Hi Scotty. 99 Mercury Sable. 3.0 V6 U Vulcan engine. 102k...ish miles. Had vibration coolant flush done at Firestone in Conroe (at least they said they did) 3K miles ago. Didn't try heater until 2 wks ago when it got cold. NO HEAT! I did a flush today. Took off heater core hoses and pinched off bypass hose. Flushed out core back and forth 20 times until totally clear with garden hose. Then did entire engine/radiator flush back and forth 6 times until totally clear as directed on Scotty's YouTube video. The core flush was VERY NASTY!!! SOOO much "gunk" came out. There is NO way they did the flush or at least did it properly. Thinking I probably got scammed. Called them, they gave excuses of course w/no warranty. Anyway, when I did the final drain (all hoses hooked up, just opened radiator plug) it only took 8 quarts of antifreeze. Specs say 11.7 quarts. Was there still possibly 4 quarts in the engine that didn't drain? Will it be ok if it's 2/3 50/50 antifreeze and 1/3 water? I test drove it and heat was great and engine temp is good. Turned it to cold drove a while, turned heat control to max and saw engine temp drop slightly, as it should, then rise back up to normal. Cooled off engine, checked fluid level and it's still at full.
Try this method of filling your radiator. Jack up the right front wheel and let the engine run...More than likely you have a air pocket so thats why your heater works then it doesn't. Run the car with cap off and hopefully the coolant or water will fill the void and the level will go down. Fill the radiator some more till its totally full or sometimes the coolant attempts to spill out. Cap it and test the heater inside or you can feel the heater hoses. They both should feel hot..ok one a little more than the other but you get the idea. Let it idle and let it get hot...fan should come on..go for a test drive and see if your temp should not waver if the thermostat is working right.. Speaking of which..original thermostate? Should change it before it malfunctions because of old age.
You misunderstood I think. The heater works great. I mentioned that I drove it with temp control turned to cold then to hot. I did that to make sure everything was working well. It does. My Only question is why the it only took 8 quarts. I will try the right side up thing to see if air migrates to the top.
Also, I haven't changed thermostat and don't know when/if it's been done. I checked the service records. Previous owner kept them. Don't see it was ever done. The temp gauge variation I spoke of was VERY slight when I moved control from cold to hot. I know on older vehicles when the uncirculated cooler fluid from the core leaves, if you haven't used the heater, when turned to heat it runs through the system bringing the engine temp down just slightly then rises. It's like on older vehicles you used to be able to watch the temp gauge change a very little when the thermostat would open and close.
Do change that thermostate as it could fail as you can't verify its age. Looks like you just about got it under control - Good Luck!
I always pour in concentrated antifreeze to make sure it all gets in there. Some water always gets hung up inside. Then I top off with water as needed.
Your coolant concentration is now 33% antifreeze to 66% water. It will resist freezing to around -12C/+10F
