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2002 gmc envoy_slt
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Discussion Starter · #1 ·
I am having a problem with my 2002 Gmc envoy SLT 4x4. The truck leaked all the coolant out of the radiator and the tank last week. So not thinking much of it I refilled it with more dex cool and went on with it. Fast forward to today and bone dry again. I have found that the coolant is leaking underneath the truck and on to the driveway. I can't pin point the exact location of where the leak is coming from. I took the cover for the oil filter down and you can see the coolant dripping down but no exact location of where its coming from. To me its looking like the coolant is getting thrown around the underside of the car.

The truck does have 115k miles on it and I did replace the fan clutch at 50k with a updated GM fan. I'm leaning towards a water pump at the moment but still uncertain. I do know that none of the hoses are leaking.

FYI when driving the temp is fine but when you come to a stop and idle for a few minutes the temp goes up. The temp does go back down as you start to drive again.

Any help would be appreciated!!!
 

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2004 gmc
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I'm sorry, but I just have to ask what made you think a leak would magically repair itself when you threw in new fluid? That's stuff's not free, and neither is an engine!

A water pump is probably the cheapest place it could be leaking. Just run it and look very closely. Any wobble in its shaft if you wiggle the fan?

Assuming you got the new GM fan clutch design, then the radiator's should be cooled well in traffic, but idle problems are most likely the fan clutch. Can you see if trying to spin fast when you're overheating? It could easily have failed again if it was one of the early 2005 redesigns. GM goofed and had to redesign it AGAIN later in 2005.
 

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2006 chevy trailblazer_ls
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374 Posts
Phil's standard guide to locating leaks:

1) Clean it off

2) Idle it for 30 min or longer depending on leak severity

3) Look for where the stuff is coming out.

rinse and repeat as necessary :tiphat
 

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2006 chevy trailblazer_lt
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179 Posts
I agree with the roadie, filling it up probably didnt do anything, did it all leak out again? If so, check the water pump, it should have been replaced with the clutch anyway. If not, is the radiator cracked? Also, I would check the hoses, and see if they are broken or swollen. Also, let us know is the SEL light it on.
 

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2002 gmc envoy_slt
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Discussion Starter · #5 ·
haha yea I should have known about the leak. No wobble in the fan I wiggled it up and down side to side nothing. It does squeak a little on start up my wife says but other than that nothing. I did however notice that it doesn't kick in to high speed mode when it goes over 210 not sure what the temp is supposed to be for it. I drove it today so when It went over 210 It didn't kick on high mode.

But let's say its the fan is why its overheating what about the leak on the coolant how would the fan play into that?

Also would a SES light set for a thermostat? I ran my predator scanner on the the truck no codes at all and did notice that the ECT was in line with the gauge on the dash. So no temp sensor
 

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2006 chevy trailblazer_ls
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You may have 2 problems... One, a leak in your coolant system somewhere (see my post above to locate) and two, something causing overheating (assuming your leak isn't causing it). Check your radiator cap... that could be causing it. Thermostat springs to mind as well. And of course, there's always the possibility of the water pump. I've listed those in order from cheapest to most expensive, so try checking them in that order.
 

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2009 chevy
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No wobble in the fan I wiggled it up and down side to side nothing.
How are you trying that wobble test?

The best (only, in my opinion) is to remove the fan belt. When the belt is on, there is too much tension to check the pump bearings.

I doubt if you have two problems, the overheating is probably caused by low fluid, and/or a trapped air bubble inside the block.
 

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2006 chevy trailblazer_lt
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If the thermostat is stuck then the SEL light would illuminate, run a scan to check the ECM for any trouble codes, that would give you your best answer. If the thermostat was stuck, then wouldnt the engine be stuck in high idle mode?? Just a thought, not sure if that is right though.
 

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2006 chevy trailblazer_ls
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How are you trying that wobble test?

The best (only, in my opinion) is to remove the fan belt. When the belt is on, there is too much tension to check the pump bearings.

I doubt if you have two problems, the overheating is probably caused by low fluid, and/or a trapped air bubble inside the block.
The only reason I suggest two problems is that I don't know of overheating causing coolant to literally leak out of the radiator, and I'd think he'd notice the steam :shrug:
 

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2006 chevy trailblazer_ls
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:iagree: Anyways, first fix the leak, then let us know if it's still overheating... the leak is priority #1.
 

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2003 chevy trailblazer_ls
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I would get it checked ASAP. My dad had a similar incident about a month ago. We noticed that the temp. gauge was extreme. Coolant was low, added, low then added again, couldnt find a leak anywhere. Then one day coolant was all over the driveway. Told my dad to take it in to the shop. Took it in the engine block was cracked.

1997 chev. lumina ls

bought Sept 2005 paid 2700

scrapped June 30, 2009.
 

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2006 chevy trailblazer_ls
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374 Posts
I would get it checked ASAP. My dad had a similar incident about a month ago. We noticed that the temp. gauge was extreme. Coolant was low, added, low then added again, couldnt find a leak anywhere. Then one day coolant was all over the driveway. Told my dad to take it in to the shop. Took it in the engine block was cracked.

1997 chev. lumina ls

bought Sept 2005 paid 2700

scrapped June 30, 2009.
Good point. In your dad's case, all the overheating and cooling probably weakened the block to the point that it cracked. An expensive lesson learned.
 
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