alright so its a 1995 gt auto, i put a 180 Tstat in it. my question is, half the time the car will set at 185 and then all of a sudden, it will shoot up to around 205-210. then, after no certain amount of time(sometimes a couple of minutes, or sometimes 10 or so minutes) it will go back down to around 190 fairly quickly.the radiator is full of coolant(50/50). you can drive it for a while and does fine, then when it wants the temps go up, and then at random times, goes back down.
ya the Tstat is in correctly and i used a gasket facing correctly. I did get a 563 code(high fan control circuit failure ) when i pulled codes. what could/can cause that code to show??? i did notice when the temp was up around 205, the fan was not coming on. also, what temps do the low, and high speeds supposed to come on??
Air pockets possably? How long ago did you put the new thermostat in?
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1988 Mustang GT
Pypes Violator Cat Back
BBK Cold Air Intake
Underdrive Pulleys
The Original Ash Tray Lid
Thats It And Thats How Its Going To Stay , for now.
You might want to consider checking the temp sensor located on top of the T stat on the manifold. Also, to test the fan, turn on the A/C, you will then notice the fan quickly go into high speed, if not the fan is the problem... Good luck, hope this helps!
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the temp gauge is mechanical and i replaced the coolant temp sensor on the left side of the dist.(the one for the ECM to get the temp) the fan comes on when i turn the A/C on, any more ideas?
the temp gauge is mechanical and i replaced the coolant temp sensor on the left side of the dist.(the one for the ECM to get the temp) the fan comes on when i turn the A/C on, any more ideas?
Haynes repair manual recomendations:
1. insufficent coolant in system
2. drivebelt defective or not adjusted properly.
3. radiator core blocked or radiator grille durty and restricted.
4. Thermostat faulty.
5. cooling fan not working properly.
6. Radiator cap not maintaining proper pressure.
7. ignition time incorrect
8. defective water pump.
9. improper grade of engine oil.
10. innacurate temperatyre gauges.
have all this check,
also some additional information, according to Haynes: the CCRM turn the fan on at low speed when coolant temperature reachs 221 degrre F and turn the fan off when the temperature lowers to 200 degrees. the High speed portion off the fan only operates when the engine is hot and the ac is ON.
so doing some analysis what is happening may be that:
you turn the engine on it reachs 180 very quicly because the Tstat is closed after that it kinnd of stabilize but keep increasing at lower speed because you got water circulating (because tstat is now open) when it reach 221 the fan turns ON at low spped and pull the temp down untill it gets under 200, then the fan turn off and it start increasing the temp again and the engine keeps in this loop, I see that as normal behaivor, because if you only changed the tstat you can not hope that the engine is going to run cooler, it may but it may not too depending on your complet system.
one quick test you can do is to connect the low speed portion of the fan directly to the batery by a relay controlled by the swicth, so it turn on as soon as you turn the key to ON position, since the fan is going to be on all the time, the engine should increased the temp until 180 when the tstat gets open and temp should not increase any more because the fan is always ON and if the temp goes below 180 the tstat will close keeping the temp at 180. if that is the case your system is running OK and you are sppecting more from it without making the correct changes.
also, you can pay atention to the fan vehaivor, if the fan is always Off when you see teh temp increasing and it is always On when you see the temp decreasing, again your system is working correctly and you should make additional changes to keep it runing cooler, like install a different fan controller system.
hope this help
first off, thanks for the detailed help. today i was driving and i would switch the high speed fan on and it would sit around 200ish. being a 105 degrees out i dont think thats to bad. seeing how the fans are set up to work i think the ecm wants the engine to run around 200 degrees, give or take 10 degrees. im going to try to do a little more work on the cooling system and ill let ya know how it turns out. thanks again
quick question, I'm also having problems with my cooling fan and was wondering if you can kindly let me know how to test my high speed? My fan turns on when I turn on my AC but I seems to be on low speed instead. thanks a lot.
no problem friend. the easiest way i know to check the high speed fan it to get the car at operating temp, and turn your a/c on high and max AC. your high fan should come on automatically. your high speed comes on at two points, one being when you turn your ac on, and the second is when the coolant temp gets to 220. you should also check your fuse box under the hood because you have a couple fuses and relays that are related to your fan working. hope this helps ya. let us know what ya find.if you have any more questions, just ask
1995 Mustang GT, yet another cooling issue 
, for now.
