Date: Tue, 19 Mar 2002 23:52:05 +0100 From: Robert Brown <rjbnopsamnet.nospam.se> Subject: Re: Saab head gasket?
Dale James wrote: > Has anyone out there ever replaced the head gasket on an older (1985) 900 > model? Is this something I want to try myself, or does the whole process > just suck? > > The car recently started overheating, and bleeding the cooling system at the > thermostat releases a lot of steam, but *no* coolant. It really feels like > a bad head gasket to me. > > Thanks, > --Dale I cracked a head on a 1983 99 GL (H-engine, same as your 900) about 10 years ago and found the head and gasket job to be quite doable. Just make very sure that you get the right gasket, since the wrong one can cause oil and coolant to mix. Before you pull the head off though, you maybe should look for the more typical signs of gasket or head damage. Steam at the front coolant bleed valve isn't one of those symptoms IMNSHO. Save yourself a headache by checking the following (unless you've tried these already): I *would* believe in a gasket breach, however, if I found one or more of a) carbon monoxide in the coolant - repair shops can test for that, b) white smoke and water leaving the exhaust pipe, c) loss of combustion on one or more cylinders due to coolant leaking in, preventing spark, d) brown froth on the oil dipstick, indicating contamination by coolant, e) an extreme surge of coolant and gases when removing the coolant filler cap (keep your face away from there). My best guesses are either 1) your radiator's cooling fins have corroded away to nothing, so you have overheating due to no heat dissipation [replace radiator], 2) too much crud in your cooling system, causing flow problems [reverse flush and change coolant], or 3) [less likely] a sticking thermostatic valve (in the same housing as that bleed valve you've found). They mostly stick *open* though, causing too low operating temps, especially in winter. Haven't heard of one sticking shut, but that might account for the overtemp. But as I said, very unlikely for it to stick shut. Replace thermostat if that's the problem, but make sure you release pressure first by removing coolant filler cap before loosening thermostat housing bolts (I learned the hard way by getting it all in my face - yuck . . .) Just occurred to me that cooling systems of 900s that haven't been properly bled of air, will release only steam through the bleed valve when it is first opened. When I used to change coolant, I'd start the engine, open the bleed valve, get about 30 seconds' steam, a few seconds of sputtering coolant/steam, then a small stream of coolant. At that point, I'd close the bleeder valve and stop the engine. You might get it to run a bit cooler with less air in the system too. Curious to know what you problem does turn out to be. Tell us won't you . . . Regards, Robert Gothenburg (2001 Audi A4, 1999 9-3, 1983 900 GL R.I.P, 1983 99 GL R.I.P.)
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