Here''s my dilemma:


I bought a used SL2 98'' with 180Kmiles. It works fine except the heat didn''t work, so I changed the thermostat. First I flushed the old fluid(which looked like dex-cool), ran the car without a thermostat for 5 minutes with just water to get the gunk outta the water pump, installed new Stant 195 degree thermostat and filled with 50/50 dex-cool (Prestone). Prior to this I never had an issue, but now when I drive about 15-20 miles on the highway my coolant light comes on. At first it worried me, and I''d pull over and fill it. Funny thing is is that there wasn''t any pressure under the cap. After a while, I realized that it boils over a certain amount then stops (usually about a .5-1 quart. I replaced the resevoir cap and it still does this. I usually have the heat on so it doesn''t overheat (usually stays b/w 1/4 and halfway mark.). Once I turned the heat off and it began to rise over the halfway mark so I turned the heat back on. I replaced the resevoir cap and the radiator hose that goes into thermostat housing. I don''t think ti''s a headgasket cuz my oil isn''t milky. I heard Stant thermostats were good, even on saturns. I don''t know what to check.

 

I assume that you are filling the resevoir properly (just to the line) and not all the way up ...

 

yeah, I fill it up to the max line. I see coolant beading on oil pan so I know I have a leak somewhere. I typically lose about a pint to a quart every 50 miles. Someone on another forum said the new t-stat I put in is prolly faulty so get a new OEM one. I felt my 2 radiator hoses. The inlet was hot and the outlet was cool. I know this isn''t a sure fire test but doesn''t this tell me that the coolant is circulating thus the t-stat is opening. One more thing, my car is only losing coolant not overheating. It doesn''t get past halfway on the coolant temp gauge because I always have the heat on.First things first, I have to find the leak.