Well my 1998 Legacy outback wagon started up, I pulled the injectors and turned it over for about a minute (to get the oil flowing)  then hooked up the injectors and fired everything up, started right up

 

going to pull it out of the garage in the morning and let it idle for 30 mins or so and maybe then a little around town driving...

 

HOW MANY MILES before I should take it on the highway?

I wouldn't worry about taking it on the highway, there's nothing that will "break in" with a head gasket change. Just keep a keen eye on it for any leaks during the next week or so.

Yup, plug and play. I've changed mine and took off, just watch your temp. If it doesn't overheat in the first 30 min you're probably good to go.

I wouldn't plan on driving it cross country right away until you know it won't overheat or leak. There nothing wrong with taking it on the highway, head gaskets seal when the bolts are torqued. As long as everything was torqued properly, the cooling system is filled and burped of air bubbles, and its not leaking any fluids. Drive it anywhere you like.

Since a 98 OBW does not have a dash board idiot light indicating water temp, it is advisable to keep an eye on the temp gauge while driving. Your engine is prolly good to go, just watch the temp gauge.

When I did mine it took me about 1 mile to get to the highway.. from then I pulled over and did a few redline pulls It passed with no issue.

 

 

The worst I had was the oil burning in the cylinders because I manually coated the cyliner walls because I did not want rust to form.

 

*edit and this was 2 years ago

Edited May 23, 201312 yr by 1-3-2-4

on all freshly installed engines i run them no longer than 500kms and change oil on rebiuld ones 45 min of run time and change the oil this removes any debrie that may have found its way into engine

any tricks to getting the coolant flow started, I filled it last night and left it open, then fired it up this morning, took quite a while to even start warming up and even longer to get a LITTLE heat out of the heater

 

however I think I might have an air bubble or 2 because it did start to over heat in the drive way a little

 

BUT good news is the coolant is getting nice and warm and there is no exhaust coming out of the radiator like it was before...

fill rad with vent open not running till coolant come out the vent no bubbles then safe to put cap on and do runup to temp make shure fans cycle 2 times before you drive it fans should not run for more than 2 min max and rad should be hot when they turn on

I squeeze the upper radiator hose a few times to get coolant into the engine, it works to burp the air out. Worst case you can remove the upper radiator hose and fill the engine up through that.

 

When you say overheat in the driveway, did it get into the red zone? It will run hotter in your driveway than on the road. The radiator fan should kick on before it gets too hot though.

fans kicked on, but the gauge got a little under 3/4...  I have seen this on a few engines when they got air suck in them

fans kicked on, but the gauge got a little under 3/4...  I have seen this on a few engines when they got air suck in them

Yep this happened on my friends 2002 Forester, replaced the radiator and I had my Torque app running and I said to him by 208 F the fans should kick in.. well they did not so a few min later I was seeing temps of like 230F and I was like we have to shut it down now we have air in the system.. I cracked the lower hose and refilled again at the top and after that it was fine.

 

Btw I was filling with the car running but I guess it was a huge air bubble.

ok let it cool and it took a few more cups of coolant, this time it only got to 2 marks above 1/2, so maybe 2/3?  Also I noticed as it was cooling last time the upper radiator hose collapsed, this to me screams air in he system and air will compress and contract, esp as it changes temps

 

The hose opened back up when I cracked open the system

Edited May 23, 201312 yr by mightGETaSUBARU

Also I noticed as it was cooling last time the upper radiator hose collapsed, this to me screams air in he system and air will compress and contract, esp as it changes temps

It shouldn't be able to draw a vacuum even with air in the system, it sounds like your radiator cap is bad.

you're always supposed to fill these engines first through the top radiator hose, then through the radiator itself. Then burp the system to remove air. Not sure if you had read that or not when researching the job.

Hmm, looks like you should fill through the vent plug.

I opened up the op radiator hose and she took about 3 quarts of coolant  

 

Now we have a working heater and the fans are cycling great, one more cool down and fill and she is ready for a drive

Well so far over 100 miles and a little more than 1/4 tank of gas and she is STILL kickin'  

 

However I am going to need new exhaust manifold gaskets, they are ticking a little bit

 

Also does not seem to have he slight smell of burning oil the car used to have