Date: Fri, 14 Jul 2000 22:04:03 +0200
From: Robert Brown <rjbnopsamnetNOSPAM.se>
Subject: Re: Themostat Swap


OK, good to hear it. But be sure to check the electric fan thermostat (and the fan), if the fan's not coming on when the engine gets hot. This "3/4" reading on the temp gauge is a lot higher than I ever get, which is why I'm wondering. On my car the temp gauge rises to about 15 degrees of angle above the horizontal before the fan comes on. Short across the fan thermostat terminals as I mentioned in the last posting (I've been fanatical about this since I cracked a head due to bad fan) Glad to hear you chose a 1985 900 as your first car. Lots of fun and relatively uncomplicated to work on. Just make sure you keep the underbody well protected from salt (lots of tar-like things you can paint on. Also keep the frame under the drive shafts rust-free and you'll have a car that should give you some years of good motoring. Regards, Robert (1983 900) saabsternopsameja.com wrote: > Went ahead with the thermostat swap, using a 180 degree thermo rather > than a stock 192 degree one. Everything is a-ok. Been driving on the > highway and the temp gauge stays consistently just below halfway, > although during idling and stop-and-go city driving it can get up to > 3/4 before going down to normal. No evidence of a cylinder head crack > or a head gasket rupture--thank God!--but after I swapped the thermo I > drove it around for a day and by the end of the day my gauge was, for > lack of a better term, tweaking--i.e., jumping up and down rapidly. I > opened up the old Haynes book and found it to be a severance of the > wire leading to the temp. gauge transmitter; a little electrical tape > provided a temporary fix. > > Thanks for the advice, though. This is my first car and three weeks ago > I knew zero about auto mechanics, so I must say I'm proud of my little > D.I.Y. repair jobs. > > Saabster 85 900 > > In article <396E1A9E.2DD5E6EDnopsamnetNOSPAM.se>, > robert.brownnopsamnetNOSPAM.se wrote: > > Hi, > > > > Changing a suspect (sticking?) coolant thermostat is where I'd start, > too. > > But if you have trouble finding the radiator drain plug you can > detach one > > of the radiator hoses instead. Or you can simply remove the bolts for > the > > water thermostat housing and lose a minimal amount of coolant that > way (just > > be sure that the coolant's not too hot and the expansion tank cap's > loosened > > to relieve pressure, otherwise you get it all in your face, as I > found out > > once ;-) No big deal with the coolant in the engine bay, just hose it > down > > afterwards so you don't get paint damage. > > > > As far as the bolts on the thermostat housing are concerned, just do > them up > > tightly and evenly enough so that nothing leaks (ya don't have to do > them up > > monster-tight). The rubber seal around the thermostat is supposed to > take > > care of possible leakages. > > > > You can safely remove the thermostat (or rather tear out the active > bits in > > the middle and retain the outer metal that holds the rubber gasket in > shape > > in the housing). The disadvantage is of course running the engine too > cold > > wintertime (bad fuel economy but that's about all). > > > > There are also thermostats that activate (i.e. open) at a lower > temperature > > but I have no experience of these so I'll let the other NG > contributors > > address that one. > > > > Another trick you can use to lower the temperature a fraction is to > put the > > cabin heat on full and run the cabin fan. This will dissipate engine > heat > > through the cabin heater matrix but you'll want to open your windows > after > > that one. > > > > Something strange about you having such a high "driving-around" > temperature, > > yet seeing the temp gauge go down when you're at the lights. That's > the kind > > of behaviour I got when my head cracked (that sure as hell cost me a > few > > hours' work) a few years ago. Without speculating further about the > above > > temperature change, here's a list of some things to check for when > you're > > getting overheating in general: > > > > 1. Sticking coolant thermostat, preventing coolant from reaching the > > radiator in sufficient volume (you're already addressing this one). In > > Sweden these cost about USD 10.00. > > > > 2. Electric fan thermostat (screwed into the radiator, find two > wires) or > > electric fan may be broken. Does your electric fan come on every once > in a > > while when the motor's hot? Test by shorting across the