Heating/cooling system

ANTTT6

MEMBER
2000 CHEVROLET 1500
5.3L
V8
4WD
AUTOMATIC
264,000 MILES

So I bought this truck from an older gentleman about 4 months ago. Truck has ran great since the purchase. Other than running hot while idle for 15+ minutes. Maintenance I’ve done since noticing the problem are as followed:

Fan clutch - 3 months ago
Water pump ( was leaking ) - 3 months ago
Thermostat - 3 months ago
Full coolant flush - 3 months ago

Still continued to run hot after idling 15+ mins

Valve cover gaskets - 2 months ago
Intake manifold gaskets - 2 months ago

A couple days ago I noticed I was losing coolant pretty quickly and found a hose had 2 pin holes. Replaced the bad hose and figured I’d do another coolant flush since I wasn’t getting any heat from the vents and one of the heater hoses wasn’t heating up.

So I done another full coolant flush. After the coolant flush I decided to forward & reverse flush the radiator and heater core by their selves. Heater core was full of rust. Now that the whole system is rushing clear distilled water throughout. I filled the system with the appropriate antifreeze and water. Let the truck run idle for 30 minutes. No over heat.

Well today, I’m sitting in a customers driveway doing paper work. After roughly 20 minutes I noticed my temperature was at about 220. I decided to sit and see what it would raise to and after about another 10 mins it got to roughly 230-235 degrees.

Any suggestions or ideas on why I am still running hot?

5 Replies

JACOBANDNICKOLAS

MECHANIC
109,913 POSTS

Welcome to 2CarPros.

It sounds like you have done it all. I will say, if you are sitting that long with the AC running in hot conditions, it will run hotter. When you say 220, that isn't so bad, but 230 or 235 is starting to push it.

At that temp, the fan should have been fully engaged. Did you notice any noise from it when you started driving that would indicate it was fully engaged and working properly?

Have you had the check engine light turn on when the engine is running? This is a reach, but things such as a rich or lean fuel mixture, ignition timing, and so on can cause an engine to run hotter. However, most times the things that lead to those conditions will set the check engine light. That's why I mentioned the light.

Let me know.

Joe

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Wednesday, August 21st, 2019 AT 6:29 PM

ANTTT6

MEMBER
3 POSTS

Fan, no. I have no notice it change at all. It is spinning from the time I crank the truck until the time I turn it off. I cannot tell if the speed is changing at all. I will monitor it tomorrow and see if there is any change.

Also, I do not have electric fans. The new fan clutch, if I’m not mistaken, was a severe duty fan clutch. Don’t know if that would matter.

Check engine light, it doesn’t illuminate. I do have an OBDll that can stay plugged in and I can monitor it on my phone. ($20.00 on Amazon) I’ll plug it in first thing in the morning and take a few screenshots and add them. Like I said, I’m no expert mechanic. I know enough to get me out of a serious bind.

Thank you for the reply.

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Wednesday, August 21st, 2019 AT 8:28 PM

JACOBANDNICKOLAS

MECHANIC
109,913 POSTS

Welcome back:

Most times, you won't hear the fan turning when the engine is cool or cold but it will be. However, as under hood temps increase, the clutch engages more and more, spinning the fan faster. When they are fully engaged, most times it sounds like a jet engine when the engine revs. See if you notice anything.

Let me know.

Take care,
Joe

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Wednesday, August 21st, 2019 AT 8:32 PM

ANTTT6

MEMBER
3 POSTS

So, first off, I apologize it took so long to reply. I’ve been really busy at work.

I’ve noticed that the fan clutch is working. After sitting idle for 20 minutes and then driving off it sounds like an airplane under the hood. So that’s good I guess.

The only thing I can logically think would be a culprit to the truck still over heating after idling would be the spaces in the radiator being dirty. Washed my truck yesterday and spray a little high pressure water through the radiator and nothing but black water drained from it. So instead of spreading $200.00 on a new one right off I am going to pull the existing one and and clean it thoroughly and see if that helps. Fingers crossed.

Also, attaching a video of my truck at an idle at lunch yesterday.

Video (Click to make bigger)