Overheating and don't know why

9

93-331-29psi

Member

Jul 20, 2004

157

0

17

NE North Carolina

Aug 2, 2004

#1

• Aug 2, 2004

• #1

Maybe you all can lend a helping hand. I recently acquired an 86 GT. I seem to be having an overheating issue. I replaced the stat with a 180 degree piece and put on a new radiator cap. That didn't seem to fix the issue as when I run it for more than 20 minutes at highway speeds and park it the radiator starts to steam and overflow the overflow container. The car is 100% stock with no mods and has the factory plastic fan. Could I be looking at a fan clutch problem or even a Water Pump problem? Ideas

 

mustangsquared

Founding Member

Jun 8, 2002

828

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16

new bern nc

Aug 2, 2004

#2

• Aug 2, 2004

• #2

I would flush the coolant system and replace the fluids (since you do not know when done last). I would then "turn the fan". Does it move back and forth easy? Especially when hot. If so then it is a bad fan clutch. Also check to make sure coolant system is holding the PSI (I think 86's are 16 PSI). If all that doesnt fix it then it is probably the pump.

 

9

93-331-29psi

Member

Jul 20, 2004

157

0

17

NE North Carolina

Aug 2, 2004

#3

• Aug 2, 2004

• #3

Flushing the coolant system is the first thing I did. I checked the fan and it does turn fairly easy when hot. The cap is a 16psi piece and the system is holding that with no problems. I guess this will be the next part replaced.

 

mustangsquared

Founding Member

Jun 8, 2002

828

1

16

new bern nc

Aug 2, 2004

#4

• Aug 2, 2004

• #4

Replace the fan clutch...seems it is not grabbing enough thus not pulling the CFM's.

 

C

click

New Member

Nov 13, 2003

142

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0

Aug 2, 2004

#5

• Aug 2, 2004

• #5

make sure there is no gap between the fan and the radiator

 

bln92cpe

New Member

Dec 15, 2003

158

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Los Angeles, CA

Aug 2, 2004

#6

• Aug 2, 2004

• #6

get a flex fan and a fluidyne radiator..Thats what i did and now the fan blows cold air and my hood ramains chill after driving it.

 

9

93-331-29psi

Member

Jul 20, 2004

157

0

17

NE North Carolina

Aug 2, 2004

#7

• Aug 2, 2004

• #7

Well Clutch fan has been replaced and the damn thing is still overheating. Guess the water pump is next unless there are other ideas.

 

3

351 82GT

Founding Member

Mar 19, 2002

430

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Aug 2, 2004

#8

• Aug 2, 2004

• #8

Screw getting a flex fan and the hell with the stock clutch fan. Go to the junkyard and get a taurus electric fan for $25.
I had trouble with overheating when it would idle for more than 10 min.
It would slowly climp to 220-230* until I got moving again.
Now, it will stay at 170* all day long at idle.

If it boils over when you park it, it sounds like you don't have enough anti-freeze to prevent it from boiling over.
My probem was that the stock fan couldn't pull enough air through the radiator at idle....but my GT has a worked 351w though.

 

9

93-331-29psi

Member

Jul 20, 2004

157

0

17

NE North Carolina

Aug 2, 2004

#9

• Aug 2, 2004

• #9

Well this is just a daily driver so I am not putting tons of cash into it. I need to get my 93 done. Anyhow I have a 70% antifreeze 30% water mixture. It can sit and idle and not overheat at all, or at least not over the period of an hour, but starting cold a 5 mile drive around the block and she climbs and overflows the overflow tank. I am going to flush it again and replace the water pump and s ee what that does.

 

T

tjm73

Founding Member

Aug 3, 2000

2,418

2

48

Rush, NY

Aug 2, 2004

#10

• Aug 2, 2004

• #10

Hmmmm.....bad clutch fan...maybe that's why I'm running at 200-220 all the time this season when I ran 180-190 for the last 3 years. At least I don't have boil over. I'll have to check it.

 

3

351 82GT

Founding Member

Mar 19, 2002

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Aug 2, 2004

#11

• Aug 2, 2004

• #11

If it overheats while driving then it's the radiator. If it overheats while at idle then it's the fan.
Since it doesn't overheat at idle then I doubt it's the water pump.

At this point, I would take the radiator to a shop and have it hot tanked. That will get out anything you might have possibly missed with the flush kit and absolutly rule out a bad radiator.
You don't have a bad head gasket do you? Check the oil dip stick and make sure it's not milky.

 

R

ratrapp

New Member

Apr 24, 2004

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buena vista,va

Aug 2, 2004

#12

• Aug 2, 2004

• #12

if a water pump doesn't solve your problem then you need to pressure test your cooling system and check for leaks.if it pass's ok then have your radiator flow tested,any decent radiator shop can do this.if you still have trouble then look at the headgaskets or a possible cracked head.

 

9

93-331-29psi

Member

Jul 20, 2004

157

0

17

NE North Carolina

Aug 2, 2004

#13

• Aug 2, 2004

• #13

Well I think I figured it out. There was an air bubble in the cooling system. I let it run for about 30 minutes with the cap off in the driveway and noticed the fluid level went down. Topped it off with water, put the cap on and gave it hell. No boiling over but the factory gauge runs on the high side of normal. I will have to get an after market gauge on it and see where I am for temperature. Thanks guys

 

M

Mhypertext

New Member

Aug 1, 2004

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Joplin MO

Aug 2, 2004

#14

• Aug 2, 2004

• #14

man i was reading the thread and going to say you had an air pocket

 

R

ratrapp

New Member

Apr 24, 2004

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buena vista,va

Aug 2, 2004

#15

• Aug 2, 2004

• #15

the one thing your overlooking is what caused the airpocket.air pockets don't form for no reason.air has to be entered into the system by someone opening the system up and not properly filling it or you have an internal leak such as a blown headgasket or cracked head or block.if your air pocket comes back in a few days then you better start worrying.

 

B

blk92stangg

New Member

Jan 30, 2004

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Hawaii

Aug 2, 2004

#16

• Aug 2, 2004

• #16

The air pocket was probably from when he flushed the system.

 

D

D347643

Banned

Jan 28, 2003

1,095

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portland, OR

Aug 3, 2004

#17

• Aug 3, 2004

• #17

351 82GT
"If it overheats while driving then it's the radiator. If it overheats while at idle then it's the fan."

isnt it the other way around? since the fan barely turns when at idle and its main use is for driving?

 

HISSIN50

"How long does it take to get help in here?

15 Year Member

Nov 29, 1999

31,179

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129

Aug 3, 2004

#18

• Aug 3, 2004

• #18

D347643 said:

351 82GT
"If it overheats while driving then it's the radiator. If it overheats while at idle then it's the fan."

isnt it the other way around? since the fan barely turns when at idle and its main use is for driving?

Click to expand...

nah, i think D is actually right. the thinking is this:
while driving (normally alikened to being on the highway), the air being forced through the coil from speed (not the fan) cools the radiator. but when stopped, the only means to force air through the coil is the fan.

you are right - it is a little counterintuitive - it seems that the fan spins slow at idle. this is where electrical fans really shine. but a clutch fan will spin enough for an idling motor (that is the way it is engineered - to flow enough CFM's at idle to cool the charge sufficiently in extreme conditions).

once one is travelling at ~25 MPH or so, the fan being on (even a Mark 8) is immaterial - the speed of the air hitting the radiator (or creating the cavity of low pressure behind the radiator, in some cases) is enough to create a nice 'gust' that is much more than what the fan could do.

 

D

D347643

Banned

Jan 28, 2003

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portland, OR

Aug 3, 2004

#19

• Aug 3, 2004

• #19

yeah haha im use to an electric fan and my old clutch fan was bad, my bad.

 

K

k12

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Jul 28, 2003

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Aug 3, 2004

#20

• Aug 3, 2004

• #20

Just an FYI, I was told by a mechanic once that a good way to see if your fan clutch is on the outs is to have a friend turn the car off when it is at full operating temp. Stand to the side of the car with the hood open and count the number of times the fan spins before stopping. More than 2-3 times, its shot.