thermostat > terminals > > to see if at least the electic fan comes on. > > > > 3. Rotting cooling fins in the radiator itself (corroded metal does > not > > dissipate heat well) > > > > 4. Garbage in the radiator (leaves, etc) > > > > 5. Partial blockage of coolant channels in radiator or engine block > (if so, > > you'll have to flush and reverse flush radiator and engine block) > > > > 6. Rupture of head gasket or crack in cylinder head. Symptoms of this > > include frothy oil on dipstick, coolant coming out the exhaust pipe > (don't > > confuse this with the normally small amounts of water that leave the > pipe > > due to normal combustion), engine missing on one or more cylinders > when > > starting cold, bubbling coolant due to exhaust gases entering cooling > system > > (can cause the expansion tank to rupture). These cases will also > cause the > > coolant to have a higher than normal temperature. > > > > 7. What have I forgotten? > > > > But check the first 5 points before seeking professional help on > point 6. > > Any garage would love to tell you you need a new cylinder head and > get you > > to pay for that . . . > > > > Under normal driving conditions and a wide temperature range (-5C to > +25C) I > > find that my temp gauge in my 1983 900 GL (8v no turbo single carb) > stays > > consistently at the half-way mark. I have a new coolant thermostat, > newish > > radiator, flushed everything etc. Not sure what a few degrees extra > would do > > but I doubt that I'd be up to 3/4 on the temp gauge, as you are. > > > > I hope your problem is easy and cheap to fix. Tell us all how things > turn > > out. > > > > Robert > > Gothenburg > > 1983 900 GL > > 1999 9-3 200 > > 1983 99 GL (r.i.p.) > > > > saabsternopsameja.com wrote: > > > > > When I came into Denver from Salt Lake City, I found the mountains > just > > > of Denver to be pretty hairy. Just to maintain 60km/h (about 35mph) > I > > > was in second gear and 4000rpm. The temp gague never did get past > 3/4, > > > so I assumed everything was ok. > > > > > > I parked the car downtown and explored Larimer Square and the > historic > > > district for about half an hour, and when I came back there was a > > > massive pool of coolant on the street next to my ride. Naturally I > was > > > freaked, but was somewhat relieved to discover that the rad had no > > > holes, the hoses were kosher, and that the fluid had leaked from > under > > > the expansion tank cap, which had a busted gasket. The next morning > I > > > went to the Mike Shaw Saab dealer on Colorado Blvd. to get a new > cap, > > > put it on, and in the days following the car was running a bit hot > still > > > but no longer leaking. (The temp gauge would get as high as 3/4.) > > > > > > Now the weather in Denver has this week been hot, like 90-95degrees > > > (32-35celsius). I thought that might be the problem, but I went and > > > bought a new themostat anyway. But it seems putting the thing on is > > > going to be tougher than I had thought. For one, I can't figure out > how > > > to drain the radiator, since the crappy Haynes manual only says the > > > drain plug is "on the right-hand side" and gives no photo or > drawing. > > > I've been told, though, that I can just take off the thermostat > housing > > > without first draining the system, but I don't want coolant > spilling all > > > over my engine compartment. Another thing (though this isn't a huge > > > deal) is the fact that I don't have a torque wrench, and the bolts > on > > > the themostat housing are supposed to be tightened to a certain > torque. > > > Does it really matter all that much if it's not exact? > > > > > > I'm not sure I even need to change my thermostat at all. Driving > around > > > the city the gauge gets up to 3/4; then when I pull up to a stop > light > > > it'll go down to below halfway. That, to me, would indicate that my > > > current thermostat is working peachy. > > > > > > Then I had some advice from this one fellow who recommened my > removing > > > the thermostat altogheter during summer--especially since I'm going > into > > > the heat belt of America after Denver (New Mexico, Texas, > Louisiana). > > > > > > I'd like some advice here, fellow Saabsters. I'd hate to be stuck > out in > > > some Texas backwater with an overheated engine. > > > > > > Saabster 85 900 8v > > > > > > Sent via Deja.com http://www.deja.com/ > > > Before you buy. > > > > > > Sent via Deja.com http://www.deja.com/ > Before you buy.

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