dmoss90660 Posted December 4, 2011 Share Posted December 4, 2011 I've got a 2007 Fusion with 45,000 miles on it. I did a coolant flush last September, but I did not flush the heater core. Now that winter has arrived, I find that the heater is always cold, and I regularly get the P138 coolant under temperature code. I figured it was a stuck thermostat, so I just replaced it (plenty of fun! turns out the thermostat certainly needed replacing). I was hoping to have a victory lap, but all I really have is more confusion. There aren't any leaks and the coolant reservoir is filled up to the cold level. With the heater off, I went for a 50 minute drive with my scanner plugged into the OBD port. Prior to the drive, I let the car idle about 20 minutes and the coolant temperature was 230 degrees. Once I went out for the evening jaunt, it was 21 degrees outside and the coolant temperature was all over the place. My speed was 35 mph (except the few red lights I had to stop at), yet the coolant temperature was fluctuating wildly. One moment it would be holding steady at 234, then suddenly jump up to 259 (it looked scary on the temperature gauge--clear up at H!), yet continuing to drive at 35 mph for about 3 minutes and the temperature dropped to 219. Driving on a long stretch of highway with no stops going 35 mph, the temperature would again vary between 234 and 259. The few times I turned the heater on it was very cold (although not as cold as turning the temperature control all cold). Now the really weird part. Driving home I decided to leave the heater on to see if it would make any difference. The coolant temperatures now varied between 219 and 240. Yet any time my rpms were over 2000, the heat was warm. If I was under 2000 rpms, there was no heat. If the parking brake is on and car is in neutral at 2000 rpms the heat is still cold; if I take the parking brake off leaving the engine rpms at 2000, the heat is warm. Driving down the road produces heat if the rpms are 2000 or higher. I'm thinking the problem now might be a clogged heater core that I will need to flush. Does that sound like a valid diagnosis? Any other ideas? 0 Quote Link to comment Share on other sites More sharing options...
FusionDiffusion Posted December 4, 2011 Share Posted December 4, 2011 Whoa, anything over 220-230°F is overheating in my book. The water temps should be 190-220° normally. It sounds like you have a lot of air in the system still. Did you open the bleed valve and get all the air out? Also, are you sure you didn't install the thermostat backwards? Also, are the radiator fans working? They should have been going full blast at those temperatures. I hope you didn't damage your engine doing this. Anytime the needle is approaching the red zone you need to pull over, turn the engine off, and let it cool. Now some of the higher temps you registered might have been steam pockets, but if you have those your engine isn't happy at all (it means there are hot zones without any coolant)! You need to properly fill and bleed the system before you drive anywhere to prevent further engine damage. I would be way more concerned with getting a stable coolant temp before even thinking about heat. If you get the system operating properly and you still don't have any heat, I would then flush or replace the heater core. 0 Quote Link to comment Share on other sites More sharing options...
dmoss90660 Posted December 5, 2011 Author Share Posted December 5, 2011 Whoa, anything over 220-230°F is overheating in my book. The water temps should be 190-220° normally. It sounds like you have a lot of air in the system still. Did you open the bleed valve and get all the air out? Also, are you sure you didn't install the thermostat backwards? Also, are the radiator fans working? They should have been going full blast at those temperatures. I hope you didn't damage your engine doing this. Anytime the needle is approaching the red zone you need to pull over, turn the engine off, and let it cool. Now some of the higher temps you registered might have been steam pockets, but if you have those your engine isn't happy at all (it means there are hot zones without any coolant)! You need to properly fill and bleed the system before you drive anywhere to prevent further engine damage. I would be way more concerned with getting a stable coolant temp before even thinking about heat. If you get the system operating properly and you still don't have any heat, I would then flush or replace the heater core. Although I did open the bleed valve, there must have been air in the system since this morning as I checked on the car it was low on antifreeze. No sign of leaking underneath the car or around the thermostat, so it must have been air. I refilled it, again making sure to open the bleed valve, and went for another drive. The temperature was stable and varied between 190 and 212 and produced plenty of heat. Thanks for the suggestion! 0 Quote Link to comment Share on other sites More sharing options...
FusionDiffusion Posted December 5, 2011 Share Posted December 5, 2011 Good, I'm glad to hear you got it all taken care of. Air in cooling systems can be tricky to get rid of. Keep an eye on the coolant level for the next few days and then every few weeks to make sure. 0 Quote Link to comment Share on other sites More sharing options...
TanK203 Posted January 3, 2012 Share Posted January 3, 2012 Quick slightly off topic question. I'm planning on doing a coolant flush myself, and was curious if the bleeder valve really needed to be open. I read in another post that if you just let the engine run for a while with the radiator cap off, it would get rid of all the air. Thanks for your help. 0 Quote Link to comment Share on other sites More sharing options...
akirby Posted January 3, 2012 Share Posted January 3, 2012 Quick slightly off topic question. I'm planning on doing a coolant flush myself, and was curious if the bleeder valve really needed to be open. I read in another post that if you just let the engine run for a while with the radiator cap off, it would get rid of all the air. Thanks for your help. If the bleed valve wasn't necessary, why would they put one in? 0 Quote Link to comment Share on other sites More sharing options...
FusionDiffusion Posted January 3, 2012 Share Posted January 3, 2012 Some of the Fusion engines have them, and some of them don't. Fill up the radiator and coolant bottle first. With the system open, run the engine until the thermostat opens and you see coolant flowing in the radiator. Turn the heater on full hot. Top everything off and open the bleeder valve(s) until solid coolant runs out. Rev the engine to about 2500-3000 for a few seconds, and then repeat the previous step. Keep doing it until you don't have to add any more coolant. Put the caps back on and go for a short drive. Bring the bottle of coolant with just in case. Keep a close eye on the temp gauge. If it's getting near the red region, you need to pull over immediately. After the drive, let the engine cool for about an hour and carefully open the caps with a thick cloth. Confirm/top off the coolant level. Follow these steps and you shouldn't have any problems. Many people forget to run the car until the thermostat opens and end up with an empty block. Remember to use a 50/50 mix unless you live in an extremely cold (northern Canada) or extremely hot climate (Arizona desert). Only adust the mix a maximum of 10% ( so 60/40 or 40/60). Also, use only distiller water to mix coolant. The minerals in tap water will accelerate engine corrosion. Finally avoid using Prestone unless you car has orange coolant. It is not comparable with the green or yellow coolant systems despite their false claims on the bottle. The Fusions use three different types of coolant, so be sure you put the right stuff in. The dark green coolant is not the same as the older lime green stuff. 0 Quote Link to comment Share on other sites More sharing options...
Dyoct Posted January 7, 2012 Share Posted January 7, 2012 (edited) Did any warning lights ever come during the higher temps? At 260 the vehicle should go into fail safe mode where the engine light will flash, the oil light will come on and the vehicle will have no power as the fuel injectors alternate cylinder shut off to pump air through the block. It sounds like you had major air pockets in the system. That bleed valve has to be opened ANYTIME you add more than a quart of coolant/water. AND ONLY OPEN WHEN COLD otherwise it's like opening up a radiator cap under heat/pressure! IIRC I think only the 4 cylinders have the bleed valve, the V6s do not. Edited January 7, 2012 by Dyoct 0 Quote Link to comment Share on other sites More sharing options...
tcbouma24 Posted April 15, 2012 Share Posted April 15, 2012 I just replaced the Thermostat in my 07 4cyl. fusion and are having similar issues. sorry if I'm stupid here, but where is the bleed valve?? The haynes manual doesnt say anything about it? Thanks!! 0 Quote Link to comment Share on other sites More sharing options...
FusionDiffusion Posted April 15, 2012 Share Posted April 15, 2012 Your owner's manual does. It's near the battery. Read your manual for pictures and instructions. 0 Quote Link to comment Share on other sites More sharing options...
twiggy144 Posted April 15, 2012 Share Posted April 15, 2012 I have a clue why Ford put a bleeder valve. On my daughter's Mazda3, for flushing and refilling the system, the manual reads to run the engine at 2500 rpm for 3 min , twice, idle in between the 2 runs, then run at 3000 rpm for 5 sec, then idle again, then repeat whole procedure. When I flushed the system, I noticed it takes much time to get all the trapped air circulate out of the system, (and exit to the reserve tank). Until the air is all out, the heater core does not get hot fluid like it should. Mazda did not put a bleeder valve on the system, like Ford did. The bleeder valve, smartly installed at one of the highest points in the system, helps considerably remove the air pockets oiut of the system. 0 Quote Link to comment Share on other sites More sharing options...
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