GeneralDisorder

Yes you need to pre-torque the bolts then back them off.

Denso or Koyo for radiator. Aisin for water pump. Mitsuboshi belt, NSK/NTN/Koyo idlers. NTN tensioner. Dealer HG. Order the gasket for a 2008 STI. Part number ending in 770. All other gaskets from Subaru. GD

I just ordered one for an 84. They have clutch cables. No worries. Call Lithia Subaru in Oregon City, OR. Talk to Matt. I doubt the rear main seal is discontinued. I buy parts like that all the time. Rear main part number is 806776011. GD

HG's need to be done. They are leaking externally. That's a fact. I don't even have to look. Needs a new radiator and hoses if it hasn't been done. Plastic. Rubber. Fail. Timing belt is WAY overdue. 105k or 10 years whichever comes first. Could break anytime. Change immediately. GD

The sti gaskets are MLS.

The head bolts should be fine. Need to machine the heads flat. They are likely cupped. GD

Unfortunately no it does require belt removal.

His 03 Impreza uses an EJ25. That gasket will not fit a 2.2 GD

Use the factory gasket part number ending in 642. Its for a 2004 STI. GD

MUST buy clutch cables from the dealer. Aftermarket cables don't work (for long) on Subaru's. Unfortunate but that's the reality. GD

Value is subjective. Depends on if you are going to use it or sell it. Its resale value will be considerably reduced with a 2.0 swap. And it won't be as fun to drive. If rust was a huge concern on this body why was it worth $4k?

Well he paid $4k for it. So shouldn't that mean its worth putting in $3k to get it back to better than when he bought it? Depends on rust I suppose. That's never a concern here. GD

The failure rates vary. And surprisingly it depends on factors you wouldn't expect like how hard the car is driven and how much regular body flex is taking place due to acceleration and cornering loads. The 05-09 Legacy platform (especially turbo models) are notorious for too much core support flex and premature radiator failure. The 02-07 Impreza has the core support reinforcement beam so not as common. There's too many factors to be considered so we just swap them after 10 years. Usually the hoses are junk by the timing belt interval and often so are the head gaskets so we are routinely doing HG/Rings/Timing/Radiator jobs often with a clutch as well. Seems like that's the "105k service" on '99 to '10 single cam engines. I haven't seen much to indicate aftermarket is particularly inferior to stock. We use Koyo and Denso almost exclusively and I haven't had any repeat failures that I can recall. GD

93 would likely be the yellow plastic plate. I've seen them on 93/94's. GD

That usually means the HG'S are starting to go. Or you have a bad cap. GD

What you paid for the car is of no consequence. Put that out of your mind. It's in the past and has no bearing on this situation or "the math". You already own the car so for the purposes of this new math you paid $0 for it. Would you pay $4k for it in it's current condition? Of course not. So you're taking a loss. That's already done. Set in stone. Trying to save money going forward by repairing it the wrong way isn't going to redress that balance. It's done. You lose. End of math. Reman short block is $2150. Here's the math. What car could you buy for $3k (short block, gaskets, cylinder head work, and timing components) that has a brand new engine with ZERO miles and comes with a 3yr/36k warranty? Answer: Only the one you currently own. The HP loss isn't a static number. The loss is the entire area under the curve and the peak loss is much higher than 12 HP because you can't spin the 2.0 to redline and your gearing and shift points aren't setup for its power band. Like I said it's a mistake. GD

To know for sure you will have to get out a meter and check the resistance of the CTS against the service manual chart for resistance vs. temperature, check the EGR solenoid resistance against spec (around 35 ohms), and check for O2 sensor voltage switching (usually between about 250 and 750 millivolts) and/or check the O2 sensor heater circuit for continuity. In all likelyhood you do need these sensors - they are all common failure items. But don't troubleshoot with VISA! TEST, VERIFY, REPLACE. Having waited so long that you have three codes, you now have a much higher chance of these all being some kind of wiring issue like a grounding problem, etc. Have to rule it out with real diagnostics. The computer can't help with that part. It only gives a general direction (maybe the wrong one) GD

Find an independent glass guy. As for pulling out a used one - good luck. That's more work than I would care to do. I would rather repaint another hatch. Incidentally painting isn't that difficult at all. Its quite easy to have some paint mixed to match a panel and who cares if its blended into adjacent panels - no one will notice on a car that old. Fresh coat of clear and it will look better than the whole rest of the car. Really though - shop around. Even at 460 that's pretty reasonable. How much duckery are you prepared to go through on this ordeal? I spend a couple of my billable hours screwing around with some used junk and I could have just written a check and walked away to greener pastures. But to each their own. Glued in auto glass isn't a skill/tool set I care to aquire. I'll gladly have Hose A or Hose B deal with that hot mess. GD

Get a reman short block from Subaru. 3yr/36k warranty. You don't want a 2.0 in that heavy pig. The gearing and rev limiter is all wrong and it will be a dog. Kills resale value too. Just don't. GD

http://www.killerbmotorsport.net/oiling-products/oil-control-valves/2002-2007-wrx-sti-oil-control-valve.html

Interesting. Funny notation to that seal though - silicone garden hose washers are a perfect fit and will never go hard. Also cheap in bulk. GD

http://lmgtfy.com/?q=How+long+do+radiators+last GD

We recommend replacement of any radiator that has hit 8-10 years. We see failures every summer on 10 year old factory units. For the ~$250 it costs when you are already in there doing timing, etc, its not worth the risk. GD

Yes the radiator is plastic. Hoses are rubber. They have a useful life of 8-10 years. If you don't then one day it will just fail and that day will come before you need another timing belt. GD

Do not buy ANY gaskets from ANYONE but the dealer. Got it? Reuse the head bolts. Mahle is junk. Nippon Reinz makes the factory gaskets. GD