Check my logic on a possible small head gasket leak - Saab C900

So after 2+ months of wrenching to get my project C900 road-ready, I got it started and idled up to temp. And the temp kept going with no signs of the fans coming on, so I turned on the A/C (which automatically triggers the fans) when it got to around 3/4 on the gauge and it came back down quickly. I finally tracked down the problem with the fans (the relay that provides power to the switch was bad), so that's solved, but now I'm wondering if the head gasket has a small leak.

When the car gets up to temp I'm seeing a little steam out the tailpipe. Bear in mind, however, that this car hasn't run much in the last three months, so I wouldn't be surprised if there's a bunch of accumulated moisture pooled in the mufflers. However, there is another symptom. When, and only when, the engine is at operating temp, I'm seeing occasional bubbles from the radiator overflow into the expansion tank. The radiator hoses get firm as the engine heats up, not immediately upon starting; in other words, what I consider normal.

The whole cooling system is new: radiator, water pump, thermostat, hoses, electrical switches, and coolant. Prior to adding new coolant I flushed the system with a white vinegar/water mix, then flushed again with water to clear it out. The old coolant was nasty and clearly hadn't been changed in many years. There were some brownish solids that could have been a stop-leak product, or just accumulated gunk from years of neglect.

I know a pressure test of the cooling system is the right answer. To do it I would need to buy or build a test rig. I suppose a leakdown test could work as well - again, need to buy a tester. I'm wondering if I should just retorque the head bolts before I go nuts buying more tools. Any thoughts on retorquing stretch bolts?

How likely do you think it is that the head gasket is breached? If it is, parts are available, though I don't relish more heavy work on a car I thought I was ready to put on the road. Anyone had the pleasure of tackling a head gasket on a Saab C900 before?

In my professional opinion, the only way to test for a head gasket leak is to wait for the symptoms to get obvious.  A leak down test will show you a leak into coolant if its already so bad you can see the antifreeze running out the tailpipe.  A pressure test will push enough moisture into a cylinder to create a misfire on startup, but only after its been missing on startup already.

Park it hot, wait until the next morning, fire it up.  If you have a misfire for a few seconds and can smell burnt coolant out the tailpipe, you have trouble.  If not, you may still have trouble, but you can't tell. 

I'd drive the thing for a week or two to get all the little air pockets out of everything and to dry up the condensation in the pipes.  Then see if you have any unexplained coolant loss, or misfires on startup.

Find someone with a color change type tester that samples the air/fumes above the coolant in the header tank. This test is the only one that picks up a small leak. Otherwise Streetwise has it all down regarding leakdown test etc.

My basic plan was "drive it and hope for the best," so that's what I will do for the moment. I'm just getting it on the road tomorrow, so I'll give it a week or two of use and see how things settle out (or get worse). Given all the work I've done I'm going to be checking everything after every drive anyway, so I'll keep an eye on the coolant level and see where things are.

autozone has a pressure checker in their loan a tool program. I paid deposit and kept the tool.

If you do a head gasket , zip tie the chain to the gears, before you remove the chain tightening device. it is a pain but will help with reassembly.  

Yep, I'll keep the chain secured - no reason to make things more difficult than they need to be. Having looked at the procedure on this motor it seems pretty straightforward. I've done head gaskets before, but this engine is new to me - hopefully there are no unpleasant surprises.

In reply to 02Pilot :

What year is it? I recall the early turbo 900’s & 99’s had some head issues(cracking?).

It's a 1989 NA 16v, which from what I've been able to discern shouldn't be particularly susceptible - it's a 2.0, not the later 2.1 that was prone to HG failure. I looked for info on cracked heads, just to prepare myself if it was a known issue on these motors, and I couldn't find anything.