Help me diagnose this cooling problem.

syphon

Registered User
So I belive my thermostat may be stuck open, but I dont know enough about the subjec to be able to tell for sure. Here are the symptoms

-Car stays cold for a very long time. It takes almost a half hour to warm up properly... even if I let it warm up in the driveway for 15 minutes it'll still knock for a while when I drive until it warms up.

-The temp never goes above C if I have the defroster on. Even with the fan on the lowest setting, if the heater is on the engine barely warms up. To prove it, here is a picture I took after driving home from work.
This is after about an hour in stop and go traffic on the freeway...
cold.jpg


In contrast, if I turn the heater completely off, it will warm up to normal temperature. Here is a pic I took after driving about 20 minutes with the heater off
warm.jpg


I know the temp guage works... because the heater air warms up right along with the guage. If the guage is below C... the heater blows barely warm air. If The guage is way up there, the air is nice and toasty.

Before you ask, Antifreeze is fine. As best I can tell, I haven't a coolant leak anywhere. In fact, havent touched the cooling system since i bought it a couple months ago other than checking the coolant level.

What do you guys think, is this a thermostat problem?
 
here are my thoughts

First I would have to ask what is the outside temp when you are driving? I assume it is cold if you are running the heater. Here is the other thing I would check. When you turn on you heat and even your A/C, does your radiator fan kick on. You said when you turn off your heater the temp goes up. If it is really cold out side and your fan is drawing in that cold air, your car will run nice and cool. Sounds to me like your fan does kick on and off when you turn on your heater. I believe your year of car only has one radiator fan, unlike my '94 which has two. When I am in stop and go traffic, and even when it is 60 outside, I turn my A/C on to get that fan to kick on to cool off the radiator, otherwise my temp will run really hot. Last but not least, it is a pain in the but, but go get a new thermostat and felpro gasket and put it in there and flush the radiator. Don't always go by those temp gauges, they sometimes are not that accurate. Good luck, and have an extra set of hands with you if you put a new thermostat in, you will need them.
 
Mine's doing something similar on the cold days, I'm sure it's not as cold as your seeing though. Still, it stays down pretty low unless I'm really on it stirring up some heat. I think the defroster uses the A/C, which does seem to bump up the fan and cool things off even more. I've got a new thermostat that I know works fine, so I'm not worried about it. Seems directly related to the outside temp, especially when I'm on the interstate and it's getting blown pretty good.
Other times I've seen this, but the needle goes totally dead has to do with the loose temp sensor wire.
 
Indeed the temperature is cold around here, but even spending up to an hour in stop & go traffic, it'll barely heat up.

Is a thermostat that hard to change? I've helped with my friends thermostat, but I'm only vaguely aware of where it even is on my car.
 
cooling problem.

I like all of the suggestions that I've read so far and would like to add a couple of thoughts. 1.) If the previous owner put in a very low t-stat, it could cause heating problems. So, when you do get a new one, I would get a factory t-stat from Ford b/c I noticed that they have a weep hole that most of the after market one didn't have. Plus when you install the Ford t-stat, you have to put it in and then turn it clockwise to lock it into position. 2.) I would also buy a new 16psi rad cap b/c if it is weak, it will not hold the pressure long enough for the rest of the system to work properly. I change mine every couple of years whether it needs it or not, I feel that its good insurance for $5 bucks. If you remove the rad cap and let the engine idle, do you notice the coolant flowing? Good luck
 
Either you are low enough on coolant that it isn't reaching the temperature sending unit in the thermostat housing (in which case the actual heat of the metal around it would cause it to read "C" without any coolant even making contact) OR, you thermostat is stuck open.

Both of these situations have happened with my SC before, and gave the same symptoms.
 
T-stat

I changed my t-stat to a 180, and it didnt twist in like the ford one, but i just assumed that it sat in there. I slaped it in and put the gasket on. Since then the temp gauge hardly ever goes above C. What gives, is this bad? what to do.
 
cooling problem.

I don't know if it is good or bad to have the after market 180deg t-stat, others will have better insight on the subject. I just didn't want to take the chance after I compared it to my factory original. And I read in the manual that it had to be turned to seat properly before you put the gasket on. The t-stat and axle nuts are 2 things that I don't take chances with and I always buy them from Ford. Good luck
 
Just a quick question... you tell me that when I have the defroster on, the fan is going. Is this also true with just the "Vent" going? I was really cold so I had the vent blowing hot air right on me, and I noticed the car warmed up further than it usually does (I usually drive around with it on defrost at all times)
 
The Radiator fan comes on with Floor/Defrost, Defrost, and AC/Max & AC settings. Your temp on the gauge should go down noticablely within about 5 min. from the time you turn it on. The Vent setting brings in outside air via the holes in the cowl under the windshield in front of the passengers side. The rad fan does not come on with Vent or Floor. Maybe when you had the Vent on, you also had the temp setting over on the Warmer setting which would blend warm air through the heater core as well. Try that with it set on the Cooler setting. If the rubber on the leading edge of the cowl is gone or there is a gap in it, heat from the engine will flow into the heater air intake.
 
After running it in the "cool" position, I've decided that you're right. It's just mixing some air in with the heater core to get the heat, and the fan isn't coming on.

One final question for you guys... Do you think it's damaging to the engine in any way if the engine always runs that cold?

I'm getting worried because my engine is starting to knock when cold... and it keeps knocking for a long time. That's probably completely seperate though.
 
diagnose this cooling problem.

I don't know if running cool will hirt the engine, you should start a new thread on that suject, same with the knock which you will need to try to isolate because it could be on top or bottom. good luck
 
Some tips.

Hey there.

Yes, running colder than normal is not good for the engine.
You'll have more wear on the bearings etc. because the
engine is designed to run at a certain temp. At a lower temp,
the metal is stil somewhat contracted causing tighter clearances
on everything. And your gas mileage could be affected too.
Something to do with the fuel/air mixture temperature.

What I do on my '90 SC is place a piece of cardboard in front
of the radiator, just behind the front cross-frame, this keeps
the air from flowing through the rad causeing lower temps.
Works real nice unless you get stuck in traffic then the temp
will rise too much. I also have an added switch to control
the fan manually if desired. If you do a lot of stop and go,
then maybe add cardboard to only half the rad.

j.
 
Son of a B. I am having the same problem, i really need an answer. I live in michigans upper pennsula where the sign outside my dorm window reads 4deg f. I thought it was a t-stat problem. I was going to replace mine, but its going to be difficult seing as how i dont have a garage or anything up here to do it in. Has anyone been able to "FIX" this problem, because a piece of cardboard is not a "fix."

PS. running an engine below temp causes excessive wear on the cyl. walls and can lead to piston slap. (i dont remember where i read this but it was in some book somewhere) If anyone has had any success id love to hear it.

==DZ==
 
t stat

If she stuck open ..you should be able to pop the rad cap off.. cold engine ..and see the flow going through the rad
if not then T stat is closed ...I like the heat feature of the AC.... heat in 2 minutes ..rather than the 20 min on -20C days ..but it kicks the Hispeed fan on and takes alot longer for the car to get to normal temp
 
Heh, I didn't realize this thread was still going.

I replaced my thermostat...
tstatengine.jpg

That is what I found. Replacing thermostat fixed it.
 
i wouldnt be supprised if mines blown up like that too. Guess its the perfect topper to the week from hell.

---thanks
-dz
 
Well it got up to 50 deg..so i ripped off my water neck...and what i found inside totally amazed me

1. The thermostat didnt have a gasket, they had made one out of rtv BLUE.
2. The thermostat was installed backwards.
3. The thermostat had slipped and left a gapeing hole at the top.

--DZ..
Ps

Auto Value had the thermostat in 180, 195. and had thecorrect gasket.
+ one container of rtv blue
-------
6.00
 
Danzajax said:
1. The thermostat didnt have a gasket, they had made one out of rtv BLUE.
2. The thermostat was installed backwards.
3. The thermostat had slipped and left a gapeing hole at the top.

Heh, I still think I win for finding the most messed up thermostat. (see above pic).

"Wow, so THIS is why it seemed like it was stuck open!"
 
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