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'91 w/305 Getting to hot

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  #1  
Old 08-22-2011, 07:02 PM
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Default '91 w/305 Getting to hot

Hi all. Have a wierd problem I was hoping someone could help me out with here.


From the day I picked up my car, about 14 years ago with 18,000 mi, the car never had a heat issue. After starting the car in the morning, it would take about 10 min, and the temp would get up just slight bit over 220F, and then come down to a bit under 220, where it sit for the duration of my ride. It would go up a bit, down a bit, depending on if I was on the highway, temp outside, etc. But it would run at just under 220, give or take, always. Until a couple of months ago. Now, it starts off the same way - gets up just slight bit over 220F, and then comes down to a bit under 220, and sits there, but only for about 40-45 min. After that, the temp starts to rise, and rise and rise, if I am driving locally....If I am on the highway, it doesn't go over 220, b/c I am getting enough airflow. But if I drive locally, it does. But again, it's fine - even locally - for the first 40 min. or so, and then the problem starts.

I was due for an antifreeze change, so I changed it, and it seems to have helped slightly, but the problem still remains. Now, the fact that it curently gets up just slight bit over 220F, and then comes down to a bit under 220, and sits there for quite a while, indicates that something is working right there. Then there is the fan situation. The fan does not come on like it's supposed to, but seeing as tho it's electric, it does come on when I put the a/c on. So, one idea I had is that the a/c being on is causing the problem (is that possible?), but i can't turn it off, b/c then the fan goes off, and then the car gets too hot anyway, rendering that exercise pointless.

Any ideas here as to where I should look? Thank so much!
 
  #2  
Old 08-22-2011, 09:05 PM
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When you are on the highway how far does your temp come down?

What thermostat is in it?

Do you have a duel fan, or single fan?
 
  #3  
Old 08-22-2011, 09:47 PM
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If the fan is not turning on by itself but works fine if the a/c is turned on, change the temperature switch for the fan. Its on the passenger side of the engine block, if you plan on changing it yourself, you'll need to access it from under the car
 
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Old 08-23-2011, 01:46 AM
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I just changed mine. Not very difficult either. I changed my connector also. It cracked like an egg shell when I removed it. I bought a replacement from NAPA for about 13.00. The temp comes on earlier than before maybe due to a better connection.
 
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Old 08-23-2011, 10:28 AM
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any other issues with the car? is the coolant level going down? could be the fan is wearing out. how many miles are on the car now? have you ever cleaned the radiator? being the car is a bottom feeder, its very easy for the condenser and radiator to get clogged with debri. even if it looks clean, blow it out with air from the engine side. if you can, loosen the condenser and remove any debri from there
 
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Old 08-23-2011, 10:59 AM
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Originally Posted by microkid
any other issues with the car? is the coolant level going down? could be the fan is wearing out. how many miles are on the car now? have you ever cleaned the radiator? being the car is a bottom feeder, its very easy for the condenser and radiator to get clogged with debri. even if it looks clean, blow it out with air from the engine side. if you can, loosen the condenser and remove any debri from there
Bottom feeder??? I cleaned out the between condenser/radiator just a while back. I's running nice and cool. I flushed the cooling system out in spring, and it has 152,000 miles on it, and runs like new. The only trouble I had was the sensor, and bad connection. In fact I am not convinced the switch was the culprit, but the connection, but I'm not about to install the old one to settle my curiosity.
 
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Old 08-24-2011, 08:13 AM
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Check if the AIR Dam is still in place ubder the car. Sounds like that may be your problem with overheating (boken or missing air dam).
 
  #8  
Old 08-24-2011, 08:32 AM
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Originally Posted by Stevolwevol
Bottom feeder??? I cleaned out the between condenser/radiator just a while back. I's running nice and cool. I flushed the cooling system out in spring, and it has 152,000 miles on it, and runs like new. The only trouble I had was the sensor, and bad connection. In fact I am not convinced the switch was the culprit, but the connection, but I'm not about to install the old one to settle my curiosity.
I thought I was on a different thread. Never mind this.
 
  #9  
Old 08-30-2011, 10:41 PM
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Hi - many thanks for the replies.

To answer some of the questions:

When I am on the highway the temp comes down to a bit under 220, maybe 200-205?

What thermostat is in it? - no idea

I have a single fan.

No other issues with the car. Save for the passenger side window not going down, but obviously...

There are 136,000 mi on the car. All orig.

No, I have never cleaned the radiator - how does one do that? I flushed it with some clean water before I put the new coolant in...is there another step to take?

The air dam is still in tact.

As for the fan temp switch - got under the car, but could not find anything on the passenger side of the engine block. But do we really think that will help the current situation? Sure, it might help with the fan not coming on right away, but right now I really wish to get the overheating situtation out of the way. And the overheating does happen with the fan on, so I don't think that fixing that switch right nwo will help - right? I looked in my Hanes manual for fan temp switch replacement, but couldn't find anything.

As for cleaning the compressor - it looks pretty clean, relatively speaking. I can post a pic or two if necessary.

Also - there is something else I thought of just yesterday - my cat. Is it possible that an old/bad cat could be causing this issue? I am almost positive that I need a new one, and was thinking that if the cat is bad, then maybe that can cause overheating after a while?

Thanks guys for the time - hope to get to the bottom of this soon.
 
  #10  
Old 09-28-2011, 12:06 PM
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I am surprised that nobody mentioned the thermostat. They do go bad.... And with 130K..Probably time for a change. I had a simliar problem with mine when I bought it around 135K 6 years ago.

In 91 they were still fighting the emissions war with the EPA. these cars were built to run hot. (not that that is a good thing) But Thermostats can wear faster on hotter engines.

I would recomend replacing the thermostat and thermostat gasket. 30-40 buck and your back on the road in 2 or so hours. If that don't work at least its eliminated.
 



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