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Car overheating after driving about 30 minutes

Tiny
JMANGANIELLO
  • MEMBER
  • 1994 PONTIAC GRAND AM
  • 2.4L
  • 6 CYL
  • FWD
  • MANUAL
  • 184,000 MILES
The car was behaving like it needed a new thermostat, running hot and overheating. I replaced the thermostat and let it idle for about 45 minutes and it never got hot. Then I drove I drove the car for about 15 - 20 minutes at highway speed and it never got hot. The next day, after driving for about 30 minutes, the car overheated. It cooled down, I added coolant to replace what was lost and let it idle again for about 30-35 minutes. It never got hot. But after driving it for about 30 minutes, the temp shot up and it overheated, again. I went through the same drill and it doesn't overheat when idling, even for long periods of time, but after driving for about 30 minutes, it overheats. The heater works, and blows hot air so I don;t think it's the pump. What does this sound like?
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Thursday, December 12th, 2013 AT 6:47 PM

7 Replies

Tiny
TY ANDERSON
  • MECHANIC
  • 719 POSTS
You said your adding more coolant. Is there any leaks? Or is it boiling over?

When the engine is at operating temperature feel the radiator hoses and heater hoses for temperature differences. Is there any hoses colder than others?

If there are no leaks and you removed all the air in the cooling system (from the repairs) then the only thing left is a blown head gasket. Any air in the cooling system or loss of pressure (IE radiator cap) will lower the boiling point and cause overheating.

There is a test that uses a chemical reaction to determine combustion gases inside the cooling system and thus meaning a leak from the combustion chamber(s) into the cooling system (this is more rare but could include a cracked cylinder head or engine block).
The only name for this test I know is a "block chek" tester this test will tell you whether you have a major engine component failure or not.
Please answer my questions so I can narrow down the possibilities. I could be something simple as a radiator cap that is no longer holding pressure resulting in overheating.
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Thursday, December 12th, 2013 AT 7:26 PM
Tiny
JMANGANIELLO
  • MEMBER
  • 3 POSTS
I definitely boils over. I thought it might be the cap too, especially because the reservoir tank area is where it seems to lose the coolant. The coolant looks like it runs from the reservoir tank, down the engine side of the wheel well and hits the ground just behind the passenger side front tire. The cap is plastic with a brass liner behind the gasket. This last time I really made sure it was on there tight, but it still overheated after about 30 minutes.
I checked my oil level just to make sure it wasn't that, and noticed a grayish gummy mucous like residue on the bottom of the stick about the size of BB. I've never seen that before and don't know if it's even related.
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Thursday, December 12th, 2013 AT 8:02 PM
Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,005 POSTS
. And this is a 3.4l?

Mr. Radiator could be stopped up. Have it professionally cleaned or replaced it. It has a few years on it.$$$'s spent on cleaning it. Still leaves you with the same ole radiator

is your cooling fan coming on. Motor/ relay/ jammed?

I just looked up a water pump for a 3.4l. It has the same characteristics as these. This too, could be a possibility!

Click on each of my pics

1) plastic impellers. Gotta love 'em!

2) ford taurus

3) ford taurus (same one as above). Missing a piece. Magic. Where could it have gone?

Let us know what's going on. More questions. We're usually back on within 24 hours

the medic
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Thursday, December 12th, 2013 AT 8:08 PM
Tiny
TY ANDERSON
  • MECHANIC
  • 719 POSTS
If the engine oil is not looking like engine oil and more milky in color then there is oil/coolant mixing.
It is a possibility the water pump impeler(s) is damaged causing low coolant flow when the demand is needed such as at higher engine speeds but is difficult to tell without removing the water pump. These water pumps can come in plastic or metal impellers as mention above.
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Thursday, December 12th, 2013 AT 8:33 PM
Tiny
JMANGANIELLO
  • MEMBER
  • 3 POSTS
Ty;
The oil looks like oil, that gooey glob was on the bottom of the stick. The oil didn't appear milky, just that glob. Do you think I should pull the pump to check the impellers? What about the radiator. CJ suggested it could be clogged. How do you check that?
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Thursday, December 12th, 2013 AT 8:54 PM
Tiny
KERRI DEANESSA WHITLOW
  • MEMBER
  • 1 POST
I know that this is an old post but my car has exact issue. Did you ever find the issue? If so please tell.
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Monday, July 15th, 2019 AT 4:10 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,363 POSTS
Can you tell me if you hear the fan running when it is over heating? This guide can help us.

https://www.2carpros.com/articles/engine-overheating-or-running-hot

Please run down this guide and report back.
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Thursday, July 18th, 2019 AT 9:43 AM

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