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Discussion Starter #1 (Edited)
Hey Guys,


So, I noticed yesterday that my truck was leaking coolant. I rented a pressure tester and sure enough the rad sprung a leak. So, I went to auto zone and picked up a new radiator. Pulled out the old one and installed the new one. Filled it up. Attempted to burp the system and I thought I was all good to go.

Wrong.


She's not cooling at all now. Prior to me replacing the radiator everything worked fine. She didn't get hot. She ran at ~192 all the time. Everything was dandy.

Now, when i start the truck it warms up really quickly. If I leave it in park with the hood open and have the heat on full the temp will sit around ~210. If I turn the heat off it spikes to 225. If I try to drive it with the heat on the temp will rise. I shut her off at 230 because I don't want to hurt anything. The upper hose has pressure and is hot. The lower hose has pressure and is cooler. I have no idea what's going on. I tried burping the system again by parking the truck on an elevation, and with the cap off letting it run. The coolant level doesn't really seem to change. I don't see any bubbles. I tried squeezing the tubes, but coolant surges with no evident air coming out. When I turn the heat off while the truck is running with the cap off of the rad the coolant level rises and spills out of the radiator spout.

**Edit**

1. I've got an UltraGauge so I can tell what temp my coolant is at. I'm not guessing.

2. When the radiator cap is off, no matter what the temp, the coolant doesn't appear to move at all. It doesn't appear to me that there is any circulation. I'm starting to think it's the thermostat stuck closed or partially closed.


Thoughts?
 

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Has your water pump ever been replaced?
 

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Discussion Starter #3
Has your water pump ever been replaced?


No sir. Everything was working fine prior to the radiator install though. With the radiator cap off, if I revved the engine to 1000-1200 rpms coolant would spill out of the radiator spout. I should probably add I have the 3.7 with 62,XXX miles.
 

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If the radiator will eventually overflow, then it's likely the thermostat is not opening, or the pump isn't moving water quickly enough.

Water expands when it gets hot, so overflowing is possibly the result of a small amount of coolant going through the bypass or minimally open thermostat and back to the radiator. Normal operation would have the fluid raise to the top of neck a little before the thermostat opens, then it will rapidly lower with the opening of the thermostat. That's when I top off the radiator and put the cap back on.
That's how I used to do it, the last time I did a cooling system flush/fill (never on this engine).

I am not sure where the temperature sender is located, so it's hard to say where the coolant is reading as hot (unless you know).

How tight is your be;t...tight enough to spin the water pump? Tight enough to spin up the fan?

As a final thought, did you damage either of the hoses during disassembly/reassembly. If it's damaged (like it got driven over), maybe it's collapsing and causing restricted flow.

EDIT:
Was there any type of plug in the radiator spouts, like something to keep the neck from damage, that should have been removed. Perhaps the radiator itself has restrictions at the neck from some shipping component. If you find yourself removing the radiator, check it to make sure it's flowing properly (if you can determine what is proper).....to ensure the new radiator isn't clogged internally.
 

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When I installed my efan with inline temp sensor, I had to squeeze the hell out of the hoses to get it to burp. Took multiple sessions before success.


Sent from AutoGuide.com App
 

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I agree with FixxxerKH202 sounds like the themostat. Very rarely does a water pump fail because it is not moving the coolant unless it has a broken shaft or the impeller fell off. If that happen you would hear it. Though it was working before you replaced the radiatir it sounds like it is your thermostat. Like others have said replace it first.
 

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Discussion Starter #9 (Edited)
Well, I took a journey to the auto parts store this morning. Picked up a thermostat and replaced it. I checked the old one in boiling water and it did open, but only partially. Part of it seemed to stick. I also checked the new thermostat and it opened fine.


The problem has gotten better, but is not fixed. I can idle the truck with the rad cap on WITH HEAT ON, and it will sit around ~190. As soon as you turn the heat off, it jumps. When I go to drive it, no matter what you do with the heat, the temp climbs.


I'm lost. Im still wondering if theres a giant air bubble in the system, but I've been letting it run with the cap off through multiple thermostat open/close cycles and I'm not seeing anything.
 

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Gotta be a flow issue then........Thermostat eliminated means water is able to flow from radiator to block.

The radiator may be damaged or clogged. Or a restriction at the neck(s). Or a bad hose.

You didn't reply to earlier...is the belt tight?
 

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Discussion Starter #11 (Edited)
Gotta be a flow issue then........Thermostat eliminated means water is able to flow from radiator to block.

The radiator may be damaged or clogged. Or a restriction at the neck(s). Or a bad hose.

You didn't reply to earlier...is the belt tight?

Whoops, I never pressed submit.

The belt is tight and in good condition. The fan clutch is good. When I was replacing the rad and checked the hoses they appeared okay.
 

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Have you had it on the highway, or you can't get that far before the temp gets too high.

Wondering, because it should not need a fan to keep cool on highway (unless it's HOT where you are)-but IL doesn't seem to be hot right now. The air passing through the radiator should keep it cool.

Did you flush the system, or just drain fill? Wondering if you created a clog during the flush.

Can you verify the temp from Ultragauge is accurate? The dash gauge also reflects an increase in heat, similar to the digital reading? Although they could both indicate a change from previous, I'm just wondering if the sending unit coincidentally went wonky (technical term).
Can you get it to a shop to confirm temp? They may have an infrared thermometer.

There was a comment above too about the cap. Is it sludged up?
Seems you have left it run for a long enough time with the cap on as well.....the cap pressurizes the system. Water under pressure has an increased boiling temp. Should not affect temp I guess, but perhaps the water is too hot because of that?
Annnnnd, it's mixed adequately too -not mostly straight water?
 

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Discussion Starter #15
Have you had it on the highway, or you can't get that far before the temp gets too high.

Wondering, because it should not need a fan to keep cool on highway (unless it's HOT where you are)-but IL doesn't seem to be hot right now. The air passing through the radiator should keep it cool.

Did you flush the system, or just drain fill? Wondering if you created a clog during the flush.

Can you verify the temp from Ultragauge is accurate? The dash gauge also reflects an increase in heat, similar to the digital reading? Although they could both indicate a change from previous, I'm just wondering if the sending unit coincidentally went wonky (technical term).
Can you get it to a shop to confirm temp? They may have an infrared thermometer.

There was a comment above too about the cap. Is it sludged up?
Seems you have left it run for a long enough time with the cap on as well.....the cap pressurizes the system. Water under pressure has an increased boiling temp. Should not affect temp I guess, but perhaps the water is too hot because of that?
Annnnnd, it's mixed adequately too -not mostly straight water?


I can't get it to the highway to test. It's literally at 225 within minutes of driving off.

I did a drain and fill. I did not flush it. I'm working with very limited tools, supplies, and money. I'm currently down at school so all my normal tools are at home. I don't have a hose at my apartment so I couldn't flush the radiator.

The UltraGuage and dash gauge both correlate with each other.

The cap isn't sludged up. There actually wasn't any sludge at all in the system what I saw. The coolant was clean and clear.

It is a 50/50 mix.


As much as I love to work on vehicles, unfortunately this is my daily driver and being in college I NEED this truck operational. I'm sucking up my pride and taking it to a shop first thing tomorrow morning. I will keep y'all posted.
 

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Well, nothing should have gotten clogged during your work then. I was thinking something got dislodged and found it's way to a passage.

Kinda sucks. But it sure acts as if there is a flow restriction.
I'd suggest finding a shop that specializes in radiators/cooling systems as opposed to a general shop. Better experience in that aspect instead of a general mechanic.

Good luck - we're staying tuned.
 

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Discussion Starter #17
I really appreciate all the help guys. There are a lot of good people on this site :cheers:
 
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Double check your new radiator, if it is not clogged. Is it an oem replacement one? Same cooling capacity?
 

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Discussion Starter #20
SHE LIVES!

Alright, so I took her in to the shop as soon as they opened this morning. The guy got it in right away. Long story short it was the pump. It's weird because it wasn't making any noise and was working fine literally the day before. Oh well, weirder shit has happened i guess.

One thing I noticed is that the truck used to sit at 192 and now sits at 202-210. I'm guessing the old thermostat was a 180 and the new one is a 195. Other than that the temp is solid. Drove it around for awhile and no issues at all. I can go to work tomorrow!!
 
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