it seems you didn't experience SEVERE heat....... does this only happen at highway speeds? If so, they all do that unless you do a battery disconnect reset before a road trip.

rust never sleeps

rooster, you might also consider posting a request over at www.subaruoutback.org thrown belt will cause an odd 'lope' when cranking. check youtube videos too - there may be 2-3 showing removal of the timing covers and how to check the timing. You might even discover that the toothed idler has fallen apart or the belt is broken.

SAFELY try tapping or rapping on the fans - maybe there's an intermittent motor failure? a rare failure could be the engine temp sensor. If bad, it might cause the ECU to think the engine is always cold. But I'd expect very poor running as the ECU would be 'choking' the car with excess fuel. it does seem like there was a significant gas 'bubble' in the block. get working OEM rad cap, and OEM thermostat, etc in the past, .it has been recommended to get the nose of the car up, sloped driveway or on ramps....run the car until the fans come on and it's at operating temp - make sure there is coolant in the overflow - ,rev the car a coupla times, - let the car cool. A little coolant will probably be pulled from the overflow. When cool, check the radiator level and coolant level.Then drive the car and monitor the levels and the temp gauge. Until you have confidence in the system, always check coolant level in the rad.

some folks will purp[osely use a little sal water and sun/yard 'exposure' to bring back that fine rust coat - just in preparation of using a phosphide rust converter. maybe try something like this now ?; https://www.amazon.com/VHT-SP229-Rust-Convertor-Can/dp/B002NUABUO/ref=sr_1_7?crid=ASQ2HT5FXKC3&keywords=rust+converter&qid=1562076113&s=gateway&sprefix=rust%2Caps%2C199&sr=8-7

yeah, you could dig around at www.opposedforces.com - probably find a diagram too.

nothing wrong with showing the parts guy your VIN number but, I doubt there's much chance for confusion on a PCV valve